reverse terms pt.II

Question 1

Potential ambiguity of an object seen from one viewpoint

Answer 1

variable views

Question 2

Determining the “true” shape of an object when some of its contours are hidden

Answer 2

image clutter

Question 3

Need to be able to recognize an incredibly large number of objects in the world

Answer 3

object variety

Question 4

(lower level processes)
Represent Edges
Figure-ground (assign border ownership)
Grouping
Interpolation of missing edges

Answer 4

Perceptual Organization

Question 5

(higher level process)

Match perceptual representation to those stored in memory

Answer 5

Object Recognition

Question 6

mexican mat: ganglion cell, small hat is all the increased spatial freq info and big hat is course small spac freq info

Answer 6

Edge detection

Question 7

with the ink edges are appropriately assigned, region in front ‘owns’ the border. If slipped don’t know what’s figure-ground. Amount of light in oral field identical but firing rate for light on dark is higher. Activation is V2 higher if presented with one circle with overlapping triangles then dif vs one circle then same one. (strong response to change in border ownership)

Answer 7

Border ownership:

Question 8

(structural description theories)
Viewpoint invariant representation
Biederman (recognition by components), Marr
Based on primitives, called 3D “geons”
These are fundamental 3-dimensional shapes that are easily discriminable under a wide variety of conditions
Defines parts and the spatial relation between them
In-category distinctions difficult.
-We’d be a lot worse at object recognition if this were the case

Answer 8

Prototype matching

Question 9

Viewpoint-dependent representation (if change orientation we suddenly suck) therefore okay but need lots of representations for each object (unless population code, then not more neurons…more patterns of neurons)

Answer 9

Template matching

Question 10

• Area lower down (like V2) location more important [NB for representation of the world]
• info hierarchical in ITC
• dif aspects of stim processed by dif anatomical areas but all must work together
• top more vauge (animate vs inanimate) snd lower is finer processing like (FFA or ob?), even finer (bottom would be is it eyes/lips of the face)

Answer 10

Heirarchical Coding

Question 11

• red-green, blue-yellow, and black-white were organised in some opponent fashion so that the activation of one would supress the other
• On this basis it was possible to explain many colour phenomena
• Card sorting
• Colour afterimages
• Descriptions of colour mixtures

Answer 11

Opponent-Process Theory

Question 12

Lightness is a perceptual experience NOT a physical quality of an object
Reflectance (albedo) is a physical surface quality proportion of light that is reflected independent of the source of light

Answer 12

Lightness Constancy

Question 13

Single opponent cell normally responds with
excitation to long wavelength (“red)
inhibition to medium wavelength (“green”)
at baseline to equal amounts of red & green light (“yellow” or “white”).
Therefore,
During adaptation to a red patch, the cell (and/or the cones that send excitatory input to that cell) responds strongly and gets fatigued
After adaptation, the cell is fatigued and not responding as strongly as it normally would (i.e. responding with inhibition when white background presented)
Therefore, we experience a green afterimage in the area of the retina where the adaptation occurred.

Answer 13

Colour Afterimages

Question 14

Objects look the same colour in a broad range of illuminants - apple is red in store and at home
However, recall
light at eye = reflectance x illuminant
so how is it, that the colour of an object is constant in different illuminants?

Answer 14

Colour Constancy

Question 15

In any given scene, the region that reflects the most light is perceived as white (or as the lightest shade of gray in the scene), and the lightness of every other region is perceived in relation to that anchor point.
If the scene consists of regions under different amounts of illumination, the visual system applies the rule separately in each illumination zone.

Answer 15

Anchors

Question 16

No colour vision
Poor acuity
Photophobic

Answer 16

Rod Monochromats

Question 17

No colour vision

Otherwise normal vision

Answer 17

Cone monochromats

Question 18

Very rare; often associated with other problems
May be considered as “true” colour blindness
Can match all wavelengths by adjusting intensity of any other single wavelength
two forms

Answer 18

Monochromacy

Question 19

Can match all wavelengths by adjusting intensity of two other wavelengths
Comes in three forms:
-Protanopia 
-Deuteranopia
-Tritanopia

Answer 19

Dichromacy

Question 20

(more common)They are missing the long and medium-wavelength pigment, respectively
Individuals see short-wavelengths as blue
Above neutral point, they see yellow
Occurs in more often in males than females (X-linked)

Answer 20

Protanopia & Deuteranopia

Question 21

They are missing the short-wavelength pigment
Individuals see short wavelengths as blue
(rare) Above neutral point, they see red
Equally common in males and females

Answer 21

Tritanopia

Question 22

Damage to the central visual system (V4 and surrounding areas)
very rare
sensitive to wavelength differences but unable to see colours
everything seen in shades of gray

Answer 22

Cerebral Achromatopsia

Question 23

light consists of a single wavelength

Answer 23

Monochromatic

Question 24

light having a wide range of wavlengths

Answer 24

Heterochromatic

Question 25

white light… means without, colourless

Answer 25

Achromatic

Question 26

• is a spectral colour (red, green) that has one wavelength
• Non-spectral is a combo of wavelengths (like pink and purple)
• the “colour” of the target
• wavelength

Answer 26

Hue

Question 27

• richness of colour (dark blue, baby blue, light white-ish blue)
• the degree of whiteness in the target
• spectral purity

Answer 27

saturation

Question 28

• grey levels
• the perceived intensity of the target
• luminance

Answer 28

brightness

Question 29

• paints
• gets darker, loses more wavelengths
• the source produces a wide range of wavelengths, some of which are eliminated (absorbed)

Answer 29

Subtractive Mixing

Question 30

• adding more wavelengths, gaining energy,
• gets whiter increase luminance
• TV, spotlights
• wavelengths from different sources are combined
• final result is lighter than the components (less saturated because we are reducing the purity of the light – adding broader range of wavelengths)

Answer 30

Additive Mixing

Question 31

• Trichromatic Theory: 3 cones S(B) M(G) L(R)

- Opponency Theory: colour after effects, G+R and B+Y and W+B seem to go together this is the retnial ganglion cell

Answer 31

Two Stage Model

Question 32

• Proposed by Young and Helmholtz (1800s)
• Three different receptor mechanisms are responsible for color vision
• Behavioral evidence:
• Color-matching experiments Observers adjusted amounts of three wavelengths to match a comparison field to a test field
• later tested and found pigments that responded maximally to Short med and long wavelengths

Answer 32

Trichromatic Theory of Color Vision

Question 33

• Each cone mechanism has only one dimension of response (i.e., firing rate or number of action potentials) and that reflects the amount of light absorbed by the cone
• As such is unable to distinguish changes in intensity of a light from changes in the spectral composition (i.e., wavelength)
• It is impossible to work backward from the response of a single cone to determine the wavelength of the light that caused the response
• The output of a photoreceptor is a product of the intensity of the light and the sensitivity of the receptor to that particular wavelength:
• Response = Stimulus Intensity * Relative Sensitivity to Wavelength

Answer 33

Principle of Univariance