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Cognitive Psychology -- Neisser
refers to all processes by which the sensory input is transformed, reduced, elaborated, stored, recovered, and used
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Cognitive Psychology -- Solso
the scientific study of the thinking mind
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Cognitive questions about the mind
- What is it?
- What are the contents?
- Where did those contents come from?
- How does the mind interact with the world?
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Plato's Idea
- Information from the senses is incomplete/imperfect (cave analogy)
- Most knowledge exists innately (accessed by rational thought , may need appropriate cues)
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Descartes Idea
- The one thing that can be known for sure is that we are capable of thinking
- Ideas and sensations are real, thus the world likely exists
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Rationalism
- Emphasized ideas as the product of logical reasoning
- Contents of the mind are endogenous
- Mistrusts senses as source of valid information
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Empiricism
Contents of the mind based on sensory input, observation
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Empiricist: Contents of the Mind
- Tabula Rasa
- First input: sensations
- Subsequent ideas through association of sensations and ideas
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Psychophysicists
- Ernst Weber
- Gustave Fechner
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Psychophysicists - primary question
- How does sensation become an idea
- Absolute/Difference thresholds
- Remains a sub-discipline of cognitive psychology
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Wilhelm Wundt
- Along with the introspectionist
- Investigated consciousness by direct inspection
- Consciousness the object of focus
- Either its parts or its purpose and action
- What are the contents and operations of the mind
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Gestalt Psychology
- Phenomenological experience is not solely a product of bottom up activity
- whole perception: sum (parts, relationships among them) - the importance of stimulus context
- Early examples included the "Gestalt Laws of Perception"
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Behaviorism
- Emphasized empirical data
- behavior, not introspection
- Early framework: S-R
- Later approaches incorporated S-O-R
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Tolman
- Behaviorism
- Latent learning (rats learned a maze without direct reward in the goal box)
- Cognitive maps (rats learned context, not just S-R associations)
- A forerunner of investigations of cognition
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Hull
- Mathematical theory
- Modeled state, effect of organism, set of the mind
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Modern Cognitive Psychology
- Developed in 1950s and 1960s
- Strict behaviorism couldn't address interesting questions about mental operations
- "New Look" - attempted to explain psychodynamic phenomena in behaviorist paradigm
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Information Processing
- The central concept in cognitive psychology
- Based on computer metaphor
- Classic version: cognition occurs as a sequential series of events in which info is encoded,
- computations occur, and results used to influence behavior
- Modern version: parallel processing is emphasized
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Sensory Store
- Representation of sensory information
- Held for short duration (<500 ms for vision)
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Pattern Recognition
- Combination of sensory elements into an object
- activates all or part of a previously stored representation
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Filters, Selection
- Attention: filter only allowing a subset of info for additional processing
- Selection: a post-identification filter
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Response Selection
- The goal of info processing is the adaptive control of behavior
- Output allows the selection of the next behavior (action, speech, thought).
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Mental Chronometry: central concept,
- A method for investigating IP
- Central concept: mental processing takes time
- Assumes that each sequential processing step takes time
- Adding operations takes additional time
- Increasing the difficulty takes additional time
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Subtraction Method
- Donders
- By subtraction, we can calculate the time taken in specific operations
- Time for signal to travel from ankle to shoulder level in the spinal cord
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Neuropsychology
usually refers to a clinical focus, specialization
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- Brain cells
- Consist of: soma, dendrites (input), and axons (output)
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Glia
- Support cells
- 10x more glial cells than neurons
- Provide nutritive and structural support
- produce myelin
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Myelin
- Insulation for axons
- made from lipids and appears white
- nerve fibers are white matter, cell bodies are gray matter
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How do neurons communicate?
Electrical Signals --> Axon --> Synapse --> Action Potential
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Electrical Signal Role in Communication
- Neuron have a voltage
- 70 mV more negative inside than outside
- Electricity travel across dendrite and move in all direction
- Get smaller the further away they are from the source
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Axon Role in Communication
- Special molecules produce the action potential
- electrical signal that travels in one direction
- always the same size
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Synapse Role in Communication
- At the end of axon
- Terminal button releases chemical neurotransmitters
- drift across synapse
- received by molecules on dendrite
- bind to specific molecules like a key in a lock
- NT reception produces AP in receiving neuron
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How do neurons process info?
- Receive input at thousands of junctions
- Combination of synaptic activity determines whether a neuron will or won't produce an AP
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What is the brain?
Neurophysiology and Neuranatomic definition
- NP: the material and efficient cause
- NA: the formal cause (structure and morphology)
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Neocortex
The layer of cells on the surface of the forebrain
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Frontal, Parietal, Temporal, Occipital
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Gyri and Sulci
The hills and valleys on the brain surface
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Important Sulci
- Interhemispheric Fissure
- Central sulcus
- Sylvian Fissure
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Sensory Areas: what and where
- Auditory - Temporal Lobe
- Visual - Occipital Lobe
- somatosensory - Parietal Lobe, behind the central sulcus
- Motor cortex - Frontal Lobe, in front of the central sulcus
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Bell-Magendie Law
- Motor cortex is in the front
- Sensory cortices are in the back
- Motor is ventral, sensory is dorsal
- Same throughout the nervous system
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Corpus Callosum
a fiber tract connecting left and right hemispheres
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Calcarine fissure
Primary Visual cortes
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Thalamus
- Found in the center of the brain
- Sits atop the spinal cord/brainstem
- Sensory/motor relay between cortex and other areas
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Cerebellum
- Part of the motor control system
- PET and fMRI studies indicate it may be important for cognitive function, as well
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Hypothalamus
- Part of the 'limbic system'
- Important for motivation
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Basal Ganglia
- A set of structures deep within the forebrain
- Motor control
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Hippocampus
- In the temporal lobe
- Important for the formation of memory
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Reticular Activating System
- Arousal
- Sleep /wake cycles
- But also general alertness
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Pros for Localization of Cognitive Function
- Phrenology
- Language localization: Broca and Wernicke
- Motor functions: Fritsch & Hitzig
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Cons for Localization of Cognitive Function
- Flourens
- Lashley
- Mass Action
- Equipotentiality
- Hebb
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Flourens
Removed parts of dog brain and did not observe the changes predicted by phrenologists
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Lashley
Had rats learn a complex maze following removal of parts of cortex - looking for the engram (memory trace)
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Mass Action
- Deficit depended upon the amount of cortex removed
- Specific location of the lesion was not important
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Equipotentiality
- Each segment of cortex is capable of functioning like any other
- Differentiation is the result of experience, not intrinsic qualities
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Hebb
- Suggested that memory is a function of large parts of cortex
- The engram is a network of cells that re-wire themselves
- Memory is a function of a mass of cells
- A memory is spread across a network of cells
- A given cell may participate in many memory networks
- Cell Assemblies
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Current opinion of Cognitive Localization
- Many functions can be localized (sensory and language)
- Distributed networks control many functions (Perception, ID, Language, Attention)
- Within a given area, mass action and equipotentiality are valid
- Memory (Agnosia with lesions of ITG
- Perceptual encoding
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Lesions
- Oldest method for studying brain functions
- Problem: removal does NOT mean that the area was the 'center' of a particular function
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Event-related Potentials
- Nerve cells produce small electrical fields
- The sum of these fields is the EEG
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EEG
- EEG may be time locked
- Random fluctuations average out over trials
- producing ERP
- Positive voltage peak at about 300 ms is called P300
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ERP PROs and CONs
- ERPs have excellent temporal resolution
- ERPs have poor spatial resolution
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CT Scans
- An X-ray image of the brain assembled from multiple individual images
- Cons: Poor spatial resolution, doesn't show function well
- Pros: cost effective for diagnosing strokes, tumors, etc.
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Positron Emission Tomography (PET)
- Nerve cells need a lot of oxygen and glucose to function
- radioactive oxygen or glucose is injected and when atom decay they emit rays
- detectors compute location of decay by timing rays
- Use subtraction method to compare multiple conditions
- Pros: decent spatial resolution, shows functional changes
- Cons: high cost, spatial resolution still not great, low temporal resolution (30s)
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fMRI: how it works and pros
- Pros: excellent spatial resolution, decent temporal resolution
- Large magnet causes alignment of molecules
- Second magnetic field is applied to cause some atoms/molecules to shift fields by 90 degrees
- scanner measures change in magnetic field
- different atoms/molecules/ return at different rates
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MRI
- Computer uses field changes to construct a picture of the densities of different atoms/molecules
- Specifically mesures changes in oxygenated blood cells
- specifically de-oxygenated hemoglobin
- where is the brain using the most oxygen
- BOLD-blood oxygenation level dependent image
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Sensory System Structure
- Receptor cells - location of transduction
- Via thalamus
- Cortical project area
- mapping of receptor organ
- environment in represented in contralateral
- Primary cortex projects to secondary, association areas
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Vision:
Receptor organ
Receptor cells
To thalamus
Where in thalamus
Coritcal Projection
- Receptor organ: Retina
- Receptor cells: Photoreceptors --> tranduce photons
- To thalamus: through RGC (retinal ganglion cell axons) in optic nerve
- Where in thalamus: Lateral Geniculate Nucleus (LGN)
- Coritcal Projection
: V1, secondary corticies (dorsal: where and ventral: what paths)
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The Eye: Retina, Fovea, Blind Spot
- Retina: Network of neurons on back wall of eyeball
- Cones: central
- Rods: peripheral
- Fovea: (only cones)
- Blind spot: ganglion cell axons exit, blood vessels access eyeball
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Retinotopic mapping
- Visual field centered at gaze fixation
- Each retina is mapped across V1
- left/right of gaze is processed in contralateral hemisphere
- above/below mapped around calcarine fissure
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Forms Perception
- Figure- Ground Perception
- Proximity
- Similarity
- Continuation
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Gestalt Principles of Perception
- Figure-Ground
- Proximity: reduction of horizontal differences = see as series of rows, reductions of vertical differences = see as column
- Similarity: if see patch of color tend to think of as one whole shape or that they belong together
- Continuation: if edge continues uninterrupted see as one object
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Sinusoidal Visual Perception
Define sine wave and properties of complex wave
- Sine wave:Based on how quickly object reflects/absorbs light
- Complex wave
- Properties:
- Spatial frequency: Cells in V1 are sensitive to different levels of spatial frequency
- Phase: distinguishes different stimuli based on what phase its in
- Contrast: amplitude of wave determines contrast
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Importance of sinusoidal gratings
Cells in V1: there are more cells that respond to vertical and horizontal edges than oblique edges
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Cortical components in visual perception : Receptive Fields
- Retinal Ganglion Cell (RGC)
- Simple cortical cell
- Complex cortical cell
- Hypercomplex cell
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Retinal Ganglion Cell (RGC)
receives info from lots of photoreceptors in a cricular patter
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LGN cells
Converge on cell in V1 that responds to sequence of circular patterns = edge
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Simple Cortical Cell
responds to simple sine wave with horizontal, vertical, oblique orientation
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Complex Cortical Cell
Rows of circular field that responds to moving edge with particular orientation
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Hypercomplex Cell
In V2 oriented edge that's moving but it stops --> corner
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Color in Visual Perception
- Spectrum -- Trichromaticity
- Cortical area V4
- Color constancy, Context Effects
- Color and After Effects, Pop-Out
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Light: what's it made of?
- Consists of photons at various wavelengths
- Visible: 400-700nm
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Trichromatic explanation of Color
Three color receptors: cones, long-, medium-, short gama sensitivity and rods
- rods = respond to green and brightness/dimness
- cones = have long and short sensitivity
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Anatomy of color perception
- V1 cell can respond to color --> blobs
- V4 = located along collateral sulcus, 1st major convergence of color info, output to ventral and dorsal streams, basic color processing goes to dorsal and ventral streams
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How is color perception sensitive to context?
- Reflected light depends upon light source
- Clothing matches when you dress indoors, but not outdoors
- Mutual inhibition of color-responsive cells
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Explain an after-image
- Activation of a subset of cells by image (yellow, blue-green, rods in both locations)
- Blank screen - relative increased activation of other cells
- Can be observed with color and orientation sensitive cells
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Anomalous photopigment
- Colorblindness
- X-linked effect
- Protonomaly
- Deuteranomaly
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Missing photopigment
- X-linked effect
- Protonopia - no red
- Deuteranopia - no green
- Tritanopia - no blue
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How do we see depth?
- Oculomotor cues : distance
- Binocular cues: two eyes
- monocular: organization
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Oculomotor Depth involves...
- Convergence: direction of each eye
- Accomodation: lens focus
- Increased muscle strain is a cue to proximity
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Binocular Depth involves...
Two different views: focus beyond the image, separate images on retina, perception of depth
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Monocular Cues
- Interposition: One object in front of another
- Size: large is usually closer
- Perspective: distances converges on a vanishing poing
- Motion parallax: near items/far items move in opposite directions
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What area is involved in Motion Perception?
V6 Flow fields vs. object movement, detects self moving v. object moving
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Audition Pathway
Hair cells bend --> voltage change in membrane --> NT release --> spiral ganglion cells transport message to MGN of thalamus --> auditory cortex in temporal lobe
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Audition: receptors and transduction
- Air pressure wave to motion tympanic membrane, ossicles, fluid in cochlea
- Displacement of basilar membrane bends hair cells
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Regions on the auditory cortex
- Primary Auditory cortex
- Belt Region
- Parabelt region: anterior/posterior
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Primary Auditory Cortex
Responsive to pitch
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Belt region
responds to combos of sound, complex stimuli
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Anterior parabelt region
- analogous to ventral 'what' stream in vision
- sound recognition and identification
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Parabelt posterior region
analogous to visual dorsal 'where' stream
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Things involved in Auditory Perception
- Pitch
- Intensity
- Timbre
- Location
- Masking
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Pitch: what is it and how is coded in the cochlea?
- Defined by frequency of sound
- Cochlea has labeled line place coding approach
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How is low pitch coded?
frequency and rate coding
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How is pitch from 200+ coded?
- place coding
- speech occurs where the overlap of place and rate coding is
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Intensity
The more cells that are firing the louder the sound
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Timbre
phase is the reason why we hear it as one sound and not multiple sounds
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Properties of Sound Localization
- Interaural Time Difference
- Interaural Intensity
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Interaural Time Difference is...
- Most important cue
- Processed in the superior olive where circuits of cells respond to relative arrival time
- Broader bandwidth = better localization
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Interaural Intensity difference is a function of...
Shadowing: a decrease in intensity on the opposite side of localization, most effective for high frequencies
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Optimal sound localization requires...
head or the sound source to be moving
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Cone of confusion
- Arrival times only give direction in one dimension
- equal arrival means source is at the midline
- Ambiguity is reduced by the pinna
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Masking: What is it?, What is its task? What are its properties
- A 2nd auditory stimulus makes the 1st stimulus harder to detect
- Task is segregating two simultaneous stimuli
- Frequency overlap, similarity, and critical band increase masking (2 octaves)
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What are the two basic characteristics of perception that may be detected?
- Is there a stimulus or not
- Has the stimulus changed or not
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What are the two types of thresholds?
Auditory and Difference
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Absolute Threshold
Minimum stimulus magnitude which can be reliably detected
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Difference threshold
- Minimum change in magnitude detectable as a change
- The 'just noticeable difference' (JND)
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Pros and Cons of Method of Limits
- Pros: moderately quick
- Cons: can have considerable error due to bias in responding
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Pros and Cons of Method of Constant Stimuli
- Pros: the most precise measurement of the threshold
- Cons: the slowest method
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Pros and Cons of Method of Adjustment
- Pros: Very quick
- Cons: most subject to error, very imprecise
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Properties of Signal Detection Theory
Sensitivity and Bias
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Signal Detection Theory : Sensitivity --> What is the goal?
Goal is to determine when an actual signal occurs against the background noise
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Signal Detection Theory: Bias
There is always a tendency to respond positively or negatively and that can be affected by experience
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Failures of Recognition
- Prosopagnosia
- Pure Word Deafness
- Luria's Pure Alexic Pt.
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Prosopagnosia
- Cannot recognize faces
- Can recognize voice and components of face
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Pure Word Deafness
- Cannot recognize, comprehend speech
- Hearing otherwise intact
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Luria's Pure Alexic Pt.
- Sudden onset acquired alexia
- Could see, comprehend speech
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Perceiving a picture depends on?
Context and relatedness to study scene
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Marr's Algorithm: what is it? 4 levels of representation?
- Early computer model for visual perception/recognition
- Primary concern: identifying 3D objects despite variation in 2D shape
- 4 levels of representation:
- Retinal (image) level
- Primal sketch
- 2 1/2-D
- 3-D
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Properties of retinal (image) level
- Pixels code level of brightness
- Flat image
- Like b/w TV picture
- Resolution: 8 bit (0-255)
- This is the info available to photoreceptor matrix
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Properties of Primal Sketch
- Pixels coded as -127-0 and 0 - +127
- Algorithm searches for zero crossings
- edge
- line segment
- Contrast = magnitude of difference at edge
- Primal objects, 'blobs' are patches of light or dark w/border of zero crossings
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Properties of 2 1/2-D Sketch
- Algorithm computes edges, contrast ratios, and blobs
- probabilities for shading, contrast
- Builds image (proababilities for 3-D on a 2-D surface)
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Properties of a 3-D representation
- Volumetric images are computed
- uses 'geon'-like template-elements to construct objects
- Incorporates Gestalt principles to estimate object shape
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Theoretical approaches to Object Recognition
- Template Theories
- Feature Theories
- Structural Theories
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Letter-Word Recognition: Feature Approach
- Feature (bottom-up approach)
- Examine letter for feature properties and compare those features
- Feature examples: edges, orientations, locations
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Letter-Word Recognition: Template Approach
- Concept driven
- Compare perceived objects with template
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Posner Letter Matching: what is its task?
- Task is to indicate if letters are same or different
- Physical appearance
- Name
- Vowel/Consonant: vowels quicker than consonants
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Feature Matching: what is its task?
- Task, name the letter
- Tachistoscopically presented
- Subjects respond by voice
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Pandemonium
- Combines feature and template analysis
- Four levels of analyzer modules (daemons)
- Image, Feature, Cognitive, Decision
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Pandemonium: Stage 1: Image Daemon
- Encodes the visual signal
- Extracts features: contrasts, edges, borders
- Each feature excites corresponding daemons in stage 2
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Pandemonium: Stage 2: Feature Daemons
- Analyze/Recognize features in the image
- Each daemon reports the strength of evidence for its feature
- Lines at a given orientation
- Curves
- Corners at a given orientation
- Combinations of features excites corresponding daemons in stage 3
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Pandemonium: Stage 3: Cognitive Daemons
- Daemon reports strength of its particular combination of features
- Lines meeting at oblique angle excite cognitive daemons representing A, Y, K
- Parallel lines excite cognitive daemons representing E,F,H,N,M,U
- Horizontal lines excite cognitive daemons representing A,E,F,H
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Pandemonium: Stage 4: Decision Daemon
- Listens to the pandemonium of shouting cognitive daemons
- Loudest daemon wins
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Limits of Info. Processing
- If the initial info processing involves
- sensory storage, filtering, pattern recognition, then reporting the output for awareness
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Sperlings sensory registers
- Pre-cuing: 10 items
- Simultaneous: 9 items
- Matches historical estimates of span of apprehension
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Word Superiority Effect
- Letter recognition is affected by context
- implies data-driven processes are sensitive to top-down modulation
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Interactive Activation Model: Why was it developed? What kind of processing does it use?
- Developed as explanation for WSE
- Letter ID/detection better in words than nonwords
- Better in words than for letters alone
- Combines top-down and bottom-up processing
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Activation node of Interactive activation model results in...
- The bottom up activation of all compatible nodes at the next higher level
- The inhibition of other nodes at that level
- The inhibition of incompatible nodes at lower levels
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Dual Route Model: What was it developed? What processing does it use?
- Developed as an alternative to IAM
- Explains acquired dyslexia
- speech/reading comprehension
- Primarily feed forward activation/ processing
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Speech Recognition Properties
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Formant
- Bands of sound energy
- Change across time = speech
- Lowest formant is principal pitch of voice
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Vowels
Relative position of formants
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Consonants
Rapid changes in formant positions
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Prototype matching
- Phonemic decoding - words, lexical nodes
- Parallels dual route model of reading
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Motor Matching
- Phonemic decoding
- Activates motor patterns for speech
- Mirror neurons
- Viewing speaker- biases perception = ventriliquism
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Cohort Model
- Phoneme units activated
- Inhibits lexical units of other phonemes
- Syntax and semantics modulates baseline activation of lexical units
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Organizing the Perceived World Theories
- Structural Theory
- View Based Theory
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Structural and View Based Theory Properties
- Pragnanz
- Proximity
- Similarity
- Common Fate
- Good Continuation
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Pragnanz
Perceived objects tend to be as simple as possible
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Proximity
Perceived objects tend to have components near to each other
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Similarity
repeated features are grouped into large 'objects'
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Common Fate
Things moving in the same direction are grouped together
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Good Continuation
Points that, when connected, for straight or simple curved lines are perceived as belonging together
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Biederman's Recognition by Components Model (RBC)
- Utilizes a shape alphabet
- Geons
- RBC proposed for recognition of "basic category level"
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Evidence for RBC
- Recognition of incomplete objects depends on geons
- Complex objects are more resistant to the removal of individual geons
- The relationship among geons is critical
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View-Invariant recognition
Cues to shape obscured
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View-dependent recognition
Failure because of uncommon perspective
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Recognition and Response Times are dependent on ....
View
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What is Attention?
- Difficult to define...but you know when you are paying it
- What happens at the points of rest in the stream of consciousness
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ADHD
Difficulty organizing tasks and sustaining attention
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Hemispheric Neglect
- Ignores info from left side
- dressing, shaving, cancellation task, flower drawing, clock drawing
- Not poor sensory response, lack of attending
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Hyperarousal PTSD
- Excessive scanning
- Hyper-aware of possibility of danger
- Easily distracted
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Rumination in Depression
- Unable not to stop thinking about depressing topics
- Concentrates well, but on one or one set of items
- Cannot disengage attention
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Attention implies...
- selectivity
- shiftable
- divisible
- a finite resource
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Attention is a mechanism that...
- focuses processing and awareness on subset of sensory info
- when another focus is possible
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Dichotic Listening
Subject could only provide info about the speaker they were told to attend to, and only surface things (gender) in the other
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Early Selection Theory
- Selective Filter
- Limited capacity channel
- Detection-ID device
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Early Attenuation Theory
- All info analyzed for
- physical properties
- linguistic properties
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Late Attenuation Theroy
- All info processed to the level of ID
- selection occurs after ID, info not passed to working memory decays quickly
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Characteristics of Attention
- Paying Attention requires effort
- Attention functions like a spotlight
- Some things automatically attract attention: they "pop-out"
- There is a limited-capacity route to attention
- Different characteristics describe attention attracted automatically and attention directed by volitional control (controlled v. uncontrolled)
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Kahneman's Attention
Attentions a limited resource
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