Neurosensation: Colour Vision

Match the descriptions with the correct terms.

Which wavelength is the blue cone most sensitive to, based on this image?

The blue cone is most sensitive to wavelengths around 450 nm, typically associated with blue light.

Which cones does yellow light affect the most?

The yellow light is primarily perceived by the red and green cones, as they respond more strongly to those wavelengths. This only happens if your red and green cones are hyperpolarized.

What are spectral colours?

Rainbow colours made when light is split apart.

What are extraspectral colours?

A mixture of different wavelengths. For example, we see purple when 2 or more wavelengths affect red and blue cones more than green cones.

How does this equation express the ganglion cell colour signal (R-G)?

Ganglion cells are excited by red light and are inhibited by green light.

How does this equation express the ganglion cell colour signal (G-R)?

Ganglion cells are excited by green light and are inhibited by red light.

Explain how ganglion cells are excited by this equation: B-(R+G).

Ganglion cells are excited by blue light and are inhibited by a combination of red and green light (yellow light)

Explain the effects of opponent channels after staring at this image.

Your G-R cells will become less responsive, and your R-G cells will become more responsive; the same goes for B-(R+G) channels, leading to an afterimage effect in complementary colours.

What is the most common component of green-red colour blindness?

The most common component is a deficiency in the green photopigment, leading to difficulty distinguishing between red and green colours.

Explain the colour blindness inheritance in daughters.

Women typically have two X chromosomes. They would need both Xs to carry the faulty gene to be colour blind. If only one X is affected, the other usually compensates, resulting in normal colour vision.

Explain the colour blindness inheritance in sons.

Sons have only one X chromosome inherited from their mother. If that X carries the faulty gene for colour blindness, they will express the condition, as there is no corresponding allele on the Y chromosome to compensate.

The green banana in this photo…

reflects green light than any other wavelength; it absorbs others.

The yellow banana in this photo…

reflects yellow light more than any other wavelength; it absorbs others.

Explain what happens if you put a ripe banana under greenish light.

The banana’s reflectance doesn’t change, but it now sends green light to our eyes. This is th process of colour constancy.

Explain the process of colour constancy from this image.

You can correctly see the blue squares under yellow light in the left picture and can correctly see the yellow squares under blue light in the right picture due to the brain's ability to adjust perception based on surrounding light conditions. Both facets are the same combinations of wavelengths under the same image.

Explain the process of colour constancy when the blue and yellow facet is placed in a white background.

Both facets send a mixture of grey wavelengths to the eye. Our brain interprets them as blue and yellow, respectively, due to the surrounding white light, allowing for consistent colour perception.

From this image, explain how colour constancy could give rise to illusions.

From the image on top, the brain compares to the surrounding area, making it light. From the image on the bottom, the brain is compared to the surrounding area, making it appear darker.

From this image, explain how colour constancy could give rise to illusions.

From the image on top, the brain compares the surrounding area, making it more blue. From the image at the bottom, the brain compares the surrounding area, making it appear purple-ish/pink.

From this image, explain how colour constancy could give rise to illusions.

From the image on top, the brain compares the surrounding area, making it less saturated. From the image at the bottom, the brain compares the surrounding area, making it appear more saturated.