WK2

• What is the distinction between sensation and perception?


  Sensation refers to qualities of visual experience, while perception is sensory knowledge about properties of the world.
• What are colours considered to be in terms of sensory experience?


  Colours are considered qualities of sensory (visual) experience, or sensations.
• How are sensations related to information about the world?

  Sensations are the way in which information about the world is presented as conscious experience.
• How does the experience of holding a red book illustrate the concept of sensation?


  Holding a red book evokes tactile sensations related to its physical properties, such as warmth or coolness.
• What is the Trichromatic theory of colour vision also known as?


  Trichromacy theory
• What is the relationship between visual sensations and the properties of objects?


  Visual sensations, like the book's redness, are perceived as properties of the object itself.
• What does the Trichromatic theory explain about colour vision?


  It explains how we see colours based on three types of photoreceptors involved
• What is the challenge in identifying the physical characteristic related to colour?


  Identifying the physical characteristic related to colour is complex and difficult to answer properly at this stage.
• Who formulated the Trichromatic theory?


  Helmholtz
• What does colour vision enable animals to do?


  Colour vision enables animals to distinguish between similar appearances and locate items more quickly.
• On whose earlier ideas was the Trichromatic theory based?


  Thomas Young
• What are the two main functions of colour vision illustrated in the examples?


  • Distinguishing between similar items (e.g., ripe vs. unripe raspberries)
  • Locating items quickly (e.g., finding blue flowers in a field)
• What is the basis of what people learn about colour vision in school?

  Trichromacy theory
• How does colour relate to light?

  Colour is closely related to light, as different wavelengths of light evoke different colour sensations.
• What did Isaac Newton suggest about rays and colours in his work "Opticks"?


  Newton suggested that different rays create vibrations of various sizes that excite sensations of different colours.
• What is the sensitivity of the L-cone for 635 nm light?


  25% of its maximum sensitivity
• What do the pictures suggest about white light and colours?


  The pictures suggest that white is a mixture of all wavelengths and that colours are individual wavelengths.
• Are colours wavelengths of light?


  No, colours are sensations evoked by light stimulation, not wavelengths themselves.
• What two factors determine how the cone responds to light?

  The wavelength(s) of stimulating light and the amount of light
• Why is the idea that different colours are sensations evoked by particular wavelengths considered wrong?


  This idea is wrong because many colours are missing from the rainbow and due to the three colour mixing principle.
• If the response is proportional to the sensitivity for a particular amount of light, what can be assumed about the response?


  The response will vary based on the wavelength of light
• What are non-spectral colours?


  Non-spectral colours are colours that cannot be evoked by stimulation with particular wavelengths, only by mixtures of wavelengths.
• What is the three colour mixing principle?


  The three colour mixing principle states that any colour can be produced by mixing just three primary colours in appropriate proportions.
• What does it mean for a light to look the same colour in terms of metamers?


  It means it evokes the same response pattern from the cones
• What are primaries in the context of colour vision?


  Primaries are basic stimuli that evoke particular colour sensations when presented in isolation.
• What is the significance of the three types of cone photoreceptors in our eyes?


  The three types of cone photoreceptors respond differently to wavelengths of light in the visible range.
• What are the important points regarding cone responses and colour perception?


  1. Different cones are sensitive to different wavelengths.
  2. Cone response depends on the wavelengths and amount of light.
  3. Metamers exist because different lights can evoke the same cone response.
  4. The response pattern can be described in ratios, affecting perceived colour.
  5. Perceived colour is determined by the response pattern in the three cones.
• How is perceived colour determined according to the Trichromatic theory?


  By the response pattern in the three types of cones
• How do the three types of cones differ in terms of their absorption of light?


  The three types of cones have different opsins that absorb light differently across the visible spectrum.
• What are the three types of photoreceptors involved in colour vision?

  1. L-cone, M-cone, and S-cone
• What is the significance of the distribution of cone types across the retina?


  There must be roughly equal numbers of each type distributed evenly
• Why are cones no longer referred to as red, green, and blue cones?

  Cones are referred to as long wave sensitive (L-cones), middle wave sensitive (M-cones), and short wave sensitive (S-cones) because their peak sensitivity does not correspond to red, green, and blue.
• What are the key aspects of the Trichromatic theory?


  1. Three types of photoreceptors contribute to colour vision.
  2. They have broad, overlapping spectral sensitivities.
  3. Equal numbers of cones are distributed evenly across the retina.
  4. The response pattern determines perceived colour.
• What is the Trichromatic Theory of Colour Vision?


  • Proposes that we possess three types of colour-sensitive mechanisms in our eyes.
  • Each type of cone responds to different wavelengths of light.
  • Explains how we perceive a wide range of colours.
• How has the Trichromatic theory influenced public understanding of colour vision?


  It has dominated thinking for nearly 170 years and influences education
• Does the Trichromatic theory explain all facts concerning colour perception?


  No, it raises questions about its completeness and accuracy