lecture 3

Question 1

what is accomodation

Answer 1

Adjustments of the lens so that
light is focussed on the fovea of the
retina

Question 2

describe the parvocellular pathway (P)

Answer 2

Ventral “what” pathway

sensitive to colour and fine detail. most input comes from cones

Question 3

describe the Magnocellular Pathway (M)

Answer 3

Dorsal “where” pathway.

most sensitive to motion. Most input comes from rods

Question 4

describe the simple cell vs complex cell

Answer 4

simple cell = one layered neurons network

complex cell = multiple layered neurons network

Question 5

describe the Zeki functional specialisation – V1 and V2

Answer 5

V1 & V2

Basic visual processing

Question 6

describe the Zeki functional specialisation – V3 and V3a

Answer 6

Form perception (especially of moving stimuli)

Question 7

describe the Zeki functional specialisation – V4

Answer 7

Colour perception

Question 8

describe the Zeki functional specialisation – V5(MT)

Answer 8

Motion perception

Question 9

What is the binding problem

Answer 9

given functional specialisation. how is information combined and integrated

Question 10

how is the binding problem solved

Answer 10

binding by synchrony –> detectors firing together = single object
neural activity patterns over time

Question 11

What two visual systems exist

Answer 11

ventral stream

doral stream

Question 12

describe the ventral stream

Answer 12

vision for perception
indepedent of observers perspective (allocentric)
consious, fast processing input from fovea

Question 13

describe the dorsal stream

Answer 13

vision for action
egocentric
unconsious

Question 14

describe visual form agnosia

Answer 14

• Damage to lateral occipital cortex
• Intact visually-guided movements
• Poor object recognition

Question 15

describe optic ataxia

Answer 15

• Damage to posterior parietal cortex
• Poor at making precise visually-guided movements
• Intact object recognition

Question 16

describe the double dissociation of vision for perception, vision for action, visual form agnosia and optic ataxia

Answer 16

vision for perception(ventral stream) is not working in visual form agnosia.
vision for action(dorsal stream) is not working in optic ataxia

Question 17

regarding colour vision, what is hue

Answer 17

distinguishes red from yellow or blue

Question 18

regarding colour vision, what is brightness

Answer 18

The perceived intensity of light

Question 19

regarding colour vision, what is saturation

Answer 19

Allows us to determine whether a colour is vivid or pale

Question 20

describe the opponent-process theory

Answer 20

three receptor complexes with opposing actions. These three receptors complexes are the red-green complex(inhibitoir), the blue-yellow complex(red+green = excitatoir but blue is inhibitoir)

and the light dark complex(excitatoir).

According to the opponent-process theory, these cells can only detect the presence of one color at a time because the two colors oppose one another.

You do not see greenish-red because the opponent cells can only detect one of these colors at a time.

Question 21

how if the absolute treshold defined

Answer 21

absolute treshold is defined at the intensity at which 50% of the stimuli are detected

Question 22

describe the signal detection theory

Answer 22

differentiates between actual sensitivity and response bias.
no signal = noise (internal and/or external) = normal distribution
signal = the signal..
signal + noise = normal distribution but shifted to right.
d’=sensitivity index = distance of the mean of noise distribution to the mean of the signal+noise normal distribution

Question 23

regarding the signal detection theory, low d’

Answer 23

low sensitivity or low signal

Question 24

regarding the signal detection theory, high d’

Answer 24

high sensitivity or high signal

Question 25

desribe what we can do with the results of SDT

Answer 25

``` we can construct a matrix miss = signal is present but no response hit = signal + response correct rejection = no signal no response false alarm = no signal + response ```

Question 26

describe the criterion in SDT

Answer 26

signal must be above certain criterion level for the subject to notice the stimulus

Question 27

what is the just noticeable difference

Answer 27

its the smallest difference between stimulus S1, intensity I1, and stimulus S2, intensity I2 . at which the subject can tell S1 and S2 are different = deltaI

Question 28

Describe Weber's law

Answer 28

JND , delta I increases proportionally with the intensity I1, at which S1 is presented. therefore K = delta I / I1 and k is constant

Question 29

Describe monocular depth perception cues

Answer 29

``` pictorial cues can be processed by one eye, e.g. linear persepctive(train rails),texture gradient, interpositon, motion parallax, ```

Question 30

Describe occulomotor depth perception cues accomodation

Answer 30

depend on the muscles that move the eye accomodation: Muscle tension provides cue to whether eye isfocusing far or near away.

Question 31

Describe occulomotor depth perception cues | vergence

Answer 31

depend on the muscles that move the eye Vergence: Relative inward rotation of eyes also provide cue to distance of object

Question 32

Describe binocular depth perception cues => binocular disparity

Answer 32

``` Slight differences in the two retinal images – Disparity and blur – Outside the region of fixation, blur is more precise (and hence more useful) than disparity for depth perception ```

Question 33

describe additivity (integrating cue information)

Answer 33

All the information from different cues is simply added | together

Question 34

describe selection (integrating cue information)

Answer 34

Information from a single cue is used, with information from the other cue or cues being ignored

Question 35

describe multiplication (integrating cue information)

Answer 35

Information from different cues interacts in a multiplicative fashion

Question 36

describe the relation between size perception and familiarity(haber & levin)

Answer 36

Size perception of objects depends on memory of their | familiar size rather than solely on perceptual information

Question 37

describe blindsight

Answer 37

Responding appropriately to visual stimuli in the absence of conscious visual experience

Question 38

blindsight is associated with ...

Answer 38

severe brain damage to V1

Question 39

describe action blindsight

Answer 39

Some ability to grasp/point at objects • Relies on dorsal stream

Question 40

describe attention blindsight

Answer 40

Ability to detect objects and motion, with a vague conscious feeling • Relies on intact posterior parietal cortex in dorsal stream

Question 41

describe agnosopsia(blindsight)

Answer 41

* Patient denies any conscious awareness * Some ability to discriminate form and wavelength * Relies on ventral stream

Question 42

describe masked semantic priming

Answer 42

Faster responses to CAT after masked DOG (a semantically related word) than after an unrelated masked word (e.g. PEN) even if subjects are not aware they have seen DOG or PEN