Unit 3, Topic 2 - Visual perception

Question 1

Visual perception process

Answer 1

Reception, transduction, transmission, selection, organisation and development

Question 2

Visual reception

Answer 2

Light enters the cornea, passes through the pupil, and is focused on the retina by the lens. Receptors in the eye detect and respond to the visible light spectrum pf electromagnetic radiation.

Question 3

Visual transduction

Answer 3

Photoreceptors (rod cells-black/white, and cone cells-colour) convert electromagnetic energy into electrochemical nerve impulses. Light is transduced in receptive fields, which are areas of the visual field received by particular clusters of photoreceptors which are connected to a single neuron.

Question 4

Visual transmission

Answer 4

Visual information is sent to the visual cortex (occipital lobe) along the optic nerve, via the thalamus.

Question 5

Visual selection

Answer 5

Feature detector neurons in the primary visual cortex select which visual stimuli we pay attention to. They activate when certain attributes are present, breaking down the key parts of the image.

Question 6

Biological influences on visual perception

Answer 6

Physiological makeup: damage or impairment of visual structures (e.g. myopia/hyperopia)
Ageing: associated with poorer vision (e.g. presbyopia, cataracts)
Genetics: many genetic disorders are inherited (e.g. colour-blindness)

Question 6

Visual organisation and interpretation

Answer 6

Images are organised and given meaning through the use of visual perception principles (Gestalt, dept cues, visual constancies)

Question 7

Perceptual set

Answer 7

An individual’s predisposition to view stimulus in a certain way based on past experiences, context, motivation, and emotional state.

Question 8

Gestalt principles

Answer 8

Figure-ground organisation, closure, similarity, proximity

Question 9

Binocular depth cues

Answer 9

• Retinal disparity (disparity between right and left retinal images)
• Convergence (eye muscles turning inwards for closer obejcts)

Question 10

Monocular depth cues

Answer 10

• Accommodation (muscle tension to focus lens)
• Pictorial depth cues (linear perspective, interposition, height in plane, texture gradients, relative size, light and shadow)

Question 11

Hudson 1960

Answer 11

Concluded that 3D interpretation of images was a cultural skill (showed images with pictorial depth cues to people from a village in South Africa vs Caucasians)

Question 12

Deregowski 1972

Answer 12

Concluded that many non-Western people lack pictorial depth perception and prefer split drawings to perspective drawings, likely due to limited experience with depth cues.

Question 13

Deregowski, Muldrow & Muldrow 1972

Answer 13

Concluded that perception was mostly based on the person’s familiarity with the image depicted, although unfamiliar images could be recognised with effort.

Question 14

Muller-Lyer

Answer 14

Two vertical lines with different ends. The one with the feathered tail is perceived as longer than the one with arrow heads. ‘Carpentered world hypothesis’ attributes this to use of linear perspective depth cue. ‘Perceptual compromise theory’ attributes this to the gestalt principle of closure.

Question 15

Ames room

Answer 15

Causes people to perceive false differences in object size. Works due to trapezoidal shape of room (rectangle expected due to perceptual set), viewing of the room with one eye which prevents use of binocular depth cues, and the manipulation of pictorial depth cues.

Question 16

Ponzo visual illusions

Answer 16

Two horizontal lines between converging vertical lines. The upper horizontal line is perceived as longer due to the depth dues of linear perspective and height in plane.

Question 17

Ambiguous figures

Answer 17

Ambiguous figures can be interpreted in multiple ways because they induce multi-stable interpretation, often by manipulating gestalt principles.

Question 18

Impossible figures

Answer 18

Impossible figures are 2D images that generate a 3D perception which would not occur in reality. They manipulate pictorial depth cues so that we perceive apparent depth where it cannot actually exist.