3. Object Perception Flashcards
How is ‘seeing’ converted into ‘perception’?
-
...encodes...image features -
...is provided with this info after... ......- Process of the
...pathway
o...->...->...->...
How is ‘seeing’ converted into ‘perception’?
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Early visual systemencodeslocalimage features -
Brainis provided with this info afterretinal processing Combined into global structuresHierarchical organisation- Process of the
VENTRALpathway
oV1->V2->V4->infero-temporal cortex
What is the job of V1 (primary visual cortex)?
Identifies ... such as ... and .... Starts in ... and .... ... get larger and larger as we move more ...; subject to ... where the ... which results in ... being affected.
What is the job of V1 (primary visual cortex)?
Identifies local/low-level features (contours) such as where ear lobes are and size of space between nose and lips. Starts in retinotopic organisation and orientation selectivity. Receptive fields get larger and larger as we move more peripheral; subject to surround suppression where the centre is overwhelmed by information in the periphery which results in centre vision being affected.
Explain how V1 integrates contours.
Local level of contour is processed by V1.
As long as elements lining up are close enough together, the brain can link them up.
Therefore the straight line (left) is easier to see the swerve (right) because the elements hold a very similar angle, whereas when we dim the other gratings, we can identify the swerve easier.
What is the job of V2?
V2 neurons are sensitive to ... and ..., and they .... They are able to ... even when ...; this is useful for ....
What is the job of V2?
V2 neurons are sensitive to orientation and colour, and they contour the processing of contours. They are able to infer contour even when they are not actually there; this is useful for the brain being able to fill in partially occluded natural scenes.
Explain this experiment with V2 neurons.
1 is more responsive than 4 as there is the illusion of an occluded objected.
4 is composed of basic line elements, and is more of a geometric illusion, tapping into Vernier acuity (level of line displacement)
2 - illusion of continuing line, 3 - boundaries are shut off, so no illusion.
V2 is a lot more responsive to 2, the perception of the illusory lines.
What is the role of V4?
Intregration of ... into .... The more ... are, the more difficult it is to ....
Amblyopes require a ... in order to ... as the pathways aren’t developed as much. ... is easier for amblyopes than .... There is too much info for the amblyopic eye’s pathways to process given the reduced development.
What is the role of V4?
Intregration of local cues into global shape percepts. The more varied the local elements are, the more difficult it is to integrate them.
Amblyopes require a higher threshold in order to integrate the local into global as the pathways aren’t developed as much. Local processing is easier for amblyopes than global processing. There is too much info for the amblyopic eye’s pathways to process given the reduced development.
What is the role of the higher cortical areas?
The ... is considered a key area which ....
Different parts of the brain are used for ... or .... E.g. there is a part of the brain ....
What is the role of the higher cortical areas?
The infero-temporal cortex is considered a key area which supports object perception.
Different parts of the brain are used for identifying different things or types of objects. E.g. there is a part of the brain particularly triggered by faces.
Describe visual agnosia.
It is the ..., due to ....
Two types:
* ... - can’t ...
* ... - can’t ...
Describe visual agnosia.
It is the inability to recognise visually presented objects, due to damage somewhere along visual pathway.
Two types:
* Aperceptive - can’t integrate the component visual features in a global whole
* Associative - can’t identify the object without required knowledge of it
Describe prosopagnosia.
..., due to ...; ability to .... Can be either ... or .... Can compensate with other factors such as ... or .... Can identify the ... but ....
Describe prosopagnosia.
Face blindness, due to damage to the fusiform face area; ability to recognise faces is impaired. Can be either acquired or congenital. Can compensate with other factors such as voices or big teeth. Can identify the individual components of a face but can't integrate them.
