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Midterm Textbook Notes

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Western University
Psychology 2135A/B
Olessia Jouravlev

Chapter 1: Cognitive Psychology: History, Methods, and Paradigms • Cognitive psychology  concerned with how people acquire, store, transform, use, and communicate information • Attention = cognitive resources, mental effort, or concentration devoted to a cognitive process • Perception = the interpretation of sensory information to yield a meaningful description or understanding • Pattern recognition = the classification of a stimulus into a category • Memory = the cognitive processes underlying the storage, retention, and retrieval of information • Recognition = the retrieval of information in which the processor must decide whether the information presented has been previously presented • Recall = the retrieval of information in which the processor must generate most of the information without aids • Reasoning = cognitive process(es) used in transforming information given, called premises, into conclusions  often seen as a special kind of thinking • Problem solving = cognitive process(es) used in transforming starting information into a goal state using specified means of solution • Knowledge representation = the mental depiction, storage, and organization of information • Language = a system of communication that is governed by a system of rules (a grammar) and can express an infinite number of propositions • Decision making = the process(es) by which an individual selects one course of action among alternatives • Scientists must know how to study a naturally occurring phenomenon with sufficient experimental rigor to draw firm conclusions o Isolate the phenomenon, and bring it into the lab o Narrow down what is essential and inessential about the phenomenon Influences on the Study of Cognition • Aristotle and Plato  wrote extensively on the nature of memory • John Locke, David Hume, George Berkeley, and John Stuart Mill  follow Aristotle (an empiricist view) • Rene Descartes and Immanuel Kant  follow Plato (a nativist position) • Empiricism = a philosophical doctrine emphasizing the role of experience in the acquisition of knowledge o Knowledge that comes from one’s own experience o Emphasizes human nature’s malleable aspects o Previous learning o Association of two ideas (linking them together in YOUR mind even if they might not normally go together for other people) • Nativism = a philosophical doctrine emphasizing the role of innate factors in the acquisition of knowledge o Emphasizes the role of constitutional factors o Biologically endowed capacities and abilities o “Hard-wired” functions (i.e. short-term memory) o Innate structures are present in at least rudimentary form at birth and are not learned, formed, or created as a result of experience Structuralism • Wilhelm Wundt  wanted to establish a “science of mind”, wanted to create a table of “mental elements” like the periodic table of elements o Book: Principles of Physiological Psychology • James Baldwin  first person to conduct controlled experiments with children • Introspection = a methodological technique in which trained observers are asked to reflect on, and report on, their conscious experience while performing cognitive tasks o Wundt thought any conscious thought or idea resulted from a combination of sensations that could be defined in terms of four properties: mode, quality, intensity, and duration • Structuralism = one of the earliest schools of cognitive psychology; it focused on the search for the simplest possible mental elements and the laws governing the ways in which they could be combined Functionalism • William James o The Principles of Psychology o Interested in conscious experience  not interested in the elementary units of consciousness o He assumed the way the mind works has a great deal to do with its function o Said habits as a mechanism basic to keeping our behaviour within bounds, said they were inevitable and powerful o Urged people to never an exception when trying to establish a good habit, to seize opportunities to act on resolutions, and to engage in a “little gratuitous effort” every day to keep the “faculty of effort” alive • Functionalism = a school of psychology emphasizing questions such as why the mind or a particular cognitive process works the way it does • Functionalists drew heavily on Darwinian evolutionary theory and tried to extend biological conceptions of adaptation to psychological phenomena • Structuralists were convinced the proper setting for experimental psychology was the lab, where experimental stimuli could be stripped of their everyday meanings to determine the true nature of mind • Functionalists study mental phenomena in real life situations  basic belief: psychologists should study whole organisms in whole, real-life tasks Behaviourism • Behaviourism = a school of psychology that seeks to define psychological research in terms of observable measures, emphasizing the scientific study of behaviour • Many regard it as a branch of functionalism • Behaviourists rejected such techniques of study as introspection  they found it untestable • Watson: o According to behaviourists, psychology is a purely objective natural science o It’s theoretical goal is the prediction and control of behaviour • Why do behaviourists dislike introspection? o Subjective in nature o Because of it’s inability to resolve disagreements about theory • Watson regarded all “mental” phenomena as reducible to behavioural and physiologic responses • He found evidence showing that when people report they are “thinking”, muscles in the tongue and larynx are actually moving slightly • His contribution to cognitive psychology was largely negative as he believed that the scientific study of mental phenomena was simply not possible • B. F. Skinner  psychology’s best-known behaviourist  argued that such “mentalistic” entities as images, sensations, and thoughts should not be excluded simply because they are difficult to study – said they were proper objects of study • He objected to treating mental events and activities as fundamentally different from behavioural events and activities • Mental representations = an internal depiction of information o Internal copies of external stimuli • Skinner: even if mental events were real and separate entities, they were triggered by external environmental stimuli and gave rise to behaviours • Asimple functional analysis of the relationship between the stimuli and behaviours would avoid the well-known problems of studying mental events Gestalt Psychology • Gestalt psychology = a school of psychology emphasizing the study of whole entities rather than simple elements; Gestalt psychologists concentrate on problems of perception and problem solving and argue that people’s cognitive experience is not reducible to their experience of simple elements (i.e. sensations) but, rather, to the overall structure(s) of their experience • Max Wertheimer, Kurt Koffka, and Wolfgang Kohler • Gestalt psychologists o Rejected structuralism, functionalism, and behaviourism o Chose to study people’s subjective experience of stimuli and to focus on how people use or impose structure and order on their experiences o Believed that the mind imposes its own structure and organization on stimuli and organizes perceptions into wholes rather than discrete parts The Study of Individual Differences • Individual differences = stable patterns of performance that differ qualitatively and/or quantitatively across individuals • Sir Francis Galton o Wondered whether intellectual talents could also be inherited o Noticed “intelligence” or “eminence” seemed to run in families o He studied mental imagery o Invented tests and questionnaires to assess mental abilities  still cited today o His statistical analyses allowed hypotheses to be rigorously tested The “Cognitive Revolution” • Cognitive revolution = a movement in psychology that culminated after World War II, characterized by a belief in the empirical accessibility of mental states and events • Anew series of psychological investigations • Mainly a rejection of the behaviourist assumption that mental events and states were beyond the realm of scientific study or that mental representations did not exist • Human factors engineering = an applied area of research that focuses on the design of equipment and technology that is well suited to people’s cognitive capabilities • Person-machine system = idea that machinery operated by a person must be designed to interact with the operator’s physical, cognitive, and motivational capacities and limitations • Limited-capacity processors = a system that acquires, stores, manipulates, and/or transmits information but has fixed limits on the amount or rate of processing that it can accomplish • George Miller  observed that (a) the number of unrelated things we can perceive distinctly without counting, (b) the number of unrelated things on a list we can immediately remember, and (c) the number of stimuli we can make absolute discriminations among is 5-9 for most normal adults • Linguistics = a field of study focusing on the structure, use, and acquisition of language • Noam Chomsky o His early work  showed that behaviourism could not adequately explain language o Parents don’t correct their children’s formation of language, they just typically judge the content o He argued that underlying people’s language abilities is an implicit system of rules, collectively known as a generative grammar  these rules allow speakers to construct, and listeners to understand, sentences that are “legal” in the language o He believed the rules operate implicitly: we don’t necessarily know exactly what all the rules are, but we use them rather easily to produce understandable sentences and to avoid producing gibberish • Neuroscience  study of the brain-based underpinnings of psychological and behavioural functions • Localization of function = the “mapping” of brain areas to different cognitive or motor functions; identifying which neural regions control or are active when different activities take place • Karl Lashley  claimed there was no reason to believe that major functions (i.e. language, memory) are localized • Donald Hebb  suggested that some kinds of functions were constructed over time by the building of cell assemblies (connections among sets of cells in the brain) • Hubel and Weisel  demonstrated the importance of early experience in nervous system development (they did research on cats) • Computer metaphor = the basis for the information-processing view of the brain; different types of psychological processes are thought to be analogous to the workings of a computer processor o People and computers often need to recode information  change the way it is recorded or presented o Must also manipulate information in other ways • Artificial intelligence = a branch of computer science concerned with creating computers that mimic human performance on cognitive tasks Current Trends in the Study of Cognition • Cognitive science = an interdisciplinary field drawing on research from cognitive psychology, computer science, philosophy, linguistics, neuroscience, and anthropology; the central issues addressed involve the nature of mind and cognition and how information is acquired, stored, and represented • Gardner  pointed out that the field of cognitive science rests on certain common assumptions o Cognition must be analyzed at what is called the level of representation o Cognitive scientists focus on representations of information rather than on how nerve cells in the brain work or on historical or cultural influences • Cognitive neuropsychology = a school of psychology that investigates the cognitive abilities and deficits of people with damaged or otherwise unusual brain structures • Vision for action and vision for perception are based on different neural substrates, and thus can function somewhat independently Summary • Structuralism  what are the elementary units and processes of the mind? • Functionalism  focus on the larger purposes and contexts that cognitive processes serve • Behaviourists  challenge psychologists to develop testable hypotheses and to avoid unresolvable debates • Gestalt psychologists  say an understanding of individual units would not automatically lead to an understanding of whole processes and systems • Galton  individuals can differ in their cognitive processing Research Methods in Cognitive Psychology Naturalistic Observation • Naturalistic observation = a research paradigm in which an observer observes participants in familiar, everyday contexts while ideally remaining as unobtrusive as possible • Ecological validity = a property of research such that the focus of study is something that occurs naturally outside an experimental lab • Experimental control = a property of research such that the causes of different behaviours or other phenomenon can be isolated and tested; typically, this involves manipulating independent variables and holding constant all factors but the one(s) of interest • An observer’s recordings are only as good as her initial plan for what is important to record o People she chooses to observe, behaviours and actions she chooses to record, manner of recording, and duration/frequency of observation all influence the results and conclusions drawn later Introspection • Discussed above • Has all the benefits and drawbacks of other observational studies, plus more • Pro: observing yourself gives you better insight into an experience and the factors that influenced it yielding a richer, more complete picture • Con: you are biased toward yourself, and you may be motivated to subtly and unconsciously distort your observations Controlled Observation and Clinical Interviews • Controlled observation = a research paradigm in which an observer standardizes the conditions of observation for all participants, often introducing specific manipulations and recording responses • Clinical interviews = a research paradigm in which an investigator begins by asking participants a series of open-ended questions but follows up on the responses with specific questions that have been prepared in advance o Depends on how the participant responds  can go any way they determine Experiments and Quasi-Experiments • Experiment = (true experiment) a test of scientific theory in which the researcher manipulates the independent variable and observes how the recorded measures (dependent variables) change as a result • Between-subjects design = a research paradigm in which different experimental subjects participate in different experimental conditions o i.e. group 1 in condition 1, and group 2 in condition 2 • Within-subjects design = a research paradigm in which the same experimental subjects participate in different experimental conditions o i.e. group 1 in condition 1AND condition 2 • Quasi-experiments = an empirical study that appears to involve some, but incomplete, experimental control – for example, through nonrandom assignment of subjects to conditions • The lab setting or the artificiality or formality of the task may prevent research participants from behaving normally Investigations of Neural Underpinnings • Brain imaging = the construction of pictures of the anatomy and functioning of intact brains through such techniques as computerized axial tomography (CAT or CT), positron emission tomography (PET), magnetic resonance imaging (MRI), or functional magnetic resonance imaging (fMRI) Summary • First, cognitive psychologists use a variety of approaches to study cognitive phenomena • Second, no research design is perfect – each has benefits and limitations Tradition Name Question Method Individual Galton How do people Tests, statistical differences differ? analysis Physiology Hebb What kinds of Tests, observations, disruptions autopsy accompany specific kinds of brain damage? Structuralism Titchener What are the basic Introspection under building blocks of controlled consciousness? conditions Functionalism James Why does the mind Introspection under have the operations naturalistic it has? conditions Gestalt psychology Koffka What organization Introspection under does the mind controlled impose on different conditions configurations of simple stimuli? Behaviourism Skinner How is behaviour Observation under affected by context? controlled conditions Human factors Broadbent What leads to Observation under engineering maximally efficient controlled use of a machine by conditions a person? Paradigms of Cognitive Psychology • Paradigm = a body of knowledge that selects and highlights certain issues for study; it includes assumptions about how a particular phenomenon ought to be studied and the kinds of experimental methods and measures that are appropriate to use  intellectual frameworks that guide investigators in studying and understanding phenomena The Information-Processing Approach • Information-processing approach = an approach to cognition that uses a computer metaphor in its explanations; information processing equates cognition with the acquisition, storage, and manipulation of information (for example, what we see, hear, read about, think about) through a system consisting of various storage places and systems of exchange • Researchers in this approach suggest that information is processed in stages and that it is stored in specific places while being processed • People’s cognitive abilities can be thought of as “systems” of interrelated capacities • This approach is used to explain how individuals go about performing specific cognitive tasks • Information-processing theorists assume that people are general-purpose symbol manipulators  can perform astonishing cognitive feats by applying only a few mental operations to symbols • This model is depicted best by something computer scientists call flowcharts, which illustrate the sequential flow of information through a system • This approach is rooted in structuralism – it’s followers attempt to identify the basic capacities and processes we use in cognition • Information-processing psychologists use experimental and quasi-experimental techniques in their investigations The Connectionist Approach • Connectionism = an approach to cognition emphasizing parallel processing of information through immense networks of interconnected nodes; models developed in the connectionist tradition are sometimes declared to share certain similarities with the way collections of neurons operate in the brain; hence, some connectionist models are referred to as neural networks • Also called parallel-distributed processing, or PDP • The exact level of activation depends on the input to that unit from both the environment and other units to which it is connected • Connections between 2 units have weights, which can be positive or negative o Apositively weighted connection causes one unit to excite or raise the level of activation of units to which it is connected o Anegatively weighted connection has the opposite effect  inhibiting or lowering the activation of connected units • One major difference between the information-processing and the connectionism approaches is the manner in which cognitive processes are assumed to occur o In information-processing models, cognition is typically assumed to occur serially – in discrete stages (first one process occurs, feeding information into the next process, which feeds information to the next process, and so on) o Most (but not all) connectionist models assume that cognitive processes occur in parallel, many at the same time • All connectionist models share the assumption that there is no need to hypothesize a central processor that directs the flow of information from one process or storage area to another  instead, different patterns of activation account for the various cognitive processes • Knowledge is not stored in various storehouses but within connections between units • Feldman and Ballard  argued that this approach is more consistent with the way the brain functions o “The fundamental premise of connectionism is that individual neurons do not transmit large amounts of symbolic information, instead they compute by being appropriately connected to large numbers of similar units…” o “Connectionism seeks to replace the computer metaphor…with a brain metaphor” • Connectionism draws from structuralism • However, connectionists look to cognitive neuropsychology and cognitive neuroscience for information • Connectionist models are more concerned with the “subsymbolic” level: how cognitive processes actually could be carried out by a brain • Most connectionist work seeks to replicate the findings of experimental and quasi-experimental research using computer programs based on a neural-network model The Evolutionary Approach • The human mind is a biological system, one that has evolved over generations • Human mind has responded to evolutionary pressures to adapt in certain ways rather than others in response to the environments encountered by our predecessors • Humans have specialized areas of competence produced by our evolutionary heritage • Cosmides and Tooby  argued that people have “a large and heterogeneous set of evolved, reliably developing, dedicated problem-solving programs, each of which is specialized to solve a particular domain or class of adaptive problems (i.e. grammar acquisition, mate acquisition, food aversion, way finding)” o Special-purpose mechanisms specific to a certain context or class of problems • Evolutionary psychologists predict that people’s reasoning will be especially enhanced when they are reasoning about cheating • Evolutionary psychologists believe we understand a system best if we understand the evolutionary pressures on our ancestors The Ecological Approach • This approach comes from both psychologists and anthropologists • Overlaps much more with evolutionary approach than with either the information- processing and connectionist approach • Ecological approach = an approach to the study of cognition emphasizing the natural contexts or settings in which cognitive activities occur, and the influences such settings have in the ways in which cognitive activities are acquired, practiced, and executed • We can see the influences of both the functionalist and the Gestalt schools on the ecological approach • Functionalists focused on the purposes served by cognitive processes • Gestalt psychology’s emphasis on the context surrounding any experience is likewise compatible with the ecological approach • The ecological approach would deny the usefulness (and perhaps even the possibility) of studying cognitive phenomena in artificial circumstances divorced from larger contexts • Thus this tradition relies less on lab experiments or computer simulations and more on naturalistic observation and field studies to explore cognition Summary • Information-processing approach  focuses researchers on the functional aspects of cognition • Connectionist approach  focuses on the underlying “hardware” • Evolutionary approach  how a cognitive system or function has evolved over generations • Ecological approach  stresses the need to consider the context of any cognitive process to understand more completely how that process functions in the real world • Some research incorporates parts of different paradigms, some fits no paradigm Chapter 2: The Brain:An Overview of Structure and Function • Many cognitive psychologists feel they cannot investigate cognition without a working knowledge of how the brain develops and functions • Growth statistics: o Brain grows from 0 to 350 grams (3/4 of a pound) during the prenatal period (this growth doesn’t stop at birth) o At ~20 years, brain reaches max weight (1,350 grams = ~3 pounds) Structure of the Brain The Hindbrain and Midbrain • Hindbrain = part of the brain containing some of the most evolutionary primitive structures that is responsible for transmitting information from the spinal cord to the brain, regulating life support functions, and helping to maintain balance o Brain stem  consists of the medulla and pons in the hindbrain, as well as the midbrain and parts of the forebrain o The hindbrain has three major structures  Medulla oblongata = (aka the medulla) transmits information from the spinal cord to the brain and regulates life support functions such as respiration, blood pressure, coughing, sneezing, vomiting, and heart rate  Pons = a neural relay center, facilitating the “crossover” of info between the left side of the body and the right side of the brain (and vice versa) – also involved in balance and processing of both visual and auditory information  Cerebellum = part of the brain that controls balance and muscular activity, as well as general motor behaviour and coordination – one of the most primitive brain structures • Brain lesions in cerebellum  irregular and jerky movements, tremors, and impairment of balance and gait • Implicated in people’s ability to shift attention between visual and auditory stimuli, and in dealing with temporal stimuli (i.e. rhythm) • Midbrain = part of the brain containing structures that are involved in relaying information between other brain regions, or in regulating levels of alertness o Contains the inferior and superior colliculi o Also involved in sudden arousal we may need to respond to a threatening or attention-grabbing stimulus The Forebrain • Forebrain = part of the brain containing the thalamus, hypothalamus, hippocampus, amygdala, and the cerebral cortex o Thalamus = structure in the forebrain involved in relaying information, especially to the cerebral cortex o Hypothalamus = controls the pituitary gland by releasing hormones  Also controls so-called homeostatic behaviours (i.e. eating, drinking, temperature control, sleeping, sexual behaviours, emotional reactions) o Hippocampus = involved in the formation of long-term memories o Amygdala = modulates the strength of emotional memories and is involved in emotional learning o Basal ganglia  are involved in the production of motor behaviour o Cerebrum  largest structure in the brain  Cerebral cortex = the surface of the cerebrum, the largest structure of the brain, containing both sensory and motor nerve cell bodies • Consisting of about half-dozen layers of neurons with white matter beneath • Carries information between the cortex and the thalamus or between different parts of the cortex  Cerebral cortex is divided into four lobes (and each lobe is divided in two – the left and right): • Frontal lobe = division of the cerebral cortex located just beneath the forehead containing the motor cortex, premotor cortex, and the prefrontal cortex • Parietal lobe = a division of the cerebral cortex located at the top rear part of the head; contains the primary somatosensory cortex • Occipital lobe = a division of the cerebral cortex located at the back of the head that is involved in the processing of visual information • Temporal lobe = a division of the cerebral cortex located on the side of the head, involved in the processing of auditory information and in some aspects of memory  The left and right hemispheres are connected by the corpus callosum (in the case of the frontal, parietal, and occipital lobes) and the anterior commissure (in the case of the temporal lobes)  Central sulcus  a prominent shallow groove on the surface of the brain • Divides the frontal and parietal lobes  Lateral sulcus  helps define the temporal lobe  Parietal lobes contain the somatosensory cortex, which is contained in the postcentral gyrus, the area behind the central sulcus • Gyrus  a convolution or ridge of the brain • Involved in the processing of sensory information from the body (i.e. sensations of pain, pressure, touch, temperature)  Occipital lobes process visual information  Temporal lobes process auditory information, as well as the ability to reorganize certain stimuli such as faces • Because of where it is located, damage to the temporal lobes can result in memory disruption  Frontal lobes have three separate regions: • Motor cortex = a structure in the frontal lobe (specifically, the precentral gyrus) that controls fine motor movement • Premotor cortex  involved in planning such movements • Prefrontal cortex = a region in the frontal lobe that is involved in executive functioning o Executive functioning = planning, making decisions, implementing strategies, inhibiting appropriate behaviours, and using working memory to process information o Damage to prefrontal cortex  marked changes in personality, mood, affect, and the ability to control inappropriate behaviour o Has the longest period of maturation, but also the first to go in aging effects Localization of Function • Localization of function = the “mapping” of brain areas to different cognitive or motor functions; identifying which neural regions control or are active when different activities take place • Franz Gall o Faculty psychology = theory that different mental abilities (i.e. reading or computation) were independent and autonomous functions, carried out in different parts of the brain • Johan Spurzheim o Gall’s student o Phrenology = (now discredited) idea that psychological strengths and weaknesses could be precisely correlated to the relative sizes of different brain areas o Problems with phrenology  The size of the portion of the brain does not correspond to its relative power  Different faculties are not independent • Paul Broca o Aphasia = a result of brain injury to a particular part of the frontal lobe, causing a disruption of expressive language o This brain region is known as Broca’s area  damage to this area causes Broca’s aphasia, or nonfluent aphasia, where the person is unable to produce many words or speak very fluently • Carl Wernicke o Found another language centre thought to control language understanding instead of language production o Called Wernicke’s area, located in the superior posterior region of the temporal lobe o Patients with Wernicke’s aphasia (or fluent aphasia) are able to produce speech (with proper pitch and rhythm) but their speech often makes no sense and contain gibberish  These patients show impairments in their ability to understand speech • Primary somatosensory cortex = a region of the parietal lobe involved in the processing of sensory information from the body o It is organized such that each part of it receives information from a specific part of the body o Alarge region of the body (i.e. a leg) corresponds to only a small portion of the primary somatosensory cortex, but a more sensitive body part (i.e. fingers, lips) has a correspondingly larger amount of cortex devoted to it • Wilder Penfield o Stimulated the brain with electrical probes while patients were conscious (under local anesthesia) and observed their responses o He created maps of the sensory and motor cortices of the brain (these maps are still used today) • Karl Lashley o Ablation = removal of cells or tissues, often through surgical means o While basic cognitive functions seems to rely on particular brain regions, some more complex cognitive functions likely rely on a combination of regions that must interact to produce function o Plasticity = the ability of some brain regions to “take over” functions of damaged regions  The younger the patient and less extensive the injury, the more likely they will be able to regain function Lateralization of Function • Lateralization = specialization of function of the two cerebral hemispheres • Most individuals show a specialization for language in the left hemisphere • In these individuals, the left hemisphere is larger in size, especially in the areas where language is localized o Say that these individuals have a left-hemisphere dominance in language • Small percentage of people do not show such specialization, having language in both hemispheres (bilateralized individuals) • Even smaller percentage have language centres located in the right hemisphere • Structurally, the right hemisphere often has larger parietal and temporal areas  leads to better integration of visual and auditory information and better spatial processing • Right hemisphere associated with working on geometric puzzles, navigation around familiar spaces, and musical ability • Left hemisphere  analytical o Good at processing information serially (events occurring one after another) • Right hemisphere  synthetic o Putting individual elements together to make up a whole o i.e. constructing maps or other spatial structures, drawing sketches, and navigating through mazes • Corpus callosum = the large neural structure containing fibers that connect the right and left cerebral hemispheres o Sends info from one hemisphere to the other very quickly Brain Imaging Techniques • Brain imaging techniques = the construction of pictures of the anatomy and functioning of intact brains through such techniques as computerized axial tomography (CAT or CT), positron emission tomography (PET), magnetic resonance imaging (MRI), or functional magnetic resonance imaging (fMRI) • Computerized axial tomography (CAT or CT) = an imaging technique in which a highly focused beam of x-rays is passed through the body from many different angles; differing density of the organs of the body result in different deflection of the x-rays, which allows visualization of the organ o Takes pictures of 9-12 different “slices” of the brain o Can use CAT scans to pinpoint areas of damage and to see the relative “age” of the injury • Some animal research has involved placing electrodes in individual neurons to detect when and how often those single cells fire  not done on humans • Electroencephalography (EEG) = a technique to measure brain activity, specifically, to detect different states of consciousness; metal electrodes are positioned all over the scalp; the waveforms that are recorded change in predictable ways when the person being recorded is awake and alert, drowsy, asleep, or in a coma • Magnetoencephalography (MEG)  measures changes in magnetic fields generated by electrical activities of neurons o MEG gives a more precise localization of brain region activity than does EEG • Event-related potential (ERP) = an electrical recording technique to measure the response of the brain to various stimulus events o Electrodes attached to their scalp and they are presented with various external stimuli (i.e. sights or sounds) • Positron emission tomography (PET) = a brain-imaging technique that shows which areas of the brain are most active at a given point in time o Injecting a radioactively labeled compound o Measure the blood flow to different regions of the brain o Variation of the PET scan measures local metabolic changes instead of blood flow, using an injection of fluorodeoxyglucose, a radioisotope structurally similar to glucose o PET scans rely on the fact that when an area of the brain is active more blood flows to it, and its cells take up more glucose from the blood vessels that penetrate it o People undergoing a PET scan sit with their head in a ring of photocells o Aradioactive tracer is injected into a vein as water – within 30 seconds, the tracer starts to reach the brain o Within the ~2 min before the radioactive tracer decays to its half-life several scans can be made, showing the amount of blood flowing to that region o Single-photon emission computed tomography (SPECT)  another technique used to measure cerebral blood flow  Similar to PET but does not require the expensive equipment • Magnetic resonance imaging (MRI) = a body-imaging technique in which a person is surrounded with a strong magnetic field; radio waves are directed at a particular part of the body, causing the centres of hydrogen atoms in those structures to align themselves in predictable ways; computers collate information about how the atoms are aligning and produce a composite 3D image o Requires no radiation o Permits clearer images o People with pacemakers are not candidates for an MRI, nor are people with metal in their bodies o People with claustrophobia will struggle having an MRI o Now information is gathered about how a brain functions • Functional magnetic resonance imaging (fMRI) = an imaging technique that uses MRI equipment to examine blood flow in a noninvasive, nonradioactive manner o As blood is carried from the heart, it is maximally magnetic, BUT as it passes through capillaries, it becomes less magnetic • The mapping between physical activity in the brain and its functional state is such that when two experimental conditions are associated with different patterns of neural activity, it can be assumed that they have engaged distinct cognitive functions • Franciscus Donders  his idea was adapted to develop functional maps of cognitive processes in the brain o He measured the time it took a person to respond (by making a keypress) to a light and subtracted this from the time needed to respond to a particular colour of light o Subtraction technique = the idea that the relative amount of activation in a particular brain region needed for a given cognitive task can be measured by subtracting a control state (responding to a light) from a task state (discriminating colour) • Using these new methods of analysis of fMRI data, researchers are able to paint a clearer picture of how the human brain achieves cognitive processing • Summary! o CAT and MRI  yield neuroanatomical information o PET, SPECT, and fMRI  info about how blood flows during various cognitive activities o MEG, EEG, and ERPs  measure electrical activity during cognitive activities Chapter 3: Perceiving Objects and Recognizing Patterns • Perception = the interpretation of sensory information to yield a meaningful description or understanding • Perception can be subdivided: (1) visual perception, (2) auditory perception, (3) olfactory (smell) perception, (4) haptic (touch) perception, and (5) gustatory (taste) perception • Some psychologists (associated with James Gibson) would argue that you immediately acquire information about the object’s function when you perceive it • Distal stimulus = an object, event, or pattern as it exists in the world • Proximal stimulus = reception of information and its registration by a sense organ – i.e. retinal images in the case of vision • Retina = a layer of visual receptor cells at the rear of the eyeball • Retinal image = a proximal stimulus for vision, consisting of the projection of light waves reflected from stimuli and projected to a surface at the back of the eye o This image is 2D, upside down, and is reversed with respect to left and right • Percept = the outcome of a perceptual process; the meaningful interpretation of incoming information o Percepts are not the same things as proximal stimuli • Size constancy = the phenomenon that one’s perception of an object remains constant even as the retinal image of the object changes in size (i.e. because the object has moved closer or farther away from the perceiver) o Perception involves something different from the formation of retinal images • Pattern recognition = the classification of a stimulus into a category GestaltApproaches to Perception • Form perception = the process by which the brain differentiates objects from their backgrounds • Subjective contours = illusory outline created by certain visual cues that lead to erroneous form perception; the existence of this phenomenon suggests that perception is an active constructive process • The point is that this perception is not completely determined by the stimulus display; it requires the perceiver’s active participation • Max Wertheimer, Kurt Koffka, Wolfgang Kohler • Gestalt school of psychology was particularly concerned with how people apprehended whole objects, concepts, or units • The whole is not the same as the sum of its parts • Gestalt psychologists rejected the claim that we recognize objects by identifying individual features or parts; instead, we see and recognize each object or unit as a whole • Gestalt principles of perceptual organization = laws that explain the regularities in the way people come to the perceptual interpretations of stimuli; the emphasis is on the apprehension of whole structures rather than on the detection and assembly of parts of structures • 5 major principles (the real list is much longer) o Principle of proximity  we group things together that are nearer to each other o Principle of similarity  we group together elements that are similar o Principle of good continuation  we group together objects whose contours form a continuous straight or curved line o Principle of closure  mentally filling in the gap to see a closed, complete, whole figure o Principle of common fate  idea that elements that move together will be grouped together • Most of the Gestalt principles are subsumed under a more general law, the law of Pragnanz o This law states that of all the possible ways of interpreting a display, we will tend to select the organization that yields the simplest and most stable shape or form o i.e. simple and symmetric forms > complicated and asymmetric forms • Gestalt principles used by infants as young as 3-6 months • Some work on formalizing the Gestalt law of Pragnanz has begun with a new theory called minimal model theory Bottom-Up Processes • Bottom-up process = cognitive (usually perceptual) process guided by environmental input (also called data-driven process) o Perceiver starts with small bits of information from the environment that she combines in various ways to form a percept o You would form a perception from only the information in the distal stimulus • Top-down process = cognitive (usually perceptual) process directed by expectations (derived from context, past learning, or both) to form a larger percept, concept, or interpretation (also called conceptually driven or theory- driven process) o Your expectations guided where you looked, what you looked at, and how you put the information together • Bottom-up processes are relatively uninfluenced by expectations or previous learning (the so-called higher-level processes) • Posner and Raichle  argued that bottom-up processes involve automatic, reflexive processing that occurs even when the perceiver is passively regarding the information • There are 3 distinct examples of bottom-up models of perception: template matching, featural analysis, and prototype matching Template matching • Template = a stored pattern or model to which incoming information is matched in order to be recognized and classified • You can think of a template as a kind of stencil, only they work in reverse  an unknown incoming pattern is compared to all of the templates (stencils) on hand and identified by the template that best matches it • Template matching works like this: every object, event, or other stimulus that we encounter and want to derive meaning from is compared to some previously stored pattern, or template  the process of perception thus involves comparing incoming information to the templates we have stored, and looking for a match  if more than one template is CLOSE, we engage in further processing to sort out which template is most appropriate • This model implies that somewhere in our knowledge base we’ve stored millions of different templates • The problems: o Should we want a complete explanation, we would need to have stored an impossibly large number of templates o As technology develops and our experiences change, we become capable of recognizing new objects  template-matching models thus have to explain how and when templates are created and how we keep track of an ever-growing number of templates o People recognize many patterns as more or less the same thing, even when they differ • Template matching works only with relatively clean stimuli, for which we know ahead of time what templates may be relevant Featural analysis • Instead of processing stimuli as whole units, we might instead break them down into their components, using our recognition of those parts to infer what the whole represents • Feature = a component, or part, of an object, event, or representation • Recognition of a whole object depends on recognition of its features • Certain detectors appear to scan input patterns, looking for a particular feature • If that feature is present, the detectors respond rapidly • Each detector then appears designed to detect the presence of just one kind of feature in an input pattern • Such detectors exist in the form of either retinal or cortical cells • People use features to recognize letters • Visual search task = a task in which subjects are asked to detect the presence of a particular target against an array of similar stimuli • Similar findings have been reported for auditory perception of syllables that share many articulatory features • Selfridge  developed a model for the perception of letters that was based on featural analysis • Pandemonium = a model of letter perception based on a bottom-up hierarchy of feature detectors • Pandemonium works like this: you have a bunch of “demons” inside you that are basically “feature detectors” and there are different kinds of demons and they each have different types of responsibilities (in response to what each demon perceives, they scream, duh!)  first you have the image demon that perceives the letter that you are trying to detect (i.e.A) and then you have feature demons, and they start screaming out the specific features that they are responsible to look for, like “slanted line!” or “horizontal line!”, so the feature demons scream out the features they find that describe the image presented by the image demon (i.e. the A)  but remember, feature demons communicate their level of confidence by screaming more loudly or softly  so now, we have letter demons that listen for screams from the feature demons who scream out features that are associated with their letter, and then finally, one single decision demon listens to all these demons screaming and has to decide what letter is being perceived by the image demon, and will finally decide that it sees anA • Pandemonium outlines some important aspects of featural analysis: (1) real-life stimuli are often degraded or incomplete, yet objects and patterns can still be recognized, and (2) some features matter more than others in pattern recognition • The problems: (1) no definition of what can be a feature and what cannot, and (2) if there are different sets of features for different objects, how does the perceiver know which ones to use to perceive an object (remember, this must be decided before the perceiver knows what the object is)? If the same set of features applies to all objects, the list of possible features would appear huge Prototype Matching • This model attempts to correct some of the shortcomings of both template matching and featural analysis • Matching an input to a stored representation of information, as do template models • In this case, the stored representation, instead of being a whole pattern that must be matched exactly or closely, is a prototype • Prototype = an abstract representation of an idealized member of a class of objects or events • When a sensory device registers a new stimulus, the device compares it with previously stored prototypes • Exact match is not required, only an approximate match is expected • This model allows for discrepancies between the input and the prototype, giving prototype models a lot more flexibility than template models • An object is “perceived” when a match is found • Prototype models do not require that an object contain any one specific feature or set of features to be recognized • Instead, the more features a particular object shares with a prototype, the higher the probability of a match • Prototype models take into account not only an object’s features or parts but also the relationships among them • People can form prototypes surprisingly quickly Top-Down Processes • Context effect = the effect on a cognitive process (i.e. perception) of the information surrounding the target object or event; sometimes called expectation effect because the context is thought to set up certain expectations in the mind of the cognitive processor • Both accuracy and the length of time needed to recognize objects vary with the context • Top-down processes have to interact with bottom-up processes, otherwise, you would never be able to perceive anything you were not expecting and you would always perceive what you expected to perceive • David Marr  proposed that perception proceeds in terms of several different, special-purpose computational mechanisms, such as a module to analyze colour, another to analyze motion, etc. o Each operates autonomously, without regard to the input from or output to any other module, and without regard to real-world knowledge  thus they are bottom-up processes o He believed that visual perception proceeds by constructing three different mental representations (or sketches) o The primal sketch  depicts areas of relative brightness and darkness in a 2D image as well as localized geometric structure (this allows the viewer to detect boundaries between areas but not to “know” what the visual information “means”)  Once a primal sketch is created the viewer uses it to create a more complex representation, called a 2½D sketch  involves shading, texture, edges, etc.  Marr believed that both the primal sketch and the 2½D sketch rely almost exclusively on bottom-up processes o Final sketch is the 3D sketch  this involves both recognition of what the objects are and understanding of the “meaning” of the visual scene  This is where top-down processing comes in o Pointillism  the art where up close it looks like a bunch of little dots, but far away it forms a picture that is meaningful  Can see this using top-down processing Change Blindness • Change blindness = the inability to detect changes to an object or scene, especially when given different views of that object or scene • Atop-down processing phenomenon • Changes to the scene that don’t interrupt the “meaning” of he sequence don’t call attention to themselves • Our visual precepts are not precise copes of our visual world • Study: interviewer asked participant for directions and while the participant was helping them, two people carrying a big door walked through them and then the interviewers were changed o 50% of participants failed to notice the change in interviewer!! o Change in interviewer went undetected even though the two people were of different heights and builds, had different voices, and wore different clothes! o Student participants were more likely to notice the change than the older participants o But when the two interviewers donned construction worker clothing, fewer than half the students noticed the change • Change blindness paradigm reinforces the idea that perception does seem driven by expectations about meaning • We seem to represent the overall meaning of the scene instead of keeping track of little insignificant details • Rensink  to detect change, you must focus on the stimulus • Aginsky and Tarr  argue that some aspects of scene perception, such as presence and position of objects, automatically attract attention, where as other aspects of a scene, such as colour of objects, do not • Inattentional blindness  the inability to see what is directly in front of us unless we are paying attention The Word Superiority Effect • Word superiority effect = the phenomenon that single letters are more quickly identified in the context of words than they are when presented alone or in the context of random letters • Another top-down phenomenon • Research done using ERPs – participants asked which letter was presented and while they decided, ERPs were measured o Researchers showed that within 200ms of presentation of the crucial stimuli, the ERP measure was different for word as compared to nonword stimuli o Whether the stimulus was a word or a nonword was able to affect perception of the letter at a very early stage of processing • When asked to find all the fs in a sentence, more likely to find them in feature or function rather than of or for  as readers read connected text, they quickly divide words into content words (that have meaning) and function words (structure the content words) o They focus more attention on the moderately familiar content words and thus are likely to miss the letters in the highly familiar function words A Connectionist Model of Word Perception • This model assumes that input (written or visual) is processed at several different levels, whether in terms of features, letters, phonemes, or words • Phonemes = the smallest unit of sound that makes a meaningful difference in a given language • In this model, the different levels of processing feed into one another • The model assumes a different node for each distinct word, letter, and feature • When a node reaches a given level of activity, we can say that its associated feature, letter, or word is perceived • Connections between nodes can be excitatory or inhibitory o When an excitatory connection links two nodes, the two nodes suggest each other • Once a node is activated, that activation spreads along that node’s excitatory connections to other nodes • The assumption is that you can perceive only one word at any given instant • Perception of a word also activates the nodes corresponding to all the letters within the word, thereby facilitating their perception • Without the word context, the node for the individual letter is less active, so perception of the letter takes longer A Neuroscientific Perspective on Word Perception • Participants presented with 4 types of stimuli  true words, pseudowords (follow pronunciation rules but are not real words), letter strings (consonants with no vowels therefore not pronounceable), and false fonts (features of letters of the alphabet but not actually letters) • Words and pseudowords produced different PET scans from those produced when participants saw letter strings or false fonts • Different brain areas were active when the different types of stimuli were shown • All 4  saw activity in the visual cortexes of both hemispheres • With words and pseudowords  greater activity in the left than the right hemisphere and in regions outside the primary visual cortex (part of the brain that is involved in semantic processing – processing of stimuli for meaning) Direct Perception • Perceiver must acquire information about a distal stimulus, presumably by interpreting the proximal stimuli • Common assumption underlying the models of perception that were previously examined (especially top-down models) is that the perceiver does something to the proximal stimulus because the proximal stimulus doesn’t contain all the information we need to identify the object • Constructivist approach to perception = an understanding of perception as a process requiring the active construction of subjective mental representations not only from perceptual information, but from long-term memory as well • In this view, people are seen as active selectors, integrators, and constructors of information • James Gibson  said the opposite was true • Direct perception = theory of perception holding that information in the world is “picked up on” by the cognitive processor without much construction of internal representations or inferences (emphasis is on direct acquisition of information) • He believes that a person does very little work because the world offers so much information so there is no need to construct anything • In this view, the light hitting the retina contains highly organized information that requires little or no interpretation • Study  put light bulbs on people’s bodies, and watched them move in the dark  new what activity they were doing, and even if they were male or female! • Patterns of motion provide a great deal of information to the perceiver • Gibson  thought a lot about plane runways and landing a plane • Nearer things appear to move faster than things farther away, and the direction in which an object seems to move depends on the angle of the plane’s movement in relation to it • For Gibson, the central question of perception is not how we look at and interpret a stimulus array but rather how we see and navigate among real things in the world • Information available to an organism exists not merely in the environment but in an animal-environment ecosystem  animals continuously experience their environments • Different biological organisms have different perceptual experiences because they have different environments and different relationships with their environments • Affordance = a perceptual property of objects, places, and events that makes clear what actions or behaviours on the part of the perceiver are permitted in interaction with the object, place, or event o i.e. chair affords sitting o i.e. handle/knob affords grasping o i.e. glass window affords looking through • Gibson: affordances of an object are directly perceived; that is, we “see” a chair is for sitting just as easily as we “see” that a chair is one meter away or made of wood • Therefore, the reason we don’t crash into walls is because walls do not afford passing through • People argue that Gibson’s proposals are not well defined, and that he failed to specify what things are invariant and what are not • Someone proposed the idea of combining both direct perception and the constructionist view which was called the perceptual cycle o Schema = an organized framework for representing knowledge that typically includes characters, plots, and settings, and incorporates both general knowledge about the world and information about particular events o In the perceptual cycle, schemata guide the perceiver to explore the environment in particular ways, and the environment responds by confirming some expectations but not others Disruptions of Perception: VisualAgnosias • Visual agnosias = an impairment in the ability to interpret (but not to see) visual information) • Problem seems to lie in understanding what the visual pattern or object presented to them is • Patients with visual agnosias can’t recognize objects by sight, but may be able to recognize them by sound, touch, or smell • Apperceptive agnosia  people with this disorder are able to process a very limited amount of visual information o They can see the contours (or outlines) of objects, but have a very difficult time matching one object to another, or categorizing objects o Some cannot name objects at all • Associative agnosia  people with this disorder can match objects or drawings and copy drawing, but they tend to do so very slowly and very carefully, almost point by point o May become distracted by small details, such as a stray dot or a stray line on a drawing • Apperceptive agnosia is typically associated with one hemisphere (the right) • Associative agnosia is correlated with bilateral damage to a particular region of the brain (i.e. both hemispheres) • Some people can identify animate objects but cannot identify inanimate objects  adding to the mystery of visual agnosias • Prosopagnosia = a specific inability to recognize faces, even very familiar ones, with intact recognition of other objects o Caused by damage to a particular region in the right hemisphere o They can see details – like a person’s nose, or eyebrows, etc.  but they can’t put together a person’s features in a meaningful way to recognize them!! • Unilateral neglect (sometimes called hemineglect)  result of damage to the parietal cortex, and causes the patient to virtually ignore stimuli on the opposite side o i.e. someone with right-hemisphere parietal damage may fail to wash the left side of their body, comb the hair on the left side of their face, etc. Chapter 4: Paying Attention SelectiveAttention • Selective attention refers to the fact that we usually focus our attention on one or a few tasks or events rather than on many • This means we shut out other tasks going on around us
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