V1 and V2 = involved in basic visual processing V3 = deals with forms of perception V4 = deals with colour perception V5 = processes motion perception

Feature detectors in V1:

Only certain neurons would fire at specific features on visual screen measured cat's cortex found some neurons reacted specifically to dots, lines, movement etc suggests each element of visual field is broken down within the visual cortex stage

Where does Form (shape) processing happen?

V1, V2, V3, V4 process object shape and form

Where does colour processing happen?

In the V4 research found more activation in V4 area when looking at colour clips

Where does motion processing happen?

V5 - ppts had TMS (magnetic stimulation) to disrupt V5 - ppts had an impaired ability to discriminate between different speeds

What is Feature integration theory?

Selective attention plays a role suggestion 1: binding-by-synchrony - features from single object fire in synchrony suggestion 2: patterns of neural activity over time help coordinate binding

What is the dorsal pathway?

Where something is visual-for-action processes spatial info to guide movement egocentric (represents object in space relative to self) short-lived representations usually unconscious

What is the ventral pathway?

What something is named vision-for-perception identifies objects allocentric (labelling of objects without reference to self) sustained representation usually conscious input from the fovea (details from the cones)

What happens when there is dorsal stream damage?

Optic Ataxia: poor guided movement

What happens when there is ventral stream damage?

Visual form agnosia (trouble naming visual forms)

Perceptions of visual illusions

Researchers found when pointing (using vision-for-action system) the illusion size 5.5% when verbalising a response (using vision-for-perception system) the illusion size was 22%

Colour vision: what is the trichromatic theory?

The theory that there are 3 types of cones identified

Opponent-process theory:

When some colours such as red and green, oppose one another in processing similarly with blue and yellow, and light and dark

What is dual process theory?

Combination of the trichromatic and opponent process theory

What is colour constancy?

The tendency for an object/surface to appear to have the same colour despite change in wavelengths i.e. blue mug is blue even if reflections on the mug show a different colour

What is depth perception and how do we do this?

Being able to judge depth of an object we do this by using: linear perspective texture interposition - something is infront of other objects shading familiar size image blur motion parallax - when we move sideways and diff. objects move at diff speeds

What is Binocular disparity?

Slight different in 2 retinal images

What is Size constancy?

Tendency for objects to appear the same size whether their size in the image is large or small