Lecture 4: Colour vision and Perception

Question 1

Trichromatic Vision

Answer 1

Humans possess three types of cones sensitive to different wavelengths of light, allowing for full-colour vision.

Question 2

Cones

Answer 2

Photoreceptor cells in the retina responsible for colour vision. There are three types:
* S (short wavelength): Sensitive to blue light.
* M (medium wavelength): Sensitive to green light.
* L (long wavelength): Sensitive to red light.

Question 3

Mosaic of Cones

Answer 3

The arrangement of cones in the retina, with a high density of red (L) and green (M) cones and fewer blue (S) cones.

Question 4

Monochromats

Answer 4

Individuals with only one type of functioning cone or none at all. They can only perceive lightness and darkness (black-and-white vision).

Question 5

Dichromats

Answer 5

Individuals with two functioning types of cones. They have limited colour discrimination, often unable to distinguish between certain colours (e.g., red-green or blue-yellow deficiencies).

Question 6

Anomalous Trichromats

Answer 6

Individuals with three types of cones, but one type has an altered spectral sensitivity. This results in reduced ability to discriminate between certain colours compared to normal trichromats.

Question 7

Colour Constancy

Answer 7

The ability to perceive the colour of an object consistently under varying lighting conditions by discounting the light source’s influence.

Question 8

Opponent Channels

Answer 8

A mechanism in the retina and brain combining cone signals into channels to process colour:
* Red-green channel
* Blue-yellow channel
* Luminance channel (black-white)

Question 9

Anomaloscope

Answer 9

A tool used to measure colour vision and distinctions.

Question 10

Retinal Processing

Answer 10

The process by which retinal ganglion cells combine signals from cones to create opponent channels.

Question 11

Colour Signal in Health Detection

Answer 11

More oxygenated blood appears redder, acting as a signal of health.

Question 12

Gene Therapy for Colour Vision

Answer 12

Inserting a missing cone’s gene to enable colour vision in species or individuals with colour blindness.

Question 13

Colour Symbolism

Answer 13

The association of colours with specific meanings or cultural affiliations (e.g., red for love, danger).

Question 14

Adaptation in Colour Perception

Answer 14

A phenomenon where prolonged exposure to certain colours results in aftereffects or changes in perception.

Question 15

Cultural Variance in Colour Preferences

Answer 15

Preferences for natural colours like blue and yellow differ between cultures based on ecological and societal factors.

Question 16

Memory Colours

Answer 16

The brain’s tendency to associate certain objects with specific colours, influencing perception even when the object lacks its typical colour.

Question 17

Ecological Theory of Colour Preference

Answer 17

Colour preferences are influenced by associations with natural objects (e.g., blue for clean water, yellow for rotting food).

Question 18

Biological Mechanisms of Colour Preference

Answer 18

Preferences for certain colours are driven by inherent biological processes.

Question 19

Colour Vision and Aging

Answer 19

With age, the lens yellows, reducing the input from S-cones and altering colour perception.

Question 20

Psychophysical Tasks

Answer 20

Experiments to test colour vision, often used in research or therapy assessments.

Question 21

Colour Consistency Mechanisms

Answer 21

Systems in the brain that allow us to perceive stable object colours despite changes in lighting conditions.

Question 22

Regan, Julliot, Simman, Vienot, Charles-Dominique & Mollon (2001)

Answer 22

• Focus: Evolution of cone types in humans and other species.
• Key Findings: Trichromatic vision evolved for detecting ripe fruits and socio-sexual signals.

Question 23

Changizi, Zhang & Shimojo (2006) - Study 1

Answer 23

• Focus: Evolution of cone types.
• Key Findings: Trichromatic vision evolution linked to detecting environmental signals.

Question 24

Changizi, Zhang & Shimojo (2006) - Study 2

Answer 24

• Focus: Socio-sexual signals from blood oxygenation.
• Key Findings: Trichromatic vision detects subtle changes in skin colour for social and mating cues.

Question 25

Mancuso et al. (2009)

Answer 25

• Focus: Gene therapy for colour vision.
• Key Experiment: Enabled squirrel monkeys to see colour via gene therapy.
• Key Findings: Showed potential to correct colour blindness through genetic interventions.

Question 26

Jordan, Deeb, Bosten & Mollon (2010)

Answer 26

• Focus: Genetic and physiological basis of colour vision.
• Key Findings: Genetic variations in cone types impact human colour perception.

Question 27

Hansen, Olkkonen, Walter & Gegenfurtner (2006)

Answer 27

• Focus: Memory colours and top-down effects on colour perception.
• Key Experiment: Objects adjusted to grey overshot towards typical colours due to memory associations.

Question 28

Hurlbert & Ling (2007)

Answer 28

• Theory: Biological Components Theory.
• Focus: Biological mechanisms of colour preferences.
• Key Findings: Colour preferences linked to biological functions like health or danger cues.

Question 29

Palmer & Schloss (2010)

Answer 29

• Theory: Ecological Valence Theory.
• Focus: Colour preferences based on ecological associations.
• Key Findings: Preferences relate to associations (e.g., blue for clean water, yellow for rotting food).

Question 30

Juricevic, Land, Wilkins & Webster (2010)

Answer 30

• Focus: Colour perception and preference.
• Key Findings: Explored discomfort and aesthetic responses to colours; highlighted individual and cultural differences.

Question 31

Maule et al. (2024)

Answer 31

• Focus: Aesthetic preferences for colour patterns.
• Key Findings: Investigated how pattern and colour combinations influence aesthetic responses and how these may vary by context or individual preference.

Question 32

Purves & Lotto (2002)

Answer 32

• Focus: Colour constancy and perception mechanisms.
• Key Findings: Colour is constructed by the brain, not directly perceived.

Question 33

Witzel, Racey & O’Regan (2017)

Answer 33

• Focus: “The Dress” phenomenon and differences in colour perception.
• Key Findings: Demonstrated how assumptions about lighting and context affect individual perceptions of colours in ambiguous images. Showed that differences in perception stem from variations in colour constancy and brain processing preferences.