PS260 Chapter Notes (1-3)

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Wilfrid Laurier University
Sukhvinder Obhi

PS260 Chapter Notes Abigail Kaczmarek ▯ Chapter One: The Science of the Mind TheYears of Introspection • In Wundt’s and Titchener’s view, psychology needed to be concerned largely with the study of conscious mental events - feelings, thoughts, perceptions, and recollections • They concluded that the only way to study thoughts is for each of us to introspect, or “look within,” to observe and record the content of our own mental lives and the sequence of our own experiences • Introspectors had to be meticulously trained: They were given a vocabulary to describe what they observed; they were taught to be as careful and as complete as possible; and above all, they were trained simply to report on their experiences, with a minimum of interpretation • Enormously influential for several years • Forced to acknowledge that some thoughts are unconscious ▯ Introspection is the study of conscious experiences and so can tell us nothing about unconscious events ▯ Problem with Introspection: In order for any science to proceed, there must be some way to test its claims; otherwise, we have no means of separating correct assertions from false ones • Testability of claims is often unattainable • Imagine that I insist my headaches are worse than yours. How could we ever test my claim? ▯ TheYears of Behaviourism • An organisms behaviours are obviously observable in the right way:You can watch my actions, and so can anyone else who is appropriately positioned. Therefore, data concerned with behaviour are objective data, and thus grist for the scientific mill Stimuli in the world are in the same “objective” category: These are measurable, recordable, • physical events Learning history can also be objectively recorded and scientifically studied • ▯ Behaviourist Movement was a success in many ways and uncovered a range of principles concerned with how behaviour changes in response to various stimuli. • Late 1950’s psychologists were convinced that a great deal of behaviour could not be explained in these terms - that is, could not be explained with reference only to objective, overt events • The way in which people act, and the ways that they feel, are guided by how they understand or interpret the situation, and not by the objective situation itself. •What do these stimuli mean to you - Passing the salt example ▯ The Roots of the Cognitive Revolution • How people act is shaped by how they perceive the situation, how they understand the stimuli, and so on ▯ Immanuel Kant • Transcendental Method •Begin with observable facts and then work backward from these observations. •You ask: How could these observations have come about? What must the underlying causes be that led to these effects? •“Inference to best explanation” •Even though electrons themselves are not observable, their presence often leads to observable results - in essence, visible effects from an invisible cause •A size 11 footprint? That probably tells us what size feet the criminal has, even though no one observed his feet. ▯ Reproducing experiments and varying the experiments to test hypothesis - is what gives science its power ▯ Study mental processes indirectly, relying on the fact that these processes, themselves invisible, have visible consequences: measurable delays in producing a response, performances that can be assessed for accuracy, errors that can be scrutinized and categorized. • By examining these (and other) effects produced by mental processes, we can develop - and then test - hypotheses about what the mental processes must have been ▯ Working Memory: Some initial Observations Working Memory is the memory you use for information that you are actively working on • Holds information in an easily accessible form • Instantly available when you need it • Promoted by several factors: • Working memory size: hypothesized to have a small capacity One way to measure working memory’s capacity is via a span test • In this test, we read to someone a list of say, four items, perhaps four letters (“A D G W”). The person has to report these back, immediately, in sequence. If she succeeds, we try it again with five letters. If she can repeat these back correctly, we try six letters, and so on, until we find a list that the person cannot report back accurately. •Generally, people start making errors with sequences of seven or eight letters ▯ Working Memory: A Proposal • When people make mistakes in this task, they generally substitute one letter for another with a similar sound. Having head “V” they’ll report back “B” ▯ Alan Baddeley and Graham Hitch - proposed a model to explain both this finding and many others as well. Their model starts by stipulating that working memory is not a single entity. •Working memory has several different parts, and so they prefer to speak of a working memory system •At the heart of the system is the central executive - this is the part that runs the show and does the real work. •The executive is helped out by a number of low-level “assistants” They can provide storage, and this function, simple though it is, makes the assistants • extremely useful •Specifically, information that will soon be needed, but isn’t needed right now, can be sent off to the assistants for temporary storage. • One of the most important assistants is the articulatory rehearsal loop • To launch the rehearsal loop, you rely on the process of subvocalization, or silent speech. (This is where you quietly say the numbers to yourself.) • Subvocalization, in turn, produces a representation of these numbers in the phonological buffer (in other words, an auditory image is created in the “inner ear”. This image will fade away after a second or two, but before it does, subvocalization can be used once again to create a new image, sustaining the material in this buffer ▯ EvWhy do people make “sound alike” errors in a span task? • It’s because they’re relying on the rehearsal loop, which involves a mechanism (the “inner • ear” ordinarily used for actual hearing • Example: imagine that we ask people to take the span test while simultaneously saying “tah- tah-tah” over and over, out loud. This concurrent articulation task obviously requires the mechanisms for speech production. Therefore, these mechanisms are not available for other use, including subvocalization. • Span is ordinarily about seven items; with concurrent articulation, it drops by roughly a third to four or five items. • With concurrent articulation and video presentation of the items, sound alike errors are largely eliminated ▯ We can also test people’s memory spends by using complex visual shapes. People are shown these shapes and then must echo the sequence back by drawing what they have just seen. If we choose shapes that are not easily named, then the shapes cannot be rehearsed via the inner voice/inner ▯ar combination. • Concurrent articulation blocks use of the loop but has no effect on someone’s ability to read brief sentences, to do simple logic problems, and so on. (Blocking use of the loop does have an effect when you’re reading more complex sentences or doing harder problems; that’s because these harder tasks require analysis and the storage of interim steps and so require the entire working- memory system - the executive and the assistants ▯ ▯ The Nature of the Working-Memory Evidence • Cognitive Neuroscience - the study of the biological basis for cognitive functioning • Because of specific forms of neurological damage, some individuals have no ability to move these various muscles and so suffer from anorthic - an inability to produce overt speech • Actual muscle movements aren’t needed for subvocalization, because the results are the same without these movements. It seems likely, therefore, that “inner speech” relies on the brain areas responsible for planning and controlling the muscle movements of speech and not on the Observations from neuropsychology, concerned with how various forms of brain dysfunction • influence observed performance • Deaf rely on a different assistant for working memory: they use an “inner hand” (and covert sign language) rather than an “inner voice” (and covert speech) ▯ ▯ ▯ ▯ ▯ ▯ ▯ ▯ ▯ Chapter Two: The Neural Basis for Cognition ▯ Capgras Syndrome: An Initial Example • The disorder can result from various injuries to the brain • Fully able to recognize people in their world - partner, parents, friends - but utterly convinced that these people are not who they appear to be Often a person with Capgras syndrome insists that there are slight differences between • the impostor and the person he has replaced - subtle changes in personality or tiny changes in appearance • Patients suffering from this syndrome have murdered the supposed impostor in an attempt to end the charade and relocate the “genuine” character. • Facial recognition involves two separate systems in the brain, one of which leads to a cognitive appraisal, and the other to a more global emotional appraisal • In this syndrome however, the emotional processing is disrupted, leading to intellectual identification without the familiarity response ▯ Neural Basis for Capgras Syndrome Neuroimaging Techniques - Allow researchers to take high quality, three-dimensional “pictures” of living brains, without in any way disturbing the brains’ owners ▯ One site of damage in Capgras patients is in the temporal lobe • particularly on the right side of the head • this damage probably disrupts circuits involving the amygdala (an almond shaped structure that seems to serve as an “emotional evaluator,” helping an organism to detect stimuli associated with threat or danger • also important for detecting positive stimuli • without the amygdala or if its damaged (people with Capgras syndrome) will not experience the warm sense of feeling good (and safe and secure) when looking at a loved one’s familiar face • People with Capgras syndrome also have brain abnormalities in the frontal lobe, specifically in the right prefrontal cortex • fMRI to find info about this which allows us to track moment-by-moment activity levels in different sites in a living brain • Prefrontal cortex is especially active when a person is engaged in tasks that require planning, or careful analysis • With damage to the frontal lobe, Capgras patients may be less able to keep track of what is real and what is not, what is sensible and what is not • As a result, weird beliefs can emerge unchecked, including delusions that you or I would find utterly bizarre ▯ What Do We Learn From Capgras Syndrome? • Recognition of all stimuli (and not just faces) does involve two separate mechanisms - one that hinges on factual knowledge, and one that’s more “emotional” and tied to the warm sense of familiarity • The damage to the amygdala is probably the reason Capgras patients experience no sense of familiarity when they look at faces they know well • Damage to the prefrontal cortex in turn helps us understand why Capgras patients, when they experience this lack of familiarity, offer such crazy hypotheses about their skewed perception ▯ Capgras syndrome illuminates broader issues • Example: suggests that the amygdala plays a crucial role in supporting the feeling of familiarity • The amygdala also plays a central part in helping people remember the emotional events in their lives • Also plays a role in decision making, especially for decisions that rest on emotional evaluations of one’s options ▯ • Capgras syndrome tells us that this emotional evaluator works in fashion separate from the evaluation of factual information, providing us a way to think about the occasions in which someone’s evaluation of the facts points toward one conclusion, while an emotional evaluation points toward a different conclusion ▯ The Study of the Brain • The human brain weighs between 3 and 4 pounds • Structure is estimated to contain a trillion nerve cells, each of which is connected to 10,000 or so others - roughly 10 million billion connections • Huge number of glial cells • Different parts of the brain perform different jobs ▯ Construction accident caused Phineas Gage to suffer damage in the frontmost part of his brain This damage led to severe personality and emotional problems • •Damage on the left side of the brain, led to disruption of language skills ▯ Hindbrain, Midbrain, Forebrain Divided into three main structure: the hindbrain, the midbrain, and the forebrain ▯ Hindbrain •Sits directly atop the spinal cord and includes several structures crucial for controlling key life functions •Example: Makes sure that the rhythm of heartbeats and the rhythm of breathing are regulated •Essential role in maintaining the body’s overall tone; specifically, the hindbrain helps maintain the body’s posture and balance, and it helps control the brain’s level of alertness • Largest area of the hindbrain is the cerebellum • Main role of this is the coordination of bodily movements and balance Also plays a diverse set of other roles, and damage to this organ can cause problems • in spatial reasoning, in discriminating sounds, and in integrating the input received from various sensory systems ▯ Midbrain •Coordinates movements, including the skilled, precise movements of your eyes as you explore the visual world •Also include circuits that relay auditory information from the ears to the area in the forebrain where this information is processed and interpreted. •Helps to regulate the experience of pain ▯ Forebrain •Most interesting brain region (and in humans is the largest region) Only the outer surface of the brain - the cortex - that is visible in pictures • • Cortex “tree bark” refers to an organ’s surface, and many organs each have their own cortex; whats visible in drawings is the cerebral cortex • Cortex is just a thin covering on the outer surface of the forebrain - 3mm thick • Constitutes 80% of the human brain • Very large sheet of tissue; if stretched out flat, it would cover more than 2 square feet • It is crumpled however and jammed into the limited space inside the skull • The wrinkles, or convolutions that cover the brain’s outer surface ▯ The deepest groove is the longitudinal fissure, running from the front of the brain to the back, which separates the left central hemisphere from the right. Other fissures divide the cortex in each hemisphere into four lobes, and these are named after the bones that cover them - which make up the skull. ▯ • The frontal lobes form the front of the brain - right behind the forehead • The central fissure divides the frontal lobes on each side of the brain from the parietal lobes, the brain’s top most part. • The bottom edge of the frontal lobes is marked by the lateral fissure, and below it are the temporal lobes • At the very back of the brain, connected to the parietal and temporal lobes, are the occipital lobes ▯ Subcortical Structures • Underneath the cortex, are the subcortical parts of the forebrain • The thalamus, acts as a relay station for nearly all the sensory information going to the cortex Directly underneath the thalamus is the hypothalamus, a structure that plays a crucial • role in controlling motivated behaviours such as eating, drinking, and sexual activity • Surrounding the thalamus and hypothalamus is another set of interconnected structures that together form the limbic system •Included here is the amygdala, and close by is the hippocampus, both located underneath the cortex in the temporal lobe •These structures are essential for learning and memory ▯ Lateralization Virtually all parts of the brain come in pairs. ▯ • Cortical and subcortical, the left and right structures in each pair have roughly the same shape and the same pattern of connections to other brain areas. • There are differences in function between the left-side and right-side structures, with the left-hemisphere structure playing a somewhat different role from the corresponding right-hemisphere structure. ▯ • Two halves of the brain work together • This integration is made possible by the commissures, thick bundles of fibres that carry information back and forth between the two hemispheres. • The largest commissure is the corpus callosum ▯ • Language capacities are generally lodged in the left hemisphere, while the right hemisphere seems crucial for a number of tasks involving spatial judgment ▯ • The complex, sophisticated skills we each display (including creativity, intuition, and more) depend on the whole brain •Our hemispheres are not cerebral competitors, each trying to important its style of thinking on the other, instead, the hemisphere pool their specialized capacities to produce a seamlessly integrated single mental self ▯ Data from Neuropsychology Neuropsychology: The study of the brain’s structures and how they relate to brain function •The specialty of clinical neuropsychology seeks to understand the functioning of intact, undamaged brains by careful scrutiny of cases involving brain damage ▯ • A lesion (specific area of damage) in the hippocampus produces memory problems but not language disorders; a lesion in the occipital cortex produces problems in vision but spares the other sensory modalities • Damage to the left side of the frontal lobe, for example, is likely to produce a disruption of language use; damage to the right side of the frontal lobe generally doesn’t have this effect ▯ Data from Neuroimaging Allow us to take precise three-dimensional pictures of the brain ▯ • Computerized Axial Tomography (CT scans) study the brains structure •Rely on x-rays and in essence provide a three dimensional X-ray picture of the brain •Map tells us the shape, size, and position of structures within the brain • Positron emission Tomography (PET Scans) to study the brains activity •Start by introducing a tracer substance such as glucose into the body; the molecules of this tracer have been tagged with a low dose of radioactivity and the scan keeps track of this radioactivity, allowing us to tell which tissues are using more of the glucose and which are using less. •Map tells us what regions are particularly active at any point in time •Magnetic Resonance Imaging (MRI) relies on the magnetic properties of the atoms that make up the brain tissue, and it yields fabulously detailed pictures of the brain •Functional Magnetic Resonance Imaging (fMRI) measures the oxygen content in the blood flowing through each region of the brain; this turns out to be an accurate index of the level of neural activity in that region • Brain’s moment-by-moment activities • The result of PET or fMRI scans are highly variable because the results depend on the task the person is performing ▯ Data from Electrical Recording Electrical recording of the brain’s activity ▯ • The brain contains a trillion nerve cells - neurons - and it is the neurons that do the brains main work • Neurons vary in their shape, size and functioning •Communicate with each other via chemical signals calls neurotransmitters: Once a neuron is “activated,” it releases the transmitter, and this chemical can then activate (or deactivate) other, immediately-adjacent neurons •The adjacent neurons “receive” this chemical signal, and they can send the signal onward to still other neurons ▯ • This process requires two types of communication: •One type is “between neurons” and involves the chemical signals we just describ
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