PSY 2400- LEC 1, 2, 3 - Lecture notes 1-3 PDF

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Lectures 1-3...

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PSY 2400: LEC 1, 2, 3, 4, 5 Module 1: Methods and Cognitive Neuroscience (Ch. 1,2)

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Cognitive Psychologist: Empirical Approach Develop Theory: Words are stored by familiarity Make Predictions: Familiar words will be recognized more quickly then unfamiliar words Test Predictions: Time how quickly people read familiar and unfamiliar words. Ideas that cannot be tested have no value in experimental science Experimental Paradigms in Cognitive Psychology Standard methods for investigating how humans process information’s Independent variable- The variable that is manipulated by the experimenter. Does exercise influence how well people can remember the details of a story. Dependent variable- measurements made by the experimenter (in cognition research, almost always process speed, processing accuracy or both) Reaction Time (RT) captures processing speed (units are usually always in milliseconds). Percent Correct captures processing accuracy (units might be” percentage of items remembered correctly) Independent- variables manipulated Dependent- measurements made by the experimenter. Stimulus Display- What the participants sees or hears (timing, quality, number of targets, number of distractors, familiarity, etc) Task- Ordinary or extraordinary? Transparent? Easy or difficult? Dose the DV fit? Standard in literature?

Incredibly, F. C. Donders was an ophthalmologist who dabbled in psychology. He was one of the first people who attempted to make inferences about how people thinking by examining how quickly they responded to target stimuli. The subtraction method was hugely influential for Cognitive Psychology. Here’s how it worked. Donders’ goal was to find the duration of mental events for very simple tasks. His subtraction method relied on three assumptions:

1. Mental processing takes time. 2. The time needed to respond to a visual or auditory stimulus is equal to the sum of all the times needed to perform component mental events or stages.

3. Component mental events (aka “stages”) could be inserted or deleted from the sequence without affecting the performance of other stages. This is known as the assumption of pure insertion, and was highly controversial.

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The Basic Tenets of the Information Processing Approach Information is represented and there are mental processes that operate on it. Tasks can be decomposed into component mental events. Mental events take time. We can use experimental methods to discover what these events are and how long they take.

Why did introspection die??? 1. Some tasks are just too simple to produce reportable images and thoughts. For example, if you were asked to press a button, what could you tell me about that experience? Not very much. A very short experiment indeed. 2. There was disagreement between researchers about how to “train” subjects. Aha… subjects needed to be trained to provide their introspections. This is problematic because it suggests that the experimenters could influence the content of the introspection (the outcome of the experiment). 3. The most devastating problem though was that it was nearly impossible to replicate results using introspection. This means that if Scientist A in Vancouver and Scientist B in Montreal ran exactly the same experiment with different people, they would get different results. Remember, if your goal is to find a law, then everybody should report the same feelings and thoughts while doing the task.

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**** Example Test Question Design a one factor experiment- Experiment with only one variable IS LEARNING AFFECTED BY CAFFEINE? In studying whether or not learning is affected by Caffeine, I would have the coffee being the independent variable as the experimental group would receive it and not the control, I would have people learn something with coffee and without and then see their ability learn and its speed in milliseconds which would be my dependent variable.

USING LESION METHOD: In Determining Brain Behavior Relationships Localization: Discovering the brain location that supports a particular cognitive process or function. How can we link brain and behaviour: The lesion method works because if a brain area is associated with cognitive function and that section is destroyed that function should be affected. LESION METHODs

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Identify damaged brain areas. Use carefully designed cognitive tests to describe lost mental functions.

Lesion Method Step 1. Identify Damages with scans 1. CAT scan (x ray tech- brightness reflects density) (BONE. Blood. Brain. CSF) 2. MRI scan (magnet makes H atoms spin and comp translated info to 3D image) Lesion Method Step 2. Cognitive Testing  Choice depends on location of lesion and goal of researcher.  EG. PATIENT DF – Studied by David Milner and Mel Goodale. (she could not remember faces or anything)

USING FUNCTIONAL IMAGING: In Determining Brain Behavior Relationships

Progress in cognitive neuroscience depends on our ability to make connections between brain locations and cognitive skills like perception, memory and decision making. Learning brain anatomy is an important part of this process and you are going to learn the basics here. Below you will find labeled brain drawings. I want you to memories all the parts of the brain that are labeled in these diagrams. In this first picture, we're looking at the brain as if we have (1) split the brain into left and right halves, and (2) we have opened the brain like a book and we're looking at the page on the left . The front of the brain is on the left and the back is on the right. The brain has 3 major parts: 1. The Brain Stem – medulla, pons, midbrain, thalamus and hypothalamus - involved in the regulation of bodily functions. 2. The Cerebellum – plays an important role in controlling movements and keeping track of time. 3. The Cerebrum – this is what we usually think of when we think about the brain. This includes the cerebral cortex and two systems of nuclei called the basal ganglia (important for controlling movements) and the limbic system (important for regulating emotions).

HM changed how we think about the organization of memory. His pattern of memory errors demonstrated to us that storing new material into long term memory is not necessarily dependent on short-term memory (his short-term memory was OK).

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Cognitive psychologists now distinguish between explicit memory and implicit memory. Explicit Memory – our memory for autobiographical events (events that happen in our everyday lives and semantic material (information we learn in school). Implicit Memory – our memory for procedures, rules, and motor skills

Module 2: Perception & Attention (Ch. 3,4)

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Perception and Recognition Perception is FAST Perception is HARD, computers can do math, play chess, walk but they can’t see like humans.

Terminology: Distal Stimulus (physical) Proximal Stimulus (sensations. Physiological processes)Percept (perceptions)

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Direct perceptions Problem for Gibson: Recognition is “viewpoint invariance” Indirect or Constructive Perception Assumption – The world is rich but the proximal stimulus is poor. Perception = Sensory information + past experience in the world.

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The Inverse Projection Problem One source of ambiguity is the inverse projection problem. This problem arises from the fact that the three-dimensional objects that surround us are represented on our flat two-dimensional retinas. The ambiguity that this situation induces is best illustrated by the Necker Cube: The brain makes assumptions about how the world should look based on what we know from experience (top-down influences). Assumption 1: Follow the likelihood principle (von Helmholtz) The likelihood principle just says - choose the interpretation that has worked most often in the past. Take a look at the following image. Assumption 2: Assume a Frame of Reference Consistent with Gravity. Why do we have so many vertical edges? Well, because of gravity. We fight gravity by stacking things on top of one another. This produces a lot of vertical edges. Our visual system "knows" this (i.e. has it stored in memory) and uses it to disambiguate stimuli Assumption 2B: Assume a frame of reference consistent with gravity, But... if there's a more local frame, use that.

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Assumption 3: Assume surfaces are uniformly coloured (and that colour/shading variation is due to differences in depth). 

Assumption 4: Light comes from overhead (i.e. from the sun :). 

Assumption 5: Objects continue to exist behind occluders. 

Assumption 6: Resolve ambiguities by using what you KNOW (your past experiences, aka your memory)! 

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Sensory Memory Attention is not limited because perception is limited. Perception actually works quite well and takes in all the information that is presented to us (but more that we

can typically handle). This information is initially stored in Sensory Memory. Sensory memory is a high capacity - it holds a lot of stuff - but short 

duration - it doesn't hold that stuff for very long - store of information captured by our sensory systems. Sensory memory for visual information is called Iconic Memory and sensory memory for hearing information is called Echoic Memory. Both types of sensory

memory work in the same way.

Sperling's Partial Report Task 

How do we know that sensory memory has a large capacity and short duration? Well, because of experiments performed by legendary cognitive psychologist, George Sperling. Sperling was curious about how much information people could take in at once. He would show displays like this:

Attention: Selective attention refers to our ability (which is not absolute) to choose which of the many things or locations around us we should attend to – that is what we should focus our informationgathering power upon, and respond to. This ability is not absolute, because sometimes we don’t have a choice – some things force themselves upon our attention. Fire alarms, for example, compel our attention because they are loud. They are designed to be impossible to ignore. (Intensity in general – a bright light, an intense pain, a loud noise, a heavy weight dropped on your toe – is difficult to ignore). But much of the time, we actively, deliberately select what we attend to. Divided attention refers to our ability to allocate part of our attention to each of several different things. When we do this, is there any cost, or are we as efficient at identifying and responding to a stimulus when dividing our attention as when we select that stimulus for exclusive attention? Sustained attention refers to our ability to focus our attention on one target for an extended period of time even though the world around us may be bustling and full of change. This is how most of you defined attention in our first Discussion. In everyday language, sustained attention refers to your ability to concentrate. Sustained attention became a very important topic during World War Two. Among other tasks, psychologists were asked to study radar operators to determine how their performance changed with time when they attempted to sustain their attention on a radar screen for long periods. (We covered this in Module 1).

Does attention select information early or late?

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Broadbent was one of the first researchers to propose that selection happens early. According to Broadbent's Filter Theory attention selects some information for further perceptual processing based on very simple, physical properties (like how bright it is, how loud it is, how high or low pitch it is) and that only the selected information is perceived and reaches awareness. All other information is discarded - it's as if it never existed.

Attenuation Theory is an intermediate-selection model. Just like Filter Model, the attended message is separated early (before perception) based on physical characteristics. Late Selection According to late selection models of attention, information is selected for further processing after its meaning has been determined (i.e. after it has been perceived)....