~Chapter 9 - Lecture Section 9.1 Flashcards
True or False: Homo Sapiens type of colour-vision is fairly rare among mammals
True. The colour-vision that we enjoy is actually fairly rare among mammals.
What are the proposed theories about why primates developed colour-vision?
It has been proposed that primates developed colour-vision due to their arboreal ecology. Another proposal is that good colour-vision can compensate for the poor sense of smell that primates have.
What type of colour-vision do most mammals have?
Other mammals are typically Dichromatic
What animals sometimes have more than 3 Cones?
Birds and lizards have sometimes more than 3 cones
There is an ___ to having colour information. It creates a very vivid use of colour during visual perception.
evolutionary advantage
Why is it an evolutionary advantage to have colour information?
A Rod Monochromat, meaning they have no colour signals at all, would have a lot of trouble foraging for ripe berries and fruit.
Colour is important for our ___ when we consider studies that look at the accuracy and speed of ___ objects if they were appropriately or inappropriately coloured.
object processing // naming
Who initially described light?
Newton initially described light with his prismic experiments, where he proposed that white light is made up of different “particles” (wavelengths). This was later revised to light being composed of different wavelengths, or acting as these photons.
How did Newton prove his theory on colour?
When passing white light through a small aperture, such that it entered a prism, Newton showed that the white light could be separated into these constituent wavelengths, and when he isolated these wavelengths individually, he noted that it couldn’t be divided anymore.
And so he proposed that white light was composed of all these different wavelengths, and that these long wavelengths show less refraction, that is to say, less bending when they go through a prism, than the short wavelengths.
Long Wavelengths show ___ refraction, that is to say, ___ bending when they go through a prism
less // less
What is Reflectance?
Reflectance is the amount of incident light that is reflected off the object
The percentage of light reflected from a surface.
When there is Incident Light, light shining from some light source, there will be ___ off of an object.
Reflectance
Coloured objects exhibit ___ due to the molecular structure of the material that they’re made out of.
selective Reflectance
Coloured objects exhibit ___ due to the molecular structure of the material that they’re made out of.
Selective Reflectance
A white piece of paper reflects all wavelengths ___, so we have white incident light, and all wavelengths are reflected more or less equally to our eye so this paper will appear light.
equally
A red piece of paper, from white incident light, absorbs the ___ wavelengths of light and selectively reflects ___ wavelengths of light, the absorbed wavelengths of light are turned into heat
shorter // long
What is Selective Transmission?
Allow only select Wavelengths to pass through
When some wavelengths pass through visually transparent objects or substances and others do not. Selective transmission is associated with the perception of chromatic color.
Where does Selective Transmission occur?
See-through items such as glass or liquids
What is Selective Reflection?
When an object reflects some wavelengths of the spectrum more than others.
How would light react to a red glass of cranberry juice
There is Selective Transmission, only the red wavelengths can pass through it, where the other wavelengths are absorbed. Instead of Selectively Reflecting long wavelengths to appear red as a solid object would, these transparent liquids and glass will allow certain wavelengths to pass through while absorbing other wavelengths.
Reflectance Curves are useful when talking about the visual stimuli and the responses of ___.
photoreceptors
How is Reflectance Curve measured?
A plot showing the percentage of light reflected from an object versus wavelength.
In a Reflectance Curve, coloured objects will have a ___ in the reflectance curve.
peak
What is the reflectance of green Lettuce?
For green lettuce, there is some reflectance at these low and higher wavelengths, but it peaks at the middle, and so that is why we see it as green.
What is the reflectance of a Tomato?
For a tomato, the peak is over in the long wavelengths, and so we see it as red.
Items that have ___ are seen as black, grey, or white.
Flat Reflectance Curves
___ paper absorbs most incident light, and so it has very ___ reflectance.
Black // little
___ paper reflects most of the incident light, and so it has ___ reflectance across all wavelengths and it is very high.
White // equal
What is the reflectance of Grey?
Grey, depending on how dark the gray is, is going to be in the middle.
What do you get when you mix yellow and blue paints?
Blue + Yellow = Green paint
