ND - Object Perception - Week 1

Question 1

Describe the visual ventral pathway.

Answer 1

V1 - V2 - V4 - infero-temporal cortex

Question 2

What does V1 do (3)?

Answer 2

Provides low-level information for contour shape processing (contour integration)
Retinotopic organisation
Orientation selectivity

Question 3

Are there short or long range interactions between neurons in V1?

Answer 3

Long

Question 4

Describe surround suppression. Which layer is it processed in?

Answer 4

V1
Lateral interactions that help define boundaries
The apparent contrast of objects depends on their background

Question 5

What are V2 cells sensitive to (2)? What do they do?

Answer 5

Orientation
Colour
Continue the processing of contours
Also responsible for illusory contours (think of a white square whose edges are overlapped by circles. You still see the white square even though you only have incomplete circles as a que).

Question 6

What does V4 do?

Answer 6

Integration of local cues into global shape percepts

Question 7

Define visual agnosia.

Answer 7

Inability to recognise visually presented objects

Question 8

Define aperceptive agnosia. Give an example.

Answer 8

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

Question 9

Define associative agnosia.

Answer 9

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

Question 10

Define prospagnosia and why it occurs.

Answer 10

Face blindness, ability to recognise faces is impaired, but other object perception & cognition is intact.
Can identify individuals objects that make up a face, but can’t integrate into a complete facial percept.
Due to damage to the fusiform area (specific part of the human temporal lobe).

Question 11

Can prospagnosia be acquired or congenital?

Answer 11

Either