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Cognitive Psychology (PSYC 2650) Chapter Summaries

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PSYC 2650
Anneke Olthof

Cognitive Psychology Chapter  Summaries Chapter 1: The Science of the Mind The Scope of Cognitive Psychology • Cognitive psychology: the scientific study of the acquisitions, retentions and use of knowledge History • Cognitive psychology is roughly 50 years old • “Cognitive revolution” (1950-1960s) represented a striking change in the style of research and theorizing employed by most psychologists o It changed the intellectual map of the field The Years of Introspection th • In the late 19 century, scholars, Wilhelm Wundt and Edward Bradford Titchener launched research psychology, which defined it for the first time as separate from biology or philosophy o According to these men, psychology needed to be concerned largely with the study of conscious mental events—our feelings, thoughts, perceptions, and recollections • The only way to study thoughts is for each of us to introspect: ‘look within’to observe and record the content of our mental lives and the sequence of our own experiences • Introspectors had to be trained o They were given a vocabulary to describe what they observed o Trained to be careful and complete as possible o Trained to simply report on their experiences objectively • Concerns/Problems with introspection: o Some thoughts are unconscious, and this meant that introspection was limited as a research tool o We have no way of separating correct assertions from false ones o It became a matter of opinion, not objective facts o The testability of claims are unattainable • For science we need objective observations that we can count on The Years of Behaviourism • The concerns just raised led many psychologists (especially in the US) to abandon introspection as a research method • Data concerned with behaviour, stimuli and learning are objective o They are measurable, recordable and physical events • In contrast, beliefs, goals, expectations cannot be directly observed and therefore cannot be objectively recorded o These ‘mentalistic’notions were discarded o Scientific psychology needed to avoid these invisible internal processes/events • Behaviourist movement: a movement that dominated psychology inAmerica for the first half of the 20 century o It includes a range of broad principles concerned with how behaviour changes in response to different configurations of stimuli • Bu the late 1950s, psychologists realized that a great deal of our behaviour could not be explained only with reference to objective, overt events o The way people act is also guided by how they understand or interpret the situation o We must consider internal processes/events to understand behaviour • If scientists want to predict people’s behaviour, they need to refer to the stimulus and the person’s knowledge and understanding of and contribution to this stimulus o Stimuli that are physically different form each other have similar effects  Such as “Salt, please” o Stimuli that are physically similar to each other, have different effects  Such as “Pass the salt” and “Sass the palt” o Various stimuli evoke salt-passing do have something in common with each other: they all mean the same thing The Roots of the Cognitive Revolution • The solution to how we study the mental world was suggested by the philosopher Immanuel Kant o Transcendental model: begin with the observable facts and then work backwards from these observations  How could these observations have come about  What must the underlying causes be that led to these effects  Sometimes called “Inference to best explanation • To study mental processes, we must study them indirectly o Mental processes are invisible, but they have visible consequences, such as measurable delays in producing a response, performance that can be assessed for accuracy etc. • By examining these and other effects produced by mental processes, we can develop and test hypotheses about what the mental processes must have been Research in Cognitive Psychology: An Example • Kantian logic o Beginning with a particular performance, we then hypothesize a series of unseen mental events that made the performance possible o We ask whether some other sequence of events might explain the data, or whether some other sequence might explain both these data o We do more than ask how the data came about: we are also seeking the best way to think about the data • The hypothesise is tested by collecting more data o We seek to derive new predictions based on our hypothesis o If these predictions are confirmed, this is a strong argument that the proposed hypothesis is correct o If they are not, then a new hypothesis is needed Working Memory: Some Initial Observations • Working memory: the memory you use for information that you are actively working on o It holds information in an easily accessible form, so that the information is instantly available when needed • Working memory is hypothesized to have only a small capacity o With only a few items in this store, there will never be a problem locating the item you want • Measuring working memory’s capacity via a span test o The participant reads a list of 4 items and reports these back, immediately, in sequence, for instance letters o If they succeed, another letter is added to the list and this continues until the person can no longer report back accurately o People start making errors with sequences of 7-8 letters Working Memory: A Proposal • When measuring people’s memory span, we find that they often make errors, in particular by reporting letters that they hadn’t heard at all o They tend to substitute one letter for another with a similar sound o We get similar sound-like confusions if the letters are presented visually • Baddeley and Hitch proposed a model: o They assumed that working memory is not an entity, but instead it has several components known as the working-memory system o At the heart of the system is the central executive: this part runs the show and does the real work  The executive interprets and analyses information, which the assistants can’t do • Central executive assistants o Is helped out by a number of low-level ‘assistants’, which aren’t sophisticated but useful for temporary storage of information o One is the articulatory rehearsal loop: repeating information and rehearsing them with your inner voice, which requires little effort  The executive has initiated the speech, but the chore to hold the information is passed on to the assistants, freeing the executive • Sub-vocalization produces a representation of the items (such as numbers) in the phonological buffer: an auditory image is created in the ‘inner ear’ o This image will fade away after a second or two, but before it does, the executive ‘reads’the contents of the buffer, in order to remind itself what the numbers were o Then it initiates the next pronunciation by the inner voice and begins another cycle and goes back to other business o The executive is needed once per cycle: to launch the next round of sub- vocalization Evidence of the Working Memory System • Why people make ‘sound-alike’errors in a span task o They’re relying on the rehearsal loop, which involves the ‘inner voice’that is used for overt speech and the ‘inner ear’, which us used for actual hearing o The memory items are briefly stored as internal representations of sounds, and therefore when errors occur they are shaped by this mode of storage • Concurrent articulation task: asking people to take the span test while simultaneously saying “Tah-Tah-Tah” over and over, out loud o This task requires the mechanisms for speech production, which makes them unavailable for other use, such as sub- vocalization o This is because, you can’t use muscles in 2 different ways at the same time, so you cannot sub-vocalize one sequence while overtly vocalizing something else How will the concurrent articulation constraint matter? • The original span test measured the combined capacities of the central executive and the loop o However, with concurrent articulation, the loop isn’t available for use, so we are measuring the capacity of the working memory without the rehearsal loop o Hypothesis: concurrent articulation cuts memory span short  This is true, the span is normally 7-8 items, with concurrent articulation, it drops to 3-4 items • With visually presented items, concurrent articulation should eliminate the sound-alike errors o With this task, we block the use of the loop, in which sound-alike errors arise • Testing people’s memory span of complex visual shapes which cannot be easily named, means they cannot be rehearsed via the inner-voice/-ear combination o This task does not use the rehearsal loop, therefore there should be no effect of concurrent articulation The Nature of the Working­Memory Evidence • We can gain further insights into working memory by considering the biological mechanisms that make this performance possible o Such as drawing evidence from the realm of cognitive neuroscience: the study of the biological basis of cognitive functioning • What exactly is the nature of sub-vocalization? o Does it literally involve covert speech and thus movements of the tongue and vocal cords? o This can be tested through specific forms of neurological damage, from individuals who suffer from anarthria, where they have no ability to move these various muscles and so are unable to speak o What does the research say about individuals who suffer from anarthria?  These individuals show sound-alive confusions in their data, like normal people o This suggests that actual muscle movements are not needed for sub-vocalization o The ‘inner speech’relies on the brain area responsible for planning the muscle movements of speech • Neuropsychology: concerned with how various forms of brain dysfunction influence observed performance Chapter 2: The Neural Basis for Cognition Capgras Syndrome: An Initial Example • Capgras syndrome: a rare disorder that can result from various injuries to the brain and can be one of the accompaniments toAlzheimer’s o Someone with this syndrome is fully able to recognize the people in their world but is utterly convinced that these people are not who they appear to be o They believe instead that these people are well-trained, well-disguised impostors o The patient may also develop all sorts of paranoid suspicions about why a loved one has been replaced and why no one seems to acknowledge this replacement • What is going on here? o Facial recognition involves 2 separate systems in the brain: 1) Cognitive appraisal: “I know what my father looks like, and you look similar to him” 2) Emotional appraisal: “You look familiar to me and also trigger a warm response in me” o Both of these appraisals, together leads to the certainty of recognition o However, in Capgras syndrome, the emotional appraisal processing is disrupted, leading to the intellectual identification without the familiarity response The Neural Basis for Capgras Syndrome • Neuroimaging techniques: allow researchers to take high-quality, 3-D ‘pictures’of living brains, without in any way disturbing the brain’s owners, which include: o Positron emission tomography (PET) scans o Functional magnetic resonance imaging (fMRI) scans • Neuroimaging scans suggest a link between Capgras syndrome and abnormalities in several brain areas, such as: o Amygdala: an almond shaped-structure that serves as an ‘emotional evaluator’, helping an organisms detect stimuli associated with threat/danger and safety/rewards  Damage to the temporal lobe on the right side of the head o Prefrontal cortex: in the frontal lobe • Important information about Capgras syndrome comes from fMRI scans of patients with schizophrenia: o When experiencing hallucinations there is diminished activity in the frontal lobe o This reflects a decreased ability to distinguish internal events (thoughts) from external ones (voices) or to from imagined events to real ones o Capgras patients may be less able to keep track of what is real and what is not, due to damage to the frontal lobe What do we learn from Capgras Syndrome? • In summary we have learned: o The damage to the amygdala is likely to be the reason why Capgras patients experience no sense of familiarity when they look at faces they know quite well o The damage to the prefrontal cortex, helps us understand why Capgras patients offer such crazy hypotheses about their skewed perception • Capgras syndrome tells us that this emotional evaluator works in a fashion separate from our evaluation of factual information The Principle Structures of the Brain Hindbrain, Midbrain, Forebrain • The human brain is divided into 3 main structures: o Hindbrain  Sits directly atop the spinal cord  Includes structures crucial for controlling key functions, such as heartbeat rhythm and breathing  It helps maintain the body’s posture and balance  It regulate the brain’s level of alertness  The largest area of the hindbrain is the cerebellum • It was believed its main role was in the coordination of our bodily movements and balance, however, it also includes: o Spatial reasoning o Discrimination of sounds o Integration of the input received from various sensory systems o Midbrain  Coordinates our movements, such as eye movement  Relays auditory information from the ears to the areas of the forebrain where this information is processed and interpreted  Regulates our experience of pain o Forebrain  Is the largest area  It surrounds the entire midbrain and most of the hindbrain  Cortex: is the thin outer surface of the forebrain, that is on average 3 mm thick • It constitutes 80% of the human brain • The cortex is all crumpled up which produces the brain’s wrinkles or convolutions • The valleys between the wrinkles are actually deep groves that anatomically divides the brain into different sections: o Longitudinal fissure: is the deepest grove, that runs from the front of the brain to the back and separates the left cerebral hemisphere from the right o Central fissure: divides the frontal lobes on each side of the brain from the parietal lobes o Lateral fissure: at the bottom edge of the frontal lobe and above the temporal lobe • Other fissures divide the cortex in each hemisphere into 4 lobes that are named after the bones that cover them: o Frontal lobes: form the front of the brain, right behind the forehead o Parietal lobes: the brain’s top-most part o Temporal lobes: under the lateral fissure o Occipital lobes: at the very back of the brain, connected to the parietal and temporal lobes Subcortical Structures • Underneath the cortex, are the subcortical parts of the forebrain: o Thalamus: acts as a relay station for nearly all the sensory information going to the cortex o Hypothalamus: under the thalamus, which plays a crucial role in the control of motivated behaviours, such as eating, drinking and sexual activity o Surrounding the thalamus and hypothalamus is another set of interconnected structures which form the limbic system:  Amygdala: emotional processing  Hippocampus: learning and memory, formation of new memories • Like most parts of the brain, the subcortical structures come in pairs, which means there is a left side and right side to every part o These pairs have roughly the same shape and position, but there are differences in the functioning of these parts • The two halves of the brain work together o The functioning of one side is closely integrated with that of the other side o This integration is made possible by the commissures:  Thick bundle of fibers that carry information back and forth between the 2 hemispheres  The largest being the corpus callosum Neuroimaging Techniques • The symptoms that result from brain damage depend heavily on the site of damage o Lesion: a specific area of damage o The consequences of brain lesions depend on which hemisphere is damaged as well • Neuroimaging allows us to take precise 3-D pictures of the brain, and several techniques are available including: o Computerized axial tomography (CT)  Used to study the brain’s structure  Use X-rays to study the brain’s anatomy  The results are relatively stable o Positron emission tomography (PET)  Used to study the brain’s function  Provides precise assessment of how blood is flowing through each region of the brain  It relies on the fact that when a particular brain area is more active it needs and receives a greater blood flow  The results are highly variable, depending on the task the person is performing o Magnetic resonance imaging (MRI)  Used to study the brain’s structure  Relies on the magnetic properties of the atoms that make up the brain tissue and yields detailed pictures of the brain  The results are relatively stable o Functional magnetic resonance imaging (fMRI)  Used to study the brain’s function  Measures the oxygen content in the blood flowing through each region of the brain  It provides a precise picture of the brain’s moment-to-moment activities  The results are highly variable, depending on the task the person is performing Neuroimaging: Study by Tong, Nakayama, Vaughan and Kanwisher (1998) • The study conditions: o Participants were looking at pictures of faces while their brain were scanned  This showed high activation in the fusiform face area (FFA): an area that is highly responsive to faces mainly o Participants were looking at pictures of houses while their brain were scanned  This showed high activation in the para-hippocampal place area (PPA): an area that responds actively to pictures of places o Apicture of a face was put in front of one of the participants eyes, while a picture of house was put in front of the other eye  Binocular rivalry: the visual system is unable to handle both stimuli at once, or fuse them into a single complex perception  Instead, the visual system seems to flip-flop between the stimuli, so that for a while the person is aware only of the face; then of the house • Binocular rivalry study o The participants pressed buttons to indicate, at each moment in time, whether they were aware of seeing the house or the face o AfMRI was used to track the activity levels of the FFAand the PPA o What do we expect?  If these brain areas respond to the stimuli that are available, then the activity levels would not vary as the experiment progressed  If these brain areas reflect the participant’s conscious perception, then activity should fluctuate, with a change in brain activity occurring each time • This statement is true Correlation versus Causation • Localization of function • Neuroimaging data tells us whether a brain area’s activity is correlated with a particular function, but we need other data to ask whether those brain sites play a role in causing that function • Trans-cranial magnetic stimulation (TMS) o This technique creates a series of strong magnetic pulses at a specific location on the scalp, causing temporary disruption on the small brain region directly underneath it o With this, we can find out what functions are compromised when particular brain tissue is ‘turned off’ o As a result, we can ask, in a normal brain, whether that brain tissue plays a casual role in supporting the appropriate brain function Primary Motor Projection Areas • Primary projection areas: are in a strip of tissue located toward the rear of the frontal lobe and includes: o Primary sensory projection areas: the arrival point for information coming from the eyes, ears and other sense organs o Primary motor projection areas: the departure point for signals leaving the forebrain and controlling muscle movement • Contralateral control: with stimulation of the left hemisphere leading to movements on the right side of the body • In this drawing, a person has been overlaid on a depiction of the brain, with each part of the little person positioned on top of the area of the brain that control its movements o Areas of the body that we can move with great precision (fingers, lips) have a lot of cortical area devoted to them o Areas of the body which we have less control (shoulder, back) receive less cortical coverage Primary Sensory Projection Areas • If a patient’s brain is stimulated in this region (with electrical current or touch) they report: o Somatosensory area (Parietal lobe): tingling sensation in a specific part of the body o Auditory area (Temporal lobe): hear clicks, buzzes and hums o Vision area (Occipital lobe): produces the experience of seeing flashes of light or visual patterns • These sensory projection areas have features in common and parallel the attributes of the motor projection area 1) They provide a map of the sensory environment 2) In each of these maps the assignment of cortical space is governed by function, not by anatomical proportions 3) There is evidence of contralateral connections Association Areas • Both projection areas make up only a small part of the human cortex—roughly 25% o The remaining cortical area are traditionally referred to as the association cortex: this section performs the task of associating simple ideas and sensations in order to form more complex thoughts and behaviours • Brain tissue can be subdivided further on both function and anatomical grounds o This is best revealed by the diversity of symptoms that result if the cortex is damaged in one or another specific location  Frontal lobe lesions • Apraxia: disturbances in the initiation/organization of voluntary action • Left frontal lobe lesions o Aphasia: disruption to language capacities • Prefrontal lobe lesions o Problems in planning and implementing strategies o Problems in inhibiting behaviour o Relying on habit, even in situations where it’s inappropriate o Leads to a variety of confusions  Occipital lobe lesions • Agnosias: disruptions in a person’s ability to identify familiar objects  Parietal lobe lesions • Neglect syndrome: the individual seems to ignore half of the visual world • In summary, these various clinical patterns make it clear that the so-called association cortex contains many sub-regions, each specialized for a particular function, but with all of them working together in virtually all aspects of our daily lives The Visual System The Photoreceptors • The sequence of vision: 1) Light is reflected off objects in our surroundings 2) Some of this light hits the front surface of the eyeball, passes through the cornea and the lens  These focus the incoming light, so that a sharp image is cast onto the retina  The cornea is fixed in shape, but the shape of the lens can be adjusted by a band of muscle that surrounds it • Tightening muscles and fatter lens focuses close objects • Relaxed muscles and thinner lens focuses farther objects 3) The light then hits the retina is the light-sensitive tissue that lines the back of the eyeball  The center of the retina is the fovea, which perceives the greatest acuity and has only cones • The retina has 2 types of photoreceptors: cells that respond directly to the incoming light: 1) Rods: are sensitive to much lower levels of light and function as night-vision  They are colour-blind  They distinguish among different intensities/brightness of light, but cannot discriminate between hues  Dominates the visual periphery 2) Cones: are less sensitive than rods and need more incoming light to operate at all  Are sensitive to colour differences  There are 3 types of cones, each having its own pattern of sensitivities of different wavelengths  They allow us to see in detail, known as acuity  Dominates in the fovea, the center of vision Lateral Inhibition • The photoreceptors stimulate bipolar cells, which in turn excite ganglion cells o Ganglion cells: collect information from all over the retina and then gather together to form the bundle of nerve fibres called the optic nerve o Optic nerve: leaves the eyeball and carries information to various sites in the brain, such as the LGN o Lateral geniculate nucleus (LGN): information is transmitted to the primary projection area for vision in the occipital lobe • Lateral inhibition: a pattern in which cells, when stimulated inhibit the activity of neighbouring cells Chapter 3: Recognizing Objects • Focus: fundamental problem of how you manage to recognize the objects you encounter every day Form Perception: • We have various sensory modalities (sight, smell, touch) • Vision is the dominant sense – we more brain area devoted to vision compared to other senses • If visual information conflicts with information from other senses, we usually place our trust in vision o For example ventriloquism • Form perception: the process through which you manage to see the basic shape and size of an object o The processes that tell us the shapes, sizes, and positions of the objects in front of our eyes • Object recognition: the process through which you identify what the object is Why is Object recognition so Crucial: • All use of knowledge depends on form perception and object recognition • You know perfectly well how to use a telephone, or how to open a door, or what a chair is for, but you’d never be able to use this knowledge if you couldn’t recognize these objects when you saw them • Object recognition is essential whenever you want to apply your knowledge to the world • Without recognition, there will be no way for you to combine information bits collected on different occasions • Recognition is essential for our interactions with the world Beyond the Information given • Gestalt psychologist noted that our perception of the visual world is organized in ways that the stimulus input is not o They argued that the organization must be contributed by the perceiver o This is why they claimed the perceptual whole is often different from the sum of its parts o Jerome Bruner (1973): “beyond the information given” describing some of the ways that our perception of a stimulus differs from (and goes beyond) the stimulus itself Necker Cube: • Is an ambiguous figure, because there is more than one way to perceive it o It is a reversible figure: since people perceive it first one way, and then another • Both perceptions fit perfectly well with the information received by our eyes, and so the drawing itself is fully compatible with either of these perceptions • Your perception is NOT neutral; you perceive the cube as having one configuration or another Ambiguous figures: (vase / faces) • Figure/ground organization: the determination of what is o The figure—object against background, and what is o The ground—the background • Perception contains information – how the form is arranged in depth, or about which part of the form is figure and which is ground o This is contributed by the perceiver (you) The Gestalt Principles: • With reversible figures your perception goes back and forth • However, the information that’s actually reaching your eyes is constant – the exact geometry of the figure is the same, no matter how you perceive it • The change is caused by YOU – change in how you’re organizing and interpreting the stimulus (and thus your role in shaping the perception is perfectly clear) • Many stimuli (and not just reversible figures) are ambiguous and in need of interpretation • We don’t often detect the ambiguity, because we interpret it so quickly • Fruit bowl: the stimulus doesn’t guarantee the banana shape or the continuity of the stripes, these points are just your interpretation • Our interpretation of stimuli is guided by a few straightforward principles (catalogued by gestalt psychologists) – essential if your perception apparatus is going to make sense of the often ambiguous, often incomplete information provided by your senses o Everyone’s perceptions are guided by the same principles – which is why you generally perceive the world the same as other people do Principles • The Gestalt principles include: 1) Similarity: tend to group dots into columns rather than rows, grouping dots of similar colours 2) Proximity: we tend to perceive groups, linking dots that are close together 3) Good continuation: tend to see a continuous green bar rather than two smaller rectangles 4) Closure: tend to perceive an intact triangle, reflecting our bias toward perceiving closed figures rather than incomplete ones 5) Simplicity: tend to interpret a form in the simplest way possible. Would see two intersecting rectangles rather than a single 12 sided irregular polygon • We all tend to impose the same interpretation, because we’re all governed by the same rules Organization and Features • Perception proceeds in two broad steps: 1) We collect information about the stimulus, so that we know what corners or angle or curves are contained in the input 2) Once we gathered the raw data, we interpret this information -and we “go beyond the information given” – deciding how the form is laid out in depth (what is figure, what is depth, etc.) • Our interpretation sometimes happens before we start cataloguing the inputs basic features, NOT after (i.e. discovering the word hidden in the figure) • With one organization, the features are absent; with another, they’re plainly present • The features themselves depend on how the form is organized by the viewer – so the features are as much “in the eye of the beholder” • Many aspects of the brains functioning depend on parallel processing, with different brain areas all doing their work at the same time • Different brain areas all influence each other - one brain region is shaped by what’s going on elsewhere – neither type of processing goes first! o Neither has priority; they work together making sure the achieved perception makes sense Object Recognition: • We’re also able to identify objects we encounter – to recognize a shape as a truck, tree, and character in a video game Recognition: Some early considerations • We can recognize a huge number of patterns – objects (cats, cups), actions (running, jumping), and situations (crisis, comedy) • We can recognize variations – cat standing up, sitting down • We can recognize objects even when your information is partial (i.e. only seeing a cat’s head or foot); also can recognize words whether printed large, small, in italics, etc. • Bottom up influences: influences that come directly from the stimulus itself – the features that are in view aka stimulus driven • Top down influences: influences that rely on your knowledge (knowledge driven / expectation driven); cases that go “beyond the information given” Features: • Many objects are recognized by virtue of their parts (elephants trunk) • How do you recognize the parts themselves? • Recognition might begin with the identification of visual features in the input pattern (vertical lines, curves, diagonals) o With these features appropriately catalogued, you could then start assembling larger units • Specialized cells in the visual system that seem to act as “feature detectors” providing the exact right start for the ideas we are now considering • Integrative agnosia: damage to the parietal cortex o Appear relatively normal in tasks requiring them simply to detect particular features in a display o Impaired in tasks that require them to judge how the features are bound together to form complex objects o Shown from studies of brain damage o Similar results shown in TMS (trans-cranial magnetic stimulation) Word Recognition: • Object recognition begins with detection of simple features • Separate mechanisms are then needed to put the features together to form complete objects Factors influencing recognition • Tachistoscope: device specifically designed to present stimuli for precisely controlled amounts of time • Each stimuli is followed by a post stimulus mask – often a random jumble of letters (XJDKEL) which serves to interrupt any continued processing that participants might try to do for the stimulus just presented • People recognizing the briefly visible stimulus depends on how familiar a stimulus is (i.e. words) and recency of view (will recognize it much more readily the second time) o First exposure primes the participant for the second exposure = repetition priming The Word­Superiority Effect • Frequently viewed words and recently viewed words are easier to perceive • Words are easier to perceive more than single letters = word superiority effect • Accuracy rates are higher in the word condition (vs isolated letters) as shown in “two alternative, forced choice” procedure • We are more accurate in identifying letters if those letters appear in a word than recognizing isolated letter Degrees of Well­Formedness • There is no context effect if a string like “HZYE” is presented – E presented in these strings will not show the word superiority effect, but will in a word like “FIKE” o Although it is not a real word, it looks like a real word, and are easy to pronounce • Pronounce-ability = easily pronounceable strings (FIKE/LAFE) provides a context benefit • Not readily pronounceable words (HZYE) has little/no context benefit • Statistical measure of probability (how often letter combination FI, FIK, etc. occurs) – the strings evaluate the “Englishness” of any letter string Making Errors • We have an easier time recognizing sequences that use common letter combinations • There is a strong tendency to misread less common letter sequences as if they had more common patterns – irregular patterns are misread as if they were regular patterns but the reverse error is rare • Misspelled words, partial words, or non-words are read in a ways that brings them into line with normal spelling Feature Nets and Word Recognition • What lies beyond this broad pattern of evidence? The Design of a Feature Net • System that will recognize the word CLOCK • Idea of a network of detectors organized in layers – with each layer concerned with more complex , larger scale objects • Bottom layer concerned with features • Networks of this sort often referred to as feature nets and the term bottom up • Each detector in the network has a particular activation level (reflecting status of the detector at that moment) • The activation level will eventually reach the detectors response threshold – where the detector will send a signal to the other detectors to which it is connected • Some activators are easier to activate than others o Detectors that have fired recently will have a higher activation level (recency) o Detectors that have fired frequently in the past will have a higher activation level (frequency) o Therefore, frequent and recent words will have higher levels of activation • In terms of repetition priming: presenting a word once will cause relevant detectors to fire; once fired, activation levels will be temporarily lifted and only a weak signal will be needed the second time around The Feature Net and Well­Formed­ness • Well-formed words involve familiar letter combinations • HICE will only need a low activation point whereas HCIE will need a high activation level at the start • Bigram detector: o Word detector = clock o Bigram detector = CL, LO, CK o Letter detector = C, L, O, C, K o Feature detectors = the shapes Recovery from Confusion • With a brief presentation of a word, the visual system has limited opportunity to analyze the input – it’s possible for the visual system to miss some of the present features • The signal being sent from the letter detectors is roughly “maybe CO, maybe CU, maybe CQ or CS” if we only saw the “bottom curve detector” • The confusion is sorted out at the bigram level: all four bigram detectors are receiving the same input but CO and CU is a frequent pattern (more primed) so there will be more activation; CQ and CS is less frequent (less well primed) so it won’t respond to the weak input • In a totally automatic fashion, the network recovers from its own confusion and an error has been avoided Ambiguous Inputs THE CAT • The uncertainty is resolved at subsequent levels • Aand H will fire weakly – it will then be sent to the bigram level (TAand TH) and to the word level (THE and TAE) -> TH and THE is enormously primed, TAE is barely primed • Context allows you to make better use of what you see Recognition Errors • Downside to the context: CQRN that is presented only shortly will register as CORN since the other less primed detectors will not respond • The network is biased, inevitably favouring frequent letter combinations over infrequent ones • The network operates on the basis of “when in doubt, assume the input falls into the frequent pattern” – since frequent patterns are well primed and easier to trigger • This bias can turn irregular spelling into more frequent combinations Distributed Knowledge • The networks functioning is guided by knowledge of spelling patterns • The network knows CO is a common bigram in English, and CF is not • The network seems to rely on this knowledge in choosing its interpretation of unclear or ambiguous inputs • The network seems to expect certain patterns and not others - and is more efficient when the input lines up with those expectations • Knowledge about spelling patterns is not explicitly stored somewhere, but instead certain detectors are just more PRIMED than others • Both detectors are just doing their job and there is sometimes a competition between the two that is resolved in a straightforward way by activation levels • The networks “knowledge” is not locally represented anywhere (not stored or built in a particular location) and therefore, we cannot look at a level of priming • Instead, we need to look at the relationship between their levels of priming • Knowledge of bigram frequencies is distributed knowledge – represented in a fashion that’s distributed across the network and detectable only if we consider how the entire network functions • The activity of each detector is locally determined – influence by just those detectors feeding into it – when all of the detectors work together, the process acts as if it knows the rules but the rules themselves play no role in guiding the networks activities Efficiency vs Accuracy • The network DOES make mistakes, misreading some inputs and misrepresenting some patterns – produced by the same mechanism that is an advantage – the ability to deal with ambiguous inputs • To maximize accuracy, you could scrutinize every character on the page – but this would make reading much slower • Instead, we read letters and make inferences about the rest • Inferential strategy (we don’t need every letter to identify what a word is due to the redundancy of the English language) Descendants of the Feature Net • Variations on the basic conceptualization: o Inhibitory connections among detectors o Applies the network idea to the recognition of complex three dimensional objects o Your ability to recognize objects may depend on your viewing perspective when you encounter those objects The McClelland and Rumelhart Model • Activation of one detector serves to activate other detectors • Some detectors inhibit others • An early model was proposed by McClelland and Rumelhart (1981) • Model includes both excitatory connections and inhibitory connections – better able to identify well-formed strings than irregular strings • Excitatory connections: activation of one detector causes activation of its neighbours • Inhibitory connections: detection of G inhibits the TRIP detector • Higher level detectors (word detectors) can influence the lower level detectors, and detectors at any level can also influence other detectors at the same level • Activation of TRIP will deactivate TRAP or TAKE • Two way communication – similar to the idea that visual processing is not a one way process • Designed initially as an account of how people recognize printed language Recognition by Components (RBC) (network theory 2) • Used to recognize 3D objects like cars, trees, lamps, etc. • Includes intermediate level of detectors, sensitive to geons (geometric icons) • Geons: serve as the basic building block of all the objects we recognize – the alphabet for which all objects are constructed o Geons are simple shapes (cylinders, cones, blocks) – only a few are needed o We need only three dozen geons to describe every object in the world (like 26 letters in the alphabet) o Geons can be combined in various ways - top of relation, side connected relation, etc. • Theory uses a hierarchy of detectors o Lowest level detectors: feature detectors that respond to edges, curves, verticals, etc., that activate the geon detectors o Higher levels of detectors: are sensitive to combinations of geons o Geons are assembled into more complex arrangements called geon assemblies o Assemblies activate the object model – representation of the complete, recognized object • Geons can be identified from virtually any angle of view • Recognition based on geons is viewpoint-independent (able to recognize a cat from the side) • Most objects can be recognized from just a few geons • Some evidence confirms that geons do play a role in recognition – recognition of simple objects is easy if geons are easy to discern; recognition is more difficult if geons are hard to identify Recognition via Multiple Views • Propose that people have stored in memory a number of different views of each object they can recognize (view of what a cat looks like head on) • The number of views in memory is limited (1/2 dozen or so) – will need to rotate the current view to bring it into alignment with one of the remembered views - rotation will cause a slight delay in recognition • Recognition sometimes requires mental rotation – will be slower from some viewpoints than from others = recognition will be viewpoint dependent • Hierarchy of detectors with each successive layer within the network concerned with more complex aspects of the whole o Low level detectors: respond to corners and notches o Top level detectors: respond to the sight of whole objects o Detectors fire when there is a match to one of these view turned representations • Many neurons seem object specific – fire when a certain object is on the scene • They fire most strongly to a particular view of the target objects • Controversy: o RBC = recognition is largely viewpoint independent o Multiple views approach = recognition is viewpoint dependent Different Objects, Different Recognition Systems? • Recognition of faces seems to demand a different approach Faces are special • Damage to the visual system can cause agnosia disorder – inability to recognize certain stimuli • Different subtypes of agnosia: o Prosopagnosia: lose ability to recognize faces even though other visual abilities seem to be intact o Face recognition is specialized in its strong dependence on orientation • The perception of faces is very different from other forms of perception – with place perception more strongly dependent on orientation (performance suffered for all the upside down stimuli) • Prosopagnosia can also affect car recognition, bird recognition, etc. • Fusiform face area (FFA) is specifically responsive to faces – distinction among birds and cars also show high levels of activation in this area • The system seems crucial whenever a task has two characteristics o The task has to involve recognizing specific individuals within a category o The category has to be extremely familiar Holistic Recognition • Networks we’ve been using focus on analysis of a patterns parts (feature, geons) • Face recognition doesn’t depend on an inventor of a faces parts – it depends on holistic perception of the face – recognition depends on complex relationships created by the faces overall configuration o Spacing of the eyes relative to the nose o Height of the forehead relative to the width of the face, etc. • Key: features can’t be considered one by one but they matter by virtue of the relationship and configuration they create • Evidence comes from the composite effect in face recognition- scientists combined top half of one face with bottom half of another face o When the two halves are aligned it is much harder to recognize the top half – have a difficult time focusing on just the top – instead they see it as a whole o Task is easier when halves are not aligned – the stimulus breaks up the configuration Top Down Influences on Object Recognition The benefits of larger contexts • Words are easier to recognize if you see them as a part of a sentence then they are if you see them in isolation • Participants more likely to recognize “CELERY” with a cue such as “the word is the name of something you can eat” = large priming affect • For this to happen the person must understand each of the words in the instructions and must understand the syntax of the instructions • Knowledge that is external to object recognition (knowledge about what is edible) is important and influences the process Chapter 4: Paying Attention Selective Listening • Shadowing task: participants hear a tape recording of someone speaking and must echo this speech back, word for word, while they are listening to it o It becomes relatively easy after a minute of practice, but is difficult at first • Dichotic listening: o Attended channel: the message to be shadowed is presented through stereo headphones, so that participants hear it through the right earphone (for instance) o Unattended channel: a different message is presented in the left earphone (for instance), and participants are instructed simply to ignore this message • Participants easily follow one message and their shadowing performance is generally near perfect o They hear relatively little from the unattended channel o They cannot report the unattended message or what it was about • There is a similar pattern with visual inputs o Participants were asked how many times did the ball switch hands on the white team only (ignoring the black team), while watching a video o Participants were so intent on this task that they missed other salient events that appeared on the screen • Are people really oblivious to the unattended channel? o No, people can accurately report whether the unattended channel contained human speech, musical instruments or silence o The physical attributes of the unattended channel were heard, but the semantic content was not Some Unattended Inputs are detected • Some bits of the unattended input seem to ‘leak’through and get noticed • In another experiment, embedded within the unattended channel was a series of names, including the participant’s own name o The name seemed to catch the participant’s attention o Other contents that will catch your attention, if you are suitably primed, include:  Mentioning a movie you just saw  Mentioning your favourite restaurant  Words with some personal importance • Cocktail party effect: o Many other conversations are taking place in the room, but somehow you are able to ‘tune them out’ o All you hear is the conversation you are attending to and background noise o However, if someone nearby mentions your name or of a close friends, your attention is immediately caught and you find yourself listening to that conversation now Perceiving and the Limits on Cognitive Capacity • We somehow block processing of the inputs (i.e. unattended input) we’re not interested in • We erect a filter that shields us from potential distractors o Desired information (the attended channel) is not filtered out and so goes on to receive further processing • We shut out distractors on a distractor-by-distractor basis o We can inhibit our response to this distractor and do the same for that distractor and be successful in doing so o However, the same efforts are of little value if some new distractor comes along  In this case, we need to develop a new skill aimed specifically at blocking this new distractor • We are able to promote the processing of desired stimuli In­attentional Blindness • Perception involves a considerable amount of activity—as you organize and interpret the incoming stimulus information o This activity would require some initiative and some resources • An experiment involves the participant’s ability to notice different lengths of crosses (+) in their peripheral vision while staring directly at a target (dot) o Eventually the target changes into a shape o The participants did not realise this happened • What is going on in this study? o Some researchers have proposed that the participants in this experiment did see the target shapes but couldn’t remember what they had seen o Mack and Rock note that participants were not expecting any shapes to appear and were not in any way prepared for these shapes  In-attentional blindness: The participants literally failed to see the shapes, even though they were staring straight at it Conscious Perception, Unconscious Perception • Mark and Rock claim that there is no conscious perception without attention • In another experiment, participants were shown a series of images, each containing a pair of horizontal lines o Their task was to decide which was the two lines was longer o For the first 3 trials, the background dots were arranged randomly (seeA) o For the 4 trial, the dots were arranged reproducing the Muller-Lyer illusion (see B) • The participants were influenced by the dot pattern o In the Muller-Lyer illusion, fins make the top horizontal line appear longer than the bottom one o They are both the same length o 95% of the participants reported that the top line was longer • The participants, also, were completely unaware of the fins, but were still influenced by them o Conclusion: the participants did perceive the fins but did not consciously perceive them • Perhaps you can unconsciously detect and be influenced by patterns in the world even in the absence of attention Change Blindness • Change blindness: observer’s inability to detect changes in scenes they are looking directly at • In some experiments, participants are shown pictures separated by a brief blank interval o The pictures shown are identical, expect for one aspect o Participants know from the start that their task is to detect changes, but this is difficult • There are differences in how long it takes the participants to find the change and where the change is in the scene o If the change is something central to the scene, observers may need as many as a dozen alternations between the pictures o If, however, the change is something peripheral to the scene, observers may take as many as 25 alternations! Early Versus Late Selection • There are 2 ways we might think about the above experiment: 1) These studies show genuine limits in perception  The participants do not see the stimuli 2) These studies may reveal limits in memory  The participants see the stimuli but immediately forget what they have just seen • One way to approach this hinges on when the perceiver selects the desired input and when the perceiver ceases the processing of the unattended input • There are two hypothesis to explain this: 1) Early selection hypothesis  The attended input is identified and privileged from the start  The unattended input receives little analysis and is thus never perceived • The input falls out of the stream of processing at an early stage • Neurological evidence: Recording from neurons inArea V4 of the visual cortex shows that the neurons are more responsive to attended than unattended ones 2) Late selection hypothesis  All inputs receive relatively complete analysis  Only the attended input reaches consciousness and thus it is the only one remembered • For instance, the Muller-Lyer illusion is an example of this because the participant is unaware of the illusion but they are influenced by it • Attention can literally change what we perceive • Why does the data sometimes indicate late selection and sometimes early? The answer depends on the nature of the input o Early selection  If the attended input is complex, the processing will demand more effort and a lot of cognitive resources  Little effort and processing is left over for other stimuli (unattended input) o Late selection  If the attended input is simple, the processing will demand fewer resources  This leaves more processing/effort available for the unattended input Selective Priming • Recognition requires a network of detectors and these detectors fire most readily/quickly if they are suitably primed • Priming o Is produced by one’s visual experience—specifically, whether each detector has been used recently or frequently in the past o Comes from another source: your expectation about what the stimuli will be • People can literally prepare themselves for perceiving by priming the suitable detectors o You must spend some effort or allocate some resources in order to do the priming o These resources are limited in supply • This simple idea helps explain several findings we’ve already met o Why don’t participants notice the shapes in the in-attentional blindness study?  They may not expect any stimulus, so they have no reason to be prepared for any stimulus  As a result, the stimulus, when presented falls on unprepared/unresponsive detectors o Selective listening  Since the participants do not want to listen to the distractor, they do not allocate resources to do so  The detectors needed for the distractor have no resources and are unprimed o Why does attention ‘leak’during selective listening tasks, and we hear some of the unattended stimulus, such as when you hear your name?  Detectors for this stimulus are already primed because you have often encountered this stimulus in the past  The activation level of these detectors are already high Two Types of Priming • Resources are needed to prime detectors and those resources are limited in supply • The Posner and Snyder experiment follows • Showed participants a pair of letters on a computer screen • Participants had to decided quickly, whether the letters were the same or different • Awarning signal was shown to notify participants that the stimuli was about to arrive, but provided no further information Low Validity High Validity Neutral Low + Neutral High + Neutral Warning Signal Primed Low + Primed High + Primed Warning Signal Misled Low + Misled High + Misled Warning Signal • There are several conditions: o Warning signal  Neutral: the warning signal was a plus sign (+)  Primed: the warning signal was a letter that matched the stimuli to come and acted as a primer  Misled: the warning signal was a letter that did not match the stimuli to come and was misleading o Validity  Low validity condition: the warning signal was a poor predictor of the upcoming stimulus by 20%  High validity condition: the warning signal was an excellent predictor of the upcoming stimulus by 80% • Accuracy rates were high, but the speed of responding varied o If we compare the primed and the neutral conditions, was there any benefit from the priming? o If we compare the misled and the neutral conditions, was there any cost from being misled? • Let’s consider the validity conditions: o In the low-validity condition  The participants cannot use the prime as a basis for predicting the stimuli because it is a poor predictor  Primes in this condition should not lead to any specific expectations, but does have a warm-up effect • Also known as stimulus-based primes  We still expect better response times in the primed than neutral condition o In the high-validity condition  The participants can use the prime as a basis for predicting the stimuli because it is an excellent predictor  Primes in this condition should lead to expectations and a warm-up effect • Also known as stimulus-driven primes • Results o Low-validity condition  Response times (RT) were faster in the primed conditions than in the neutral condition  Misleading had no effect performance and was the same as the neutral condition and as quick o High-validity condition  High-validity primes helped participants more than low-validity primes  In the misled condition, responses were slower than responses in the neutral condition—it hurt performance Explaining the Costs and Benefits • There are two types of primes: o Stimulus-based primes  Produced merely by the presentation of the priming stimulus  Has no role for expectations o Stimulus-driven/expectation-based primes  Is created only when the participant believes the prime allows a predication of what’s to come  Leads to poorer performance when the participant expects one outcome but another occurs Stimulus-Based Primes Stimulus-Driven/ Expectation-Based Primes Magnitude • Smaller • Larger, leading to a greater benefit in RT data Time • Faster—can be observed • Slower—takes longer to kick immediately after priming in (1/2 second) Cost • Appears to be ‘free’ • Has a ‘cost’ o Can prime one o Priming the ‘wrong’ detector without taking detector takes away from the away from others others o Performance was hurt o Participants were less prepared • Spatial attention: our ability to focus on a particular position in space o The same results were shown with spatial attention o Participants were better prepared for any stimulus that appears in the primed position Attention as a Searchlight • Studies of spatial attention suggest that visual attention can be compared to a searchlight beam that can ‘shine’anywhere in the visual field o The ‘beam’marks the region of space for which one is prepared o Inputs within the beam are processed more efficiently and more swiftly o The beam can be narrow or wide o It can be moved about at will as one explores/attends to one aspects of the visual field or another o The beam refers to movements of attention, not eyes • This analogy is just another way of saying that a person is priming the relevant detectors for that stimulus o This priming allows the detectors to work more swiftly and more efficiently, promoting our perception of the input Attending to Objects, or Attending to Positions • Is this how attention works—do we pay attention to objects or positions in space? o Each view captures part of the truth • One line of evidence is from patients who suffer brain damage o Unilateral neglect syndrome  Caused by damage in the parietal cortex  Patients seem to ignore all inputs coming from one side of the body (left or right)  Damage from the right parietal lobe leads to neglect for the left side of space • Unilateral neglect syndrome supports a space-based account of attention o The afflicted patient seems insensitive to all objects within a spatially defined region—for instance everything on their left side of their focus • Experiment: o Patients with unilateral neglect syndrome were shown a barbell frame with two targets on the end:  Red on the right side (within their focus)  Blue on the left side (out of their focus) o The patients were sensitive to the red target (on the right) and missed the blue target (on the left) o The patients then watched as the barbell frame rotated  The red was now on the left side (out of their focus)  The blue was now on the right side (within their focus) o However, the patients were still more sensitive to the red target (now on the left)  When the barbell rotated, so did the patient’s focus of attention • To describe these patients we need a 2-part account 1) The symptoms of neglect syndrome reveals a bias: these patients neglect half of space 2) Once attention is directed towards a target, it is the target that defines the focus of attention  If the target moves, the focus moves with it  The focus of attention is object-based not space-based • Normal participants show a mix space-based and object-based attention o Evidence for this is in the Posner experiment o Participants can focus on a particular region of space in preparation for a stimulus, even if the stimulus has not yet appeared o With no object, the attention must be spatially defined • Attention is heavily influenced by object boundaries o Some studies haves shown participants displays with visually superimposed stimuli o Participants are still easily able to pay attention to one of these stimuli and ignore another Divided Attention • When you want to do multiple things at once, you divide your attention among various tasks o One’s ability to perform concurrent tasks is limited though o Why are some task combinations easier than others? • Perceiving requires resources that are limited in supply o The same is true for mental tasks, such as remembering, reasoning and problem- solving • Divided attention: one can perform concurrent tasks only if the sum of the tasks is within the ‘cognitive budget’ o For example, solving calculus requires some mental resources and so does reading a text o You have enough resources to do either one of these tasks by itself, but not enough for both The Specificity of Resources • Some mental resources do seem specialized and so are drawn on only by certain tasks o This is why it is more difficult to combine 2 verbal tasks or reading and listening at the same time o Both require resources that aren’t available • There are greater interference among similar tasks Identifying General Resources • Apparently, tasks as different as driving and talking compete with each other for some mental resource o However, we have no explanation for this interference o Expect possibly for a general resource supply • There are likely to be several task-general resources, with each contributing to the limits on whether we can divide attention between tasks • Some of the relevant mental resources are task-general and call on a variety of mental activities, which include: o Response selector o Mental effort o Working-memory capacity • Pashler and Johnston have proposed a mental mechanism that is required for selecting and initiating responses, including both physical and mental ones o This response selector plays a key role in coordination the timing of our various activities o It serves as a mental traffic cop, controlling which processes go forward at any moment in time o Divided attention often involves a system of ‘turn-taking,’where each task switches priority Executive Control as a Limited Resource • Adifferent type of general resource, required for many tasks, involves more global processes and is known as the ‘central executive’ o It includes processes needed for planning out various activities o It sets goals and priorities, chooses strategies and directs the function of many cognitive processes o It guides daily functioning through habits and prior associations • However, if we would like to break out of habits and act differently we need to overrule the action/strategy supplied by memory o We need to take steps to keep out current goal in mind o We want the goal, not the habit to guide our actions • Engle’s proposal is that executive control: o Is a task-general mental resource needed whenever someone wants to avoid interference from previous habit o This control provides 2 essential functions: 1) It works to maintain the desired goal in mind 2) It serves to inhibit automatic/habitual responses • People differ in how effective their executive control is o With some people literally having more control over their own thought processes Working Memory Capacity • People with larger working memory capacity (WMC) have an advantage in many tasks, including o Those that involve resisting distraction and resisting habit/reflex o Staying on task whenever they are working on something challenging o Likely to score higher on verbal tests or reading comprehension o Better at following directions, reasoning tasks and computer-language learning • The neural underpinnings of WMC and two other areas of the brain are involved in what is known as the executive control: o The prefrontal cortex is involved in goal maintenance  Damage in this area of the brain shows ‘goal neglect’ o Anterior cingulate is involved in detecting situations that call for two conflicting responses  It triggers increased activation in other areas of the brain to overcome the conflict Practice • There’s a close relationship between how complicated a task is and how resource- demanding it is • Driving in ordinary circumstances makes only a light demand on executive control and only occasionally demands on the response selector o However if driving is challenging, it calls for a heavier demand on these resources o This is the same for talking on the phone, and since it is unclear whether driving/talking conditions will worsen, it is best to avoid both  Ahigher demand on resources for either task, leads to dangerous conditions on the road, since less attention/resources are left to be given The Effects of Practice • Why are things so different after practice than before? • Mental tasks require resources, with the particular resources required and the amount of those resources required, dependent on the nature of the task o More practice requires fewer resources • Practice and the executive control o Early in practice  There is no habits to fall back on, since the task is new  As a result, the executive control is needed all the time o With practice  The person acquires a repertoire of habits  They rely more and more on routine thoughts and actions  This decreases the demand of the executive control • The same is true for response selector and practice o Early in practice  You have to decide what the first step of your performance should be, and then launch that step  The response selector is needed a lot for the selection and launching of each individual step o With practice, the response selector is needed less • With practice, tasks make smaller demands on mental resources Why Does Practice Improve Performance? • To do the tasks, you need to be able to divide your attention among the task’s parts and this is where practice comes in o Early in practice  The various parts of the a task will each require resources  This makes it impossible to think about all the task’s parts at once  Example: a novice tennis player must focus on how they toss the ball first o With practice  The elements of the task become easier, thereby freeing up resources for dealing with other elements of the same task  This allows the person to deal with multiple elements simultaneously, which is what skilled performance requires  Example: with swerving the ball mastered, the expert tennis player can focus on aim or strategy Automaticity • Practice diminishes the need for moment-by-moment control of the task • All of this has an important implication: o If, after practice, a task is no longer drawing on mechanisms that provide control, then the task is, in a sense, uncontrolled • Psychologists distinguished between 2 tasks of tasks: o Controlled tasks  Are typically novel tasks or tasks that require considerable flexibility o Automatic tasks  Are typically highly familiar and do not require flexibility  The task is approached with a well-learned routine or a sequence of responses  These tasks can be learned through practice, good advice or by a skilled teacher  This task does not need to be supervised/controlled  It requires few resources • Automaticity: an automatic task that is usually easy and readily combined with other tasks o It has a downside:Automatic tasks can act like ‘mental reflexes’ • An example of the downside of automaticity is shown in an effect known as: stroop interference o Participants are shown a series of words and sked to name aloud the colour of the ink used for each word o The trick is that the words themselves were colour names o So people might see the word “BLUE” printed in green ink and would have to say ‘green’aloud o This task is enormously difficult since participants have a tendency to read the printed words themselves rather than naming the ink colour  This is because word recognition is very well practiced and proceeds automatically Where Are the Limits? • Selective and divided attention becomes more complicated in 2 regards: 1) There seem to be different types of resources 2) The exact resource demand of a task depends on several different factors, such as a) The nature of the task b) The novelty of the task c) How much flexibility the task requires • Attention is an achievement o An achievement of performing multiple activities simultaneously o An achievement of successfully avoiding distracting when you wish to focus on a single task o It rests on many skills, mechanisms and capabilities Chapter 5: The Acquisition of Memories and the Working­Memory System • Acquisition: the process of placing new information into long-term memory • Storage: the state in which a memory, once acquired, remains dormant until it is retrieved • Retrieval: the process of locating information in memory and activating that information for use • Memory works the same as a computer: o Acquisition phase: Information is provided to a computer o Storage phase: the information that resides in some dormant form, generally in the hard drive o Retrieval phase: the information is brought back from this dormant form, often via a search process that hunts through the desk The Route into Memory • Information processing: o Complex mental events such as learning, remembering, or deciding, which involve a large number of discrete steps o These steps occur one by one, each with its own characteristics and its own job to do, and with each providing as its ‘output’the input to the next step in the sequence • Agreat deal of information-processing theory focused on the processes through which information was detected, recognized and entered into memory storage o That is the process of information acquisition o An early version of this model was described by Waugh and Norman, which was later refined byAtkinson and Shiffrin o The model is known as the modal model The Modal Model • According to the modal model, information processing involves different kinds of memory: o Short-term memory o Long-term memory • Short-term memory: o Holds on to information currently in use o Is limited in how much it can hold o Is instantly and easily available to you o Working memory: a term to emphasize the function of this memory  All mental tasks rely on working memory, because they all involve inputs/sequences of steps that are stretched out in time  This creates a short-lived memory demand  It provides a mental ‘desk space’—a resource that lets you hang onto ideas, images, and memories while you are working on them • Long-term memory: o Memory that is much larger o It includes information that you are not thinking about right now and still part of your knowledge base o It contains all the information you remember Working Memory and Long­Term Memory: One Memory or Two? • Free recall: participants are asked to repeat back as many words as they can o They are free to report the words in any order they choose • Primacy effect: remembering the first few words on the list • Recency effect: remembering the last few words on the list • The primacy and recency effect is illustrated with a U-shaped curve describing the relation between position within the series (serial position) and likelihood of recall o The serial-position curve is easily explained by the modal model o Beginning of the curve—Primacy effect  The participants are thinking about the words they are hearing during the list presentation  These words are in their working memory o Dip in the curve  Working memory is limited in size  As participants try to keep up with the list presentation, they will be placing the words just heard into working memory and bumping previous ones out o End of the curve—Recency effect  The last few words on the list don’t get bumped out of working memory, since no further input arrives to displace these words • According to the modal model, the transfer of material from working memory to the long-term memory (LTM) depends on processes that require time and attention o Memory rehearsal: the process when you hear a word and repeat it over and over again o The first few items on the list are privileged  The first word “bicycle” was the only word to worry about, so participants were able to focus 100% of their attention on it  The second word “artichoke” received 50% of the participant’s attention  And so on, with each new word receiving less attention since their attention must be divided between more words o The primacy effect is the observed memory advantage for the early list items  Since the first items didn’t have to share attention with other words they received more rehearsal time and are more likely to be transferred to LTM  This makes them more likely to be recalled after a delay • The serial-position curve leads to further predictions 1) The model claims that the recency portion of the curve is coming from working memory, while the other items on the list are being recalled from LTM  This means that any manipulation of working memory should affect the recency items, but not recall of the other items on the list • How can we test this claim? How about by ridding ourselves of the recency effect • To do this, participants were asked to count backwards by a multiple of 3 (for instance), which eliminates the recency effect by taking all the resources of the working memory 2) The model claims that the rest of the curve, not including the recency portion, is coming from the LTM  This means that any manipulation should affect all performance expect for recency • We can test this claim by slowing down the presentation of the list • Participants have more time to spend on all list items, which increases the likelihood of transfer into the LTM • This should not influence working-memory performance or improve the recency effect • Other variables that influence entry into LTM include: o Using more familiar or common words • fMRI scans suggest that o Memory for early items on the list depends on the hippocampus and are associated with LTM o Memory for later items on the list do not show this pattern A Closer Look at Working Memory The Function of Working Memory • People with larger working memory capacity (WMC) have an advantage in many tasks, including o Those that involve resisting distraction and resisting habit/reflex o Staying on task whenever they are working on something challenging o Likely to score higher on verbal tests or reading comprehension o Better at following directions, reasoning tasks and computer-language learning The Holding Capacity of Working Memory • The capacity of someone’s working memory is measured with a digit-span task o In this task, people are read a series of digits and must immediately repeat them back o If successful, they are given a slightly longer list o If they can repeat this one without error, they’re given another one and so on o This continues until the person starts to make errors o Errors usually occur at 7-8 items  Also known as 7 plus-or-minus 2 items • What exactly is an item? o Miller proposed that working memory holds 7 plus-or-minus 2 chunks o Chucks: is not a fixed quantity but largely depends on the individual • The flexibility in how people ‘chunk’information can be easily seen in a span test o In this task individuals are asked to recall a long list of letters o Individuals can either memorize the individual letters, or created meaningful syllables  For instance, they can memorize: H, O, P, T, R,Aor memorize HOP, TRA  This way they can hold onto more letters • The chunking process does have advantages and disadvantages: o Advantage: creates considerable flexibility in what working memory can hold o Disadvantage: since the effort/attention that is required to ‘repackage’the materials, there is less attention/effort for rehearsing these items The Active Nature of Working Memory • Working memory is like the office of a busy librarian who is energetically categorizing, cataloguing and cross-referencing new material • The traditional span test is designed to count the number of ‘slots’in working memory, with each new item on the test being placed in its own slot o This method does little to measure working memory’s capacity to do things with these slots o This led researchers to develop more dynamic measures of working memory o Such as operation span: designed specifically to measure the efficiency of working memory when it is ‘working’ • An example of operation span includes the following experiment: o Participants were asked to read 2 sentences out loud and recall the last words of these sentences o More correct answers meant more sentences were added o This task involves:  Storing some materials (the ending words) for later recall  While, working with other materials (the full sentence) • Working memory is not a passive storage box, but it is instead a highly active information processor The Working­Memory System • Working memory is a system built out of several components • At the center of the system is the central executive: o Amultipurpose processor capable of running many different operations on many different types of materials o Essentially it does the real ‘work’in working memory • Working memory ‘helpers’: o Store information you need soon but not right now o They maintain stored information o Examples of these helpers include:  Visuo-spatial Entering Long­Term Storage: The Role of the Intent to Learn Two Types of Rehearsal • Maintenance rehearsal: o The person simply focuses on the to-be-remembered items themselves, with little thought about what the items mean or how they are related to each other o Routine, mechanical process o Recycling items in working memory, simply repeating them over and over • Relational/Elaborative rehearsal: o The person thinks about what the to-be-remembered items mean and how they’re related to each other and to other things you already know Incidental Learning, Intentional Learning, and Depth of Processing • Incidental vs. Intentional learning o Incidental learning: learning in the absence of any intention to learn o Intentional learning: learning that is deliberate, with an expectation that memory will be tested later on • Depth of processing o Shallow processing:  Person engaged the material in a superficial fashion.  Ex. They had to say whether the word was in capital letters or not, red or green, high or low on the screen, etc. o Deeper processing:  Person puts some thought about what the word means  Amore thorough depiction and understanding The Role of Meaning and Memory Connections • Memory performance is roughly the same in conditions in which participants do shallow processing with an intention to memorize, and conditions in which they do shallow processing, without this intention • Likewise, the outcome is the same whether people do deep processing with the intention to memorize, or without the intention to memorize Organizing and Memorizing • Organization promotes memory Mnemonics • Mnemonics: Increase one’s ability to remember more accurately o Ex. ROY G BIV – colors of the rainbow o Ex. Every good boy deserves fudge – music lines in a treble cleft • Other mnemonics involve the use of mental imagery, relying on mental pictures o Can’t be just random, need specific meaning • Adifferent type of mnemonic provides an external “skeleton” for the to-be-remembered materials o Peg-word systems: these begin with a well-organized structure such as:  One is a bun. Two is a shoe. Three is a tree. Four is a door. Five is a hive. Six are sticks. Seven is heaven. Eight is gate.  This rhyme provides “peg words” and in memorizing something you can “hang” the materials to be remembered on those “pegs” Chapter 6: Interconnections between Acquisition and Retrieval Learning as Preparation for Retrieval • Retrieval Paths: when you want to locate information in memory, you travel on those paths, moving from one memory to the next until you reach the target material Context­Dependent Learning • New material learned is most likely to be recalled when the person is in the same context as when the material was learned o Example: The scuba divers learning material underwater and on land o Example: The students learning new material in a quiet or noisy environment • What matters the most: not the physical context but the psychological context o The students were able to write the test in a new room and performed well because they were asked to think about the room they initially studied the new material in Changes in your Approach to the Memory Materials • Context Reinstatement: recreating the context that was present during learning that will improve memory performance • Study: o Participants were given word pairs and were asked to remember the second word pair o The word pairs were related either through context words (“dog-cat”) or rhymed (“hat-cat”) o During the test either cues or hints were given o Two observations:  Depth Processing Effect: thinking about the meaning  Context Reinstatement effect: having the same kind of context during the learning and retrieval processes  Both were advantages • Connections lead to memory – the target material Encoding Specificity • Encoding Specificity- refers to the tendency when memorizing, to place in memory both the materials learned as well as the context of those materials o Materials will be recognized as familiar later on only if they are placed again in a similar context o BUT the context can change the meaning of what is to be remembered o Example: Piano example… “lifted” and “tuned” The Memory Network • Memory is thought of as a “vast network” of ideas • Representations are the “nodes” within the network (like the knots on a fisherman’s net) • These nodes are then tied to each other through con
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