L25 - ObjectPerception_2016(AMcK) Flashcards Preview

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Flashcards in L25 - ObjectPerception_2016(AMcK) Deck (13):
1

What techniques have been used to determine how the brain enables us to perceive objects?

fMRI, lesion studies, animal studies, single cell neurophysiology

2

What info is fed-forward from V1?

-Discrete orientation info
-colour
-Linked borders/contours
-Some boundary and edge info
*Starting point (retinotopic organisation and orientation selectivity)

3

There are long-range interactions between neurons

Previously you could not see the patch in the middle by itself. Put two patches next to it and suddenly you will be able to see the one in the middle. This is because there are cells that are encoding similar features that are connected by horizontal connections that amplify the signal

There are long-range interactions between neurons

Previously you could not see the patch in the middle by itself. Put two patches next to it and suddenly you will be able to see the one in the middle. This is because there are cells that are encoding similar features that are connected by horizontal connections that amplify the signal

4

x% of orientation difference is required for elements to be viewed as a contour

30 or less than

5

What info does V2 process?

Orientation, colour, continue processing of contours (illusionary contours - we see these contours as often objects are partially occluded in natural scenes yet the visual system enables seamless completion of these objects)

6

T/F - V1 cells can also respond to illusory contours like V2 cells

F- V1 cannot

7

What info does V4 process?

Integration of local cues into global shape percepts

8

!What are two types of stimuli used to study global integration of form cue?

1) Glass patterns
Allow us to control orientation information and different amounts of coherence

2) Global shapes not from texture

9

fMRI study is looking at what sort of stimuli can activate certain cortical areas. When shown a concentric, radial or parallel thing - how did:
a) V1 respond
b) V4 respond
c) FFA respond

a) V1 responded equally to all

b) V4 responded more to concentric and radial patterns as these stimuli encode an object structure

c) FFA responded to concentric as the face is quite round

10

What is the role of the lateral occipital cortex? Inferior occipital cortex?

Global shape processing
Texture analysis

11

Aperceptive agnosia

Can't integrate the component visual features into a global whole (but low-level colour, motion, orientation perception is intact) E.g. if asked to draw a copy of an object, might draw major features but not connectivity

12

Associative agnosia

Can't identify the object with the required knowledge of it. May be able to copy it but don't recognise what it is

13

Prosopagnosia is? Due to damage to?

Face blindness, Damage to FFA