Cognitive Final
Interactive Activation Model
- A connectionist model of letter and word recognition -Stimulus (letter)-->Feature level-->Letter level-->Word Level
Process Models
- A hypothesis about the specific mental processes that take place when a particular task is performed -Ex. Lexical Decision Task: deciding whether it is a word or non-word (faster RT when actual word or when it is more common and found in mental dictionary more easily)
Movement Facilitates Perception
- Adds complexity to perception - But, also helps us perceive objects in environment more accurately - 2 processing streams in brain: 1) Perceiving Objects-Perception pathway (what)-from visual cortex to temporal lobe 2) locating/taking action toward these objets-Action pathway (where)-from visual to parietal lobe
Functional Modules
- Auditory, visual, touch,smell are all processed in different areas of the brain - Have to combine for a single experience - Visual Cortex is divided into sections that process different things like depth, shape, color, etc.
Neuron
- Basic building block of the nervous system - Moves electrical signals into, out of, and through the brain -Negatively charged
Gross Anatomy of Brain
- Brain is wrapped in a fibrous encasing that protects it - Four Major Lobes 1) Frontal Lobe: receives signals from all of senses and plays an important role in perceptions that involve coordination 2) Temporal Lobe: sound-ear 3) Parietal Lobe: touch, temperature,and pain 4) Occipital Lobe: Grand central station of the brain b/c first stop for things entering the brain; primary receiving area for vision -Corpus Callosom: Connects neurons across two hemispheres which allows communication for function -Folds in brain=gyrus - Convoluted structure b/c over time the surface becomes smoother, but needed to increase the surface area without increasing the volume too much-->folds
"Protoplasmic Kiss"
- Cajal Nobel Prize - Nts are released from Neuron B and then reabsorbed by presynaptic neuron (Neuron A-where they were previously released from)
Principle of Componential Recovery
- Can perceive objects even if portions of geons are obscured -Ex. a flashlight
Neurotransmitters
- Chemicals that move from one neuron to another that change this negative charge to positive - When neurons have positive charge they will fire -Are held inside the terminal button - Absorbed the postsynaptic dendrite of other neuron they are being absorbed by
Metatheory
- Cognition is the coordinated operation of active mental processes within a multi-component memory system
Activation & Inhibition
- Combine to make neural circuits - Create neurons that respond to specific types of stimuli -Inhibition you experience: Mach Bands
Flow Diagrams for Digital Computers
- Computers process information in stages -Input-->Input processor-->Memory unit-->Arithmetic unit--->Output -Donald Broadbent proposed first flow diagram of mind
Hermann Ebbinghaus & Learning Curve
- Considered higher mental processes important -Focus was on forming associations (learning); meaning, imagery, individual differences, intelligence testing -Method: verbal learning -Learning Curve/"Savings Curve": To determine how much info was saved in memory over time * Presented nonsense syllables to be remembered *Savings were much greater for short intervals than for long *Found that there was a lot of forgetting really early (first 2 days) on *But, whatever you remember after 9 hours you will retain for a long time *Sudden drop then flattens out -Showed that memory could be quantified and again made inferences from behavior about functions of the mind
Why Feature Detection is not enough?
- Context biases our perception of the world * Ex. Word Superiority Effect shows that letters in words are recognized better than in isolation * Ex. Multiple Personalities of a blob -Focusing on the bottom-up overlooks many abilities * Ability to still read a paragraph when each word has letters swapped
Nerve Net
- Continuous network and complex pathway for conducting signals uninterrupted - Could see when 19th cent. anatomists applied stains to brain tissue
Selective Attention
- Deliberate voluntary allocation of mental effort or concentration - The ability to attend to one source of info while ignoring/excluding the other ongoing messages
Structural Modules- Brodmann's Cytoarchitectonic Map
- Different areas compared with surrounding tissue - Biological difference in structure important - Different areas with different functions - Organization of functions
Form vs. Meaning Problems
- Form: difficulties in determining relation between words in a sentence - Meaning: wider difficulties in understanding like those experienced in Wernicke's * Evidence that patients w/Broca's aphasia have problem with understanding language * Now don't distinguish b/w production and understanding, but b/w form and meaning
Operant Conditioning
- How behavior is strengthened by the presentation of positive reinforcers like food or social approval (or w/draw of negative reinforcers like shock/social rejection) -Not interested on what's going on inside head, just relationship between stimuli and response
Neuron Doctrine
- Individual cells transmit signals in the nervous system and aren't continuous with other cells -Discovered by Cajal
Cerebral Cortex
- Layer of tissue that covers the brain -Wrinkled covering
Laws of Perceptual Organization
- Mind groups patterns according to these rules
Recognition by Components
- Model of object recognition - Objects are recognized by: 1) Breaking them down into their component parts 2) Determine how the parts interconnect or the "pattern" that they make 3) Look up this pattern of parts in memory 4) Identify an object that matches this pattern **Breaking objects down into geons ** If we perceive just a few geons we can then recognize an object
Neural Code for Memory
- Neural firing assoc. w/experiencing a perception is caused by stimulation of sensory receptors -NF caused by firing in structures that contain info about what happened in past
Bottom-up Processing (behavioral)
- Neurons fire to individual features of an object suggests that our perception of object is created by combining info provided by firing of many feature detectors -Recognition by Components
Neural Circuits
- Neurons form connections to specific neurons to form these
Neurons and Gestalt Grouping
- Neurons respond maximally to displays that reflect 1) similarity 2) Good continuation *More about context than random placement
Receptors
- Neurons that pick up info from the environment like those in skin, eye, and ear - Similar to brain neurons b/c have cell body & axon - But, have specialized receptors that pick up info from the environment
Cocktail Party Effect
- Person is selectively listening to one message among many - But, hears his/her name or some distinctive messages like "Fire" that's not being attended - Happens b/c they're taking meaning of words into account **Evidence against Broadbent's theory that only one message or attended message based on physical characteristics * But, shows that info from other message hadn't been filtered out & analyzed based on MEANING
Colin Cherry's Auditory Ex.
- Presented participants with two messages at same time , one to each ear -Told to focus attention on one (attended message) and ignore the other one (unattended message)
Contralaterality of Function
- Receptive and control centers for one side of body are controlled by the opposite hemisphere of the brain - Discovered through split-brain studies: sever corpus callosum to remedy epileptic seizures and found that the "cross talk" between hemispheres was lost
Specificity Coding
- Representation of a specific stimulus like a person's face by firing of a very specifically tuned neurons that are specialized to respond just to that face
What are the components of objects?
- Simple 3-d geometric forms called geons -36 geons combine to make all 3-d objects
Distributed Processing
- Specific functions are processed by many different areas in the brain -Research that multiple areas in every lobe of brain are involved in strong memories for facts/events and remembering them later b/c elicits visual, auditory, smell, and taste perceptions -Different types of memory activate different and sometimes overlapping areas of brain
Hemisphere Specialization
- Speech centers; Verbal/language/vocab=left-hemisphere - Visual Area/faces/music/spatial/geometry=right-hemisphere * Left-handed people are less homogenous in their brain organization * Right-handed people tend to have more lateral function - Hemispheres aren't functionally symmetric - Ex. Face processing dominated by RH, controls left-visual field so choose face with younger half on left more often than right
Bottom-Up Processing (physiological)
- Stimulation of receptors - Feature detectors response is 1st step in brain's response to objects by responding to simple shapes like lines and bars -
Neural Code
- The way these patterns of neural firing represent environmental stimuli
Gestalt Approach to Info-Processing
- The whole is different from the sum of the parts -Perception is the result of perceptual organization - Sensation isn't the sum of individual sensations, but the patterns created in the visual world -Perception is the result of adding some sort of interpretation to the features present
Synapse
- Tiny gap between neurons - Signals from presynaptic neuron to postsynaptic neuron and must cross the gap -Crosses gap by complicated electro-chemical process
Axon or nerve fiber
- Transmits signals to other neurons -Neuron has receiving/transmitting end and its role is to transmit signals
B.F. Skinner
- Unconcerned with thought, mind, and consciousness - Another behaviorist - Method: Operant conditioning - Ex. PRoject Pigeon (trained pigeons to peck a particular target)
Action Potential
- When neuron has positive charge and ready to fire -Nerve impulse from single neurons - Each AP travels all the way down the axon w/out changing its size, so ideal for sending signals over a distance
Computational Modeling
- human info processing similar to the way that computers work - Computer operations may give insight into how humans work -Creating computer programs that mimic human behavior may give insight into mechanisms of behavior
Rationalists
-"Active Mind" -Innate mental structures, principles, operations, abilities apply meaning to sensory information -Consider more than content of mind -Deduction analysis, argument, and intuition lead to truths not available by senses alone
Empiricists
-"passive mind" -Senses constitute basis of knowledge -Nothing is innate -Mental events can be explained by a few mechanistic principles or laws
Neural Transmission
-1)All or none: no gain control -2)Unidirectional: dendrites to terminal buttons -3) Signals propagate by convergence and divergence
Localization of Perception
-4 major lobes are primary receiving areas b/c 1st areas of cerebral cortex to receive signals from each of these senses
Franciscus Donders
-Choice Response Task to study decision-making -Did this by measuring reaction time or how long it takes to respond to the presentation of a stimulus ( Time between presentation of stimulus and behavioral response) -One of 1st cog psych exs. and shows that mental responses (perceiving light-->behavioral response of pushing button) can't be measured directly, but must be inferred from behavior
Cognitive Control
-Controlled Task: cocktail party effect - Uncontrolled Task: Stroop Task
The Cognitive Revolution
-Empirical challenges to behaviorism combined with a political and scientific atmosphere that rekindled interest in the human as an information processor leading to birth of Cognitive Psychology -MIT Symposium: Newell&Simon compared humans to computers -Chomsky discusses language as inherited rule-governed system -Miller presented work on STM
Perception
-Experience resulting from stimulation of senses -Involves a dynamic process -Gateway to all other cognitions -Occurs in conjunction with action
Wilhem Wundt
-Focus was on conscious processes and immediate experiences (today's sensation, perception, and attention) -Analytic Introspection: *Build a periodic table of perception and have people tell them what they're feeling/experiencing *Ex. with clock pendulum-shows that people have trouble telling where it was when bell rings have trouble b/c paying attention to 2 things at once
Choice Reaction Time Task
-Have to press J key if left light came on and K key if right light goes on -Choice Reaction Time: longer than simple reaction time b/c of the additional time it takes to make the decision and that difference in RT b/w simple and choice would indicate how long it took to make the decision (1/10th of second)
Figure-Ground Segregation
-Having to determine what part of environment is the figure so that it "stands out" from the background -Factors that determine which area is figure: 1) Elements in lower parts of displays 2) Units that are symmetrical 3) Elements that are small 4) Units that are oriented vertically 5) Elements that have meaning
Algorithm vs. Heuristic
-Heuristic: rule of thumb that provides best-guess solution to problem *Faster than algorithm so perceptual system is designed to operate in way that sometimes produces errors-survival instinct -Algorithm: procedure that's guaranteed to solve problem
Neurons and Feature Detection
-Individual Neurons can respond maximally to features like size, orientation, and motion
Feed-Forward and Feed-Back Processing
-Interaction between top-down and bottom-up processing -Ex. Word superiority effect shows that if given a stimulus (letter) that appears in a word, faster activation b/c able to use prior knowledge - Integrating top-down info back down
Grandmother Cell
-Jerry Lettvin -Neuron that responds only to a specific stimulus Problems with this: 1) There are too many diff. faces and other objects in environment to assign specific neurons to each one 2) There are neurons that respond only to specific types of stimuli, even these neurons respond to a number of diff. faces *Hasn't been accepted by researchers -Solution: certain face is represented by firing of a group of neurons, but with different patterns -Distributed coding: specific face is distributed across a # of neurons w/advantage that firing just a few neurons signal a large # of stimuli
Channel Capacity
-LIke a telephone wire, humans are limited-capacity information processors
Characteristics of Cognitive Psychology
-Mental processes exist - Mental processes can be studied scientifically - Humans are active information processors
Localization of Function
-Neurons serving different functions transmit signals to different areas of the brain which leads to different qualities for different types of senses -Demonstrated through fMRIs that identify specific areas of brain responsible for certain functions (module: specialized for a specific function) - Prosopagnosia: inability to recognize faces cause by damage to certain area of temporal lobe
Are Gestalt Principles really laws?
-No, they help us overcome challenges to object perception, but don't make strong enough predictions to be considered laws - Are Heuristics or "best guess rules"
Feature Detection Theories
-Object recognition depends on identifying a rudimentary set of features -Neurophysiology: receptive fields in visual cortex
Localization for Language
-Paul Broca: * Area in frontal lobe specialized for producing language * Patients who suffered from strokes had speech that was slow/labored ( Damage to Broca's Area-Broca's Aphasia) Carl Wernicke: * Patients who had damage to temporal lobe * Their speech was fluently/grammatically correct, but tended to be incoherent *Wernicke's aphasia - Specific language functions localized in specific brain areas -But, at same time language processing is distributed over large area of brain
Philosophy vs. Physiology
-Philosophy: *Understanding the nature of the world and thoughts through reasoning -Physiology: *the scientific study of life sustaining functions of living matter
Simple Reaction Time Task
-Presentation of a light and then have to press key when it comes on
Top-Down Processing
-Processing that begins with a person's prior knowledge or expectations -Ex. Multiple Personalities of a blob * Blob that has same geons in all of the pics, will be perceived as diff. objects b/c our knowledge of the what's likely to be found in certain context -Feedback Signals: * Travel down from higher centers to influence incoming signals EVIDENCE: -Scene Schemas: observer's knowledge about what's contained in typical scenes * People look longer at things that seem out of place meaning that attention affected by knowledge of what's usually found in scene -Person's eye mov'ts are determined mostly by task
Feature Detectors
-Respond to features that make up objects could be involved -Evidence that each of 1,000s of neurons that fire when we look at an object fire to different features of object
Skinner vs. Chomsky (Language Acquisition)
-Skinner: Language is learned through reinforcement and conditioning *Ex. praise from parents leads them to use words -Chomsky: Language is an innate ability supported by flexible cognitive mechanisms * Ex. But, kids will say things that were never rewarded (like I hitted the ball or I hate you)
Neurons & Figure Grounded Segregation
-Studies of monkey cortex show that response to area that is figure, but none to ground -See exactly same thing, but different depending on whether it appears in background or not -Shows Contextual Modulation
Tolman's Maze Experiments
-Suggest cognitive maps: a conception of the maze's layout -Rats put in maze to find food -When put in maze similar to how they ran first one, invent new route to get to same place as food would have been
Theory of Unconscious Inference (Speech Segmentation & Likelihood Principle )
-Theory of Unconscious Inference: some of our perceptions are the result of unconscious assumptions that we make about the environment -Speech Segmentation: ability to perceive sound of language as meaningful words, knowing when one word ends and next one begins * Two people can heard same sound stimuli, but experience different perceptions -Likelihood Principle: we perceive object that's most likely to have caused pattern of stimuli we've recovered
Intelligence of Perception
-There is intelligence to object processing shown through our use of top-down processing or previous knowledge
Modularity vs. Distribution
-There's modularity to perception, but perception is also diffuse
Visual Processing
-Top-down Processing: expectations and existing knowledge influence perception - Bottom-down Processing: Perception based on incoming data
John B. Watson
-Unconcerned with thought, mind, and consciousness - Behaviorist - Focus was on observable and quantifiable behavior -Method: relate observable behavior to observable stimulus conditions (classical conditioning) with no difference between humans and animals (arrive in world with blank slate) -Ex. Little Albert Experiment: classical conditioning-pairing one stimulus (loud noise) with a neutral stimulus (rat) caused change in response to neutral stimulus -inspired by Ivan Pavlov *Didn't matter what was going on inside Albert's head, behavior important
Modules
-Visual Cortex composed of several diff. areas specializing in diff. processes - 4 types: faces, places, bodies, and things
Resting Potential
-When neuron has negative charge -
Challenge of Object Perception
1) -The stimulus on the receptors is ambiguous -There's the inverse projection problem:image on the retina can be caused by an infinite number of objects 2) Objects Can be Hidden - Occlusions are common in the environment 3) Objects look different from different viewpoints - Viewpoint invariance: ability to recognize an object regardless of the viewpoint 4) Objects need to be separated -Where does one object end and the other one begin? 5) Light changes can be ambiguous - Are changes in lightness and darkness due to the properties of the objects or illumination (like the sun making half of the wall look lighter) 6) Size and distance are confounded
Evidence for Recognition by Components
1) Accidental Properties 2) The principle of Componential Recovery
Neuropsychological Methods
1) Animal Studies: Single cell recording * Record activity of single cell while animal performs task to look at function of one neuron 2) Animal Studies:Lesions * Cause damage to gross areas of the brain * Observe behavioral ability given neurological deficit 3) Human Studies: Lesion * Observe behavioral ability given neuro deficit 4) Transcranial Magnetic Stimulation * Apply very strong and direct magnetic field to a region of cortex * Magnetic field stimulates neurons to fire, interferes with normal functioning and creates "virtual lesions" * Disrupt functioning in particular part of brain and study effect of this on person's behavior 5) Event Related Potentials * Electrical activity recorded with sensors on scalp * Activity recorded in response to a stimulus over multiple presentations * Each record averaged to eliminate "noise" * Result is an event related potential, electrical activity associated with the stimulus * Spatial resolution isn't very good b/c looking at surface of cortex 5) Functional Magnetic Resonance Imaging (fMRI) * Indirect measure of neural events * Measurement of cerebral blood flow * B/c oxygenated and de-oxygenated blood have different magnetic properties * Can see deeper areas of brain (spatial resolution) * But, not good temporal resolution, can see precisely when it's happening * Preferred over PET b/c more accurate and is less invasive
Neurodeficits in Object Perception
1) Apperceptive Agnosia - Processing deficit in feature - Right Parietal Lob damage - Can't copy objects or recognize objects 2) Associative Agnosia -Processing deficit in global - Left Parietal lobe damage - Can draw model, but can't tell what it is
Major Themes in Cognitive Psychology
1) Cognitive control 2) Data-Driven vs. Conceptually Driven Processing 3) Automaticity and Awareness 4) Representation 5) Channel Capacity 6) Brain
Problems with Behaviorism
1) Conditioning Doesn't explain all animal behavior *Different behaviors couldn't be conditioned in animals (Breland's rooting pigs) and animals form unpredicted associations (Garcia's nauseated rats) 2) Conditioning doesn't explain all human behavior *Research started to suggest that psychology needed to consider internal mechanisms 3) Practical and applied problems were forgotten *The World Wars changed the focus of psychology *Concepts of attention and vigilance returned * Decision making viewed as necessary part of performance 4) The Computer Model *Computers take in info, perform internal operations on that input, and return some output *Processes used by computer to create output NOT observable, but exist
Properties of Geons
1) Discriminability: 2) View-Invariant Properties
Intelligence of Object Processing
1) Intelligence comes from natural selection with the brain evolving to process information -Shaped processors to handle the kind of info we normally confront in the environment -Oblique effect: people are more sensitive to horizontal and verticals ovr obliques w/more neurons responding to these b/c more cortical space 2) Experience-dependent plasticity - Our direct experiences help tune the brain to handle visual info accurately -Neurons respond best to the type of info to which person is exposed -FFA in temporal lob has many neurons that respond best to faces/other complex objects which are est. by experience w/objects -Ex. Grevals: After learning about these foreign objects are able to determine small details that distinguish what were previously undistinguishable
Gestalt Laws of Perceptual Organization
1) Law of Simplicity 2) Law of Similarity 3) Law of Good continuation *Lines tend to be seen as following smoothest path *Overlap Effect: even when overlapping not seen as separate pieces 4) Law of Proximity 5) Common Region 6) Law of Familiarity 7) Synchrony 8) Law of Common Fate 9) Apparent Motion and Occlusion 10) Apparent Motion and Physical Boundaries
What & Where Pathways
1) Monkey Study -Object Discrimination Problem: What pathway ( temporal lobe) * Have to determine what the object was -Landmark Discrimination Problem: Where pathway (parietal lobe) * Had to determine where food was 2) Patient D.F. -Ventral pathway damage 3) Rod and Frame Illusion
Steps in Process of Making Neuron Negative-Positive
1) Neuron B has negative charge (resting potential) 2) Electrical signal in Neuron A causes release of neurotransmitters from terminal button into synapse 3) Neurotransmitters are absorbed by dendrite of Neuron B 4) Electrical signal is transferred with Neuron B absorbing the Nts 5) Neuron B is now positive and fires (action potential)
3 Levels of Analysis in brain's processing of objects
1) Neurons: certain neurons specialized for particular kinds of processing 2) Modules: Certain areas are specialized to serve specific functions 3) Streams: Certain sequences of interconnected structures serve specific functions
Perceptual Heuristics
1) Occlusion Heuristic 2) Light From Above
Modern Times-How do we measure information processing?
1) Reaction Time * Time elapsed between stimulus and response stimulus * Experimenter knows inputs, but how long to get outputs *Switching b/w two tasks takes more time b/c have to think about one or the other 2) Accuracy * How many/what kind of errors do people make? * Remember 1st and last part of a list best-memory not random 3) Verbal Report *Description by subject of how task is completed * Used for tasks that RT or accuracy aren't helpful * Ex. Complex problem solving like in chess 4) Non-Explicit Measures ( Eye-Tracking) *Real-time processing indicator that doesn't require explicit awareness * B/c not always aware of what your eye movements and way you say you did and what you actually did don't always match up 5) Brain Imaging * Measures brain activity while you're performing a task
Evidence for Feature Detection
1) Visual Search Tasks: * Finding a particular target letter is more difficult when the letters have more similar features * Ex. Discriminating an R in the middle of Ps and Qs is harder than finding an O in the middle of Vs
Determining the Object
2) Compare structural descriptions of geons to similar patterns stored in memory 2) Object identified as the instance in memory that's most similar to the perceived object
Dendrites
Branch out from cell body to receive signals from other neurons
Cell Body
Contains mechanisms to keep cell alive
Determining the Connections b/w Geons
Determine where and how geons intersect
Dissociations (Single and Double Dissociations)
Dissociations: Situations where one function is absent while another is present -Single Dissociation: studied in one person -Double Dissociation: requires 2 people
Determining the Geons
Locate the edges to determine those that have the same relationship regardless of viewing orientation
Intensity of Stimulus=
Rate of firing of neuron Ex. more pressure on the skin leads neurons in touch system to fire more rapidly and increases the pressure feeling
