Exam 2-Neuroscience of Perception

what is the “what” pathway

the ventral pathway; concerned with name and function

what is the “where” pathway

the dorsal pathway; concerned with shape and location

can a V1 neuron have boundary discrimination?

no, it can only recognize the tilt

can a V2 neuron have boundary discrimination?

yes

what is Agnosia?

the failure to recognize objects even when you can see them

do IT neurons have big or small receptive fields?

big

what do IT neurons not respond to?

they do NOT respond to spots or lines well

what do IT neurons respond well to?

stimuli such as hands, faces, objects

what is it called when the properties of the whole object take precedence over the properties of parts of the object?

global superiority effect

What stimulus do V4 neurons respond well to?

fans, spirals, pinwheels (more than just bars of light or spots)

What is it called when they take fMRI scans of a participant looking at lots of different images and then train a computer model to recognize brain activity from each category, then test the computer model to see if it can recognize an image it hasn’t been trained on

Decoding Method

What is the proposal that the visual system recognizes objects by matching the neural representation of the image with a stored representation of the same “shape” in the brain?

Template Theory

What is the description of an object in terms of its parts and its relationships between those parts?

Structural Description

What are the "geometric ions” out of which objects are built?

Geons

What is processing based on an analysis of the entire object or scene and not on adding together a smaller set of parts or features?

Holistic processing

what are the three steps to color perception?

detection, discrimination, appearance

describe step one in color perception:

1. detection: wavelengths of light must be detected in the first place

describe step two in color perception:

2. discrimination: we must be able to tell the difference between one wavelength (or mixture of wavelengths) and another

describe step three in color perception:

3. appearance: assign perceived colors to lights and surfaces in the world and have those perceived colors be stable over time, regardless of different lighting conditions

What do S-cones detect?

short wavelengths, blue range

what do M-cones detect?

medium wavelengths; green range

what do L-cones detect?

long wavelengths, red range

what is the principle of univariance?

an infinite set of different wavelength and intensity combinations can elicit exactly the same response from a single type of photoreceptor

all rods contain:

rhodopsin

do rods obey the principle of univariance?

yes

rods are mainly active under:

scotopic conditions (dim light)

what is the trichromatic theory of color vision?

theory that the color of any light is defined in our visual system by the relationships of three numbers, the outputs of three receptor types not known to be the three cones

trichromatic theory is called:

Young-Helmholtz theory

What are metamers?

different mixtures of wavelengths that look identical; more generally, any pair of stimuli that are perceived as identical despite physical differences

what are non-spectral colors?

colors that do not correspond to a single wavelength of light (for example, purple or magenta)

What are LGN cells response to Red vs Green

some LGN cells are excited by L-cone activation in the center, while inhibited by M-cone activation in their surround (and vice-versa)

What are LGN cells response to Blue vs Yellow

other cells are excited by S-cone activation in center, inhibited by (L+M)-cone activation in their surround (and vice versa)

Who discovered illegal color combinations?

Ewald Hering

What is opponent color theory?

the perception of color depends on the output of three mechanisms, each of them based on an opponency between two colors: red and green, blue and yellow, black and white

What is it called: an afterimage whose polarity if the opposite of the original stimulus

Negative afterimage

What is color-anomalous?

a term for color blindness

deuteranope

no M-cones

protanope

no L-cones

tritanope

no S-cones

cone monochromat

only has one cone type (true color-blindness)

rod monochromat

no cones at all, true color-blindness, bad visibility in bright light

what is color assimilation?

when colors bleed into another, and give the appearance of being mixed (example: the balls with the lines or the group of people with the colorful grid over it that makes it looked colored)

What is color constancy? and example

the tendency of a color to appear the same under a variety of illuminants (example: the strawberry bowl with the blue cast over it)

what is color contrast?

an effect where the color of one region induces the opponent color in another region

what is additive color mixing?

a mixture of lights creates white

what is subtractive color mixing?

a mixture of pigments creates black