Psy 121, Study Guide for Lectures and Reading on Vision (Cont.)1

Psy 121, Study Guide for lectures and reading on vision (cont.)1

Psy 121 Fall, 2007

Study guide for Chapts 4 & 5, lectures of 9/72, Oct 2&4, labs of Oct 4/5

Required reading notes: In Chapt 4 of GRG, you may skip the section on Hearing, pp. 129-136 and in Chapt 5, you may skip the section on Other Modalities, pp. 187-188. There will be frequent references to materials in Chapt 3, and you should also look at the section on Consciousness in Chapter 8, pp. 303-308.

From Input to Output

Organization of psychological and neural processing

sensory neurons, motor neurons and the great in-between

reflexes

feedback and feedforward circuits

example of feedforward: compensation for eye movements (GRG pp 162-163)

parallel processing and the binding problem

“bottom-up” and “top-down”

the importance of attention

General Properties of Sensory Systems

empiricists, nativists

distal stimulus, proximal stimulus

dimensions of perception:

detection (absolute threshold)

signal detection theory

hits, misses, false alarms, correct negatives

sensitivity, response bias

discrimination (difference threshold)

Weber fraction

generalizations (perceptual constancies)

perceptual distortions (illusions)

dimensions of sensation:

stimulus quantity (intensity)

stimulus quality

sensory modalities

within-modality dimensions, for example:

features such as color (vision), timbre (audition), sweet/sour (taste)

spatial localization

temporal properties

neural coding of sensation:

transduction

stimulus intensity:

number of different neurons firing (recruitment)

frequency of firing of individual neurons

stimulus quality:

which neurons fire (neuronal specificity), for example:

modality specific neurons

topographic (spatially organized) projections

pattern theory

temporal properties: phasic/tonic responses

synchrony among neurons

Vision

properties of light: corresponding psychological dimension

intensity: brightness

wavelength(s): hue and saturation

spatial origin: spatial location

receptive fields of single neurons

what are they (GRG p.180)

how are they "mapped"? (GRG Fig 4.31)

the visual system (GRG Fig 5.41)

structure of the eye (GRG Fig 4.12)

the retina (structure of retinal microcircuits, GRG Fig 4.13)

optic nerves, optic chiasm, optic tracts

lateralization in the visual system

thalamic relay: the lateral geniculate nucleus (LGN)

visual cortex

primary visual cortex (V1)

further processing areas

dorsal and ventral pathways, parallel processing (GRG Fig 5.42)

processing in the retina

photoreceptors: rods and cones (duplex theory of vision: ways in which rods & cones differ)

chemical transduction: photopigments (visual pigments)

rhodopsin in rods

3 cone opsins (trichromatic color vision, primary colors)

spectral sensitivity curves

peripheral vs foveal vision

horizontal cells: lateral inhibition (GRG Fig 4.20)

ganglion cells (GRG p. 180)

P-cells (parvo cells): center-surround receptive fields (GRG Fig 4.32)

spatial discrimination

color opponency (opponent process color vision, complementary colors)

GRG Fig 4.28

M-cells (magno cells): movement sensitivity

Important point in lecture: an analysis of neuronal specificity and pattern theory in the retina

perceptual phenomena (retinal)

absolute (detection) thresholds

the rhodopsin spectral sensitivity curve

the cone spectral sensitivity curves (GRG Fig 4.24)

brightness contrast (e.g., GRG Figs 4.16 - 4.19) and lateral inhibition

negative color afterimage (GRG Fig 4.26): adaptation and color opponency

simultaneous color contrast: color opponency and lateral inhibition (GRG Fig 4.25)

II. processing in primary visual cortex (area V1, striate cortex)

retinotopic projection (spatial selectivity)

“feature detectors”

orientation selectivity (GRG Fig 4.23)

movement sensitivity: directional selectivity (GRG p. 161)

binocular receptive fields (basis of binocular disparity sensitivity, GRG p.157)

spectral sensitivity

cortical columns (modules)

neuropsychology: blindsight (GRG p. 305)

III. beyond V1, the "ventral stream": form detection and color processing (the "what" system)

area V4: color

inferior temporal cortex:

“geon” detectors, object detectors

e.g., face cells in the FFA (note fMRI findings in GRG pp. 306-307)

“grandmother cells” and the binding problem

neural synchrony, gamma band oscillations

form/object recognition

"feature nets" and simultaneous multiple constraint satisfaction (GRG pp. 176-178)

priming effects (GRG p. 177)

visual segregation or perceptual parsing

grouping principles (laws of perceptual organization): proximity, similarity, good continuation, closure, coherent motion

figure/ground

higher-order invariants

unconscious inference

perceptual phenomena

perceptual constancies

brightness constancy

size constancy

shape constancies

position constancy

illusions

subjective contours (GRG Fig 5.19)

geometrical illusions (e.g., Muller-Lyer illusion)

moon illusion

Ponzo illusion (GRG Fig 5.35)

ambiguous figures (GRG Figs 5.28 – 5.30)

impossible figures (GRG Fig 5.44)

neuropsychology (Chapt 3): agnosias

IV. Beyond V1, the "dorsal stream": motion processing, depth perception (the "where" or "how" system)

the parietal cortex

area V5 (MT): motion detection

Newsome’s microstimulation experiments

spatial frames of reference

perceptual phenomena

motion aftereffects (adaptation)

apparent (or stroboscopic) movement (GRG Fig 5.10)

induced motion (GRG Fig 5.12)

depth cues (GRG pp. 157-163)

binocular disparity (retinal disparity)

pictorial cues (monocular depth cues)

linear perspective, relative size, interposition, texture gradients

light & shadow

motion parallax, optic flow

neuropsychology: neglect syndrome (Chapter 3)

visual attention

involuntary (reflexive, exogenous) and voluntary (endogenous) orienting

visual search

feature-driven pop out

serial search for feature conjunctions

illusory conjunctions

attention and perceptual organization: ambiguous figures