NATS 1870 Final Exam Review | Based on quizzes from lessons 13-23

NATS 1870 Final Exam Review | Based on quizzes from lessons 13-23 Through accommodation, your eye can change its refractive power to help it focus images by Changing the shape of the lens itself, via attached ciliary muscles contracting or relaxing it (lesson 13) We have blurry vision in water (such as in a swimming pool) because Cornea itself is mostly made of water, reducing the difference in indices of refraction (lesson 13) A person born with no (functioning) retina in his eyes would Be completely blind (lesson 13) Although the eye and camera share the light capturing functionalities in common between them, the eye differs from a camera in another key subsequent functionality known as Transduction (lesson 13) In what sense might we be using colours as symbols? Colours are symbols for different light stimuli (lesson 13) T or f: cones require brighter lighting conditions than rods to function True (lesson 13) Without any blood vessels attached to them, and themselves composed of tightly packaged crystalline fibres, cornea and lens remain Transparent (lesson 13) What was the earliest form of vision like? In black and white only, using rods (lesson 13) Which labelled position in this diagram indicated the location where most of the cones can be found? D (lesson 13) The image below shows an example of one of our important uses of colour. What is it? Distinguishing objects from one another (lesson 13) Out of the following aspects involved in colour vision, which one is considered to be the most known and understood by science? Anatomy of the eye (lesson 13) Which of these three diagrams shows how an image is focused in someone who is near sighted? C (lesson 13) Which parts of the human eye do not contribute to the focusing of the incoming light? All contribute to focusing (all: cornea, aqueous humor, vitreous humor, lens) (lesson 13) The opponent colour system Subtracts cone signals from each other, to distinguish colours (lesson 13) The s, m and l type cones evolved in past organisms at different times in history. Rank their first appearance in chronological order, from oldest to most recent L-s-m (lesson 13) Which of these is not true about the photoreceptors? They are all mostly concentrated at the fovea (true things: there are about 100 million of them in each human eye, they are neural cells, there are no photoreceptors at the blind spot of each eye) (lesson 13) Why are the terms 'pupil dilation' and 'pupil constriction' technically incorrect? It is not the pupil itself that dilates or constricts (lesson 13) Almost all of the refraction of light in the eye is accomplished by which part(s)? Cornea and lens (lesson 13) What would be an advantage for an organism to have trichromatic colour vision over dichromatic? Ability to better distinguish differences between colours (lesson 13) "what colour" is a question that Involves both objective and physical explanations involving light and subjective descriptions of the brain's perceptions (lesson 13) The term 'action potential' is used to describe The passing of an electric signal inside a neural cell (lesson 14) Why is cone vision higher in acuity (sharpness of detail perceived) than rod vision? Due to cones' low convergence, with each single cone connected to a single neuron receiving its signal (lesson 14) How do the bipolar and horizontal cells 'know' that a photon had been absorbed and converted into a neural signal by the photoreceptor cell before them? There is a drop in neurotransmitters being sent to them from the photoreceptor. (lesson 14) As this diagram of the 'electrical wiring' of rods-to-ganglion-cell (red circle) versus cones-to-ganglion-cells shows, 'Rod-vision' is more sensitive than 'cone-vision' since output from multiple rods converges together to trigger a single ganglion cell to fire (lesson 14) According to the dark adaptation curves shown below, how long will it take for our eyes to completely adapt to darkness (after coming into a dark room from the bright outdoors for example)? At least 20 minutes (lesson 14) Each of our 3 types of cone receptors are more sensitive to a different wavelength of light because Each type of cone photo receptors contains a photo pigment molecule with a different absorption spectrum (lesson 14) Due to their initially undeveloped visual acuity, infants Can mostly perceive only images with high bright/dark contrast, and up close (lesson 14) A photon is to light as ____ is to a neural signal? Charged ion (lesson 14) Which of these neural cells in the retina make the immediate contact with the photoreceptor cells at the synaptic layer? Both bipolar and horizontal cells (lesson 14) Neurotransmitters are Molecules sent across a synaptic gap to transmit a neural signal between two separate neurons (lesson 14) The overall photo-transduction of light is achieved by Physical and chemical changes inside the photoreceptor cell (lesson 14) After absorbing an incoming photon, the photopigments (like rhodopsin in the rods) will cause the photoactivation sequence to start, in which Charged ions will be blocked from passing through the cell membrane of the photoreceptors (lesson 14) This diagram of a typical retina section shows that Bipolar cells are usually the first neurons connected to the photo receptors, while ganglion cells are the last ones in this writing network (lesson 14) Retinitis pigmentosa shows that Photoreceptors can 'die' in a person's lifetime (lesson 14) T or f: rods are more sensitive to light than cones True (lesson 14) Which of these is not true about the s-cones? They do not participate in the phototransduction process (true things: they are the fewest in numbers out of all the cone types, they are sensitive to the shortest wavelengths of light, they are virtually missing from the centre of the fovea) (lesson 14) How does the photopigment molecule signal to the rest of the photoreceptor cell that it absorbed a photon of light? By changing its shape (lesson 14) The conversion of light energy into neural (electrical) energy is called Photo transduction (lesson 14) The very first step to 'trigger' (start) the conversion of light into neural signal process is A change in physical shape of the retinal part of the visual pigment molecule (lesson 14) Complete the missing terms in this visual pathway: while our 'seeing' begins in the (a)________, our 'perceiving' of what we're seeing finally occurs in the (b)______. (a) eye; (b) visual cortex (lesson 14) (b) Match the term with its corresponding description, in this sequence summary of the process of our colour perception: (1/3) appearance 'Colour' is consistently assigned to lights and surfaces to generate perception of colours in the world (lesson 15) Match the term with its corresponding description, in this sequence summary of the process of our colour perception: (2/3) discrimination Wavelengths of light are distinguished from each other (lesson 15) Match the term with its corresponding description, in this sequence summary of the process of our colour perception: (3/3) detection Wavelengths of photons of light from the external environment are sensed by internal light sensitive cells in our eyes (lesson 15) Our eyes must be able to adjust to changes in total amount of light entering them by a factor of several billion photons. What is their most efficient mechanism for doing to? Detecting relative differences in detected light levels (lesson 15) Outside during a moonlit night, it is hard for us to distinguish colours in objects because We have only rods functioning in scotopic illumination, which suffer from the principle of univariance (lesson 15 T or f: combining yellow and blue colours will produce the same resulting colour in additive and subtractive colour mixtures False (lesson 15) Cone characteristics: which of these is not true? S cones contribute significantly to light levels detection (true stuff: l and m cones have the largest overlap in spectral sensitivity ranges, s cones have the highest intrinsic sensitivity to light, l cones are the highest in population) (lesson 15) Which of these combinations shows the proper peak sensitivities to light of the three types of cones (s,m,l) in our eyes S: 420-440nm m:535nm l:565nm (lesson 15) Cones vs rods characteristics: which is not true? In daytime, cones provide us with colour vision, while rods provide us black white vision (true stuff: there are many more rods than cones in our eyes, rods are more sensitive to light than cones, rods have a spectral sensitivity range as cones do) (lesson 15) The image shows the firing rates of the three cones in response to three different lights. The firing rates of which cone demonstrate the problem of univariance? Cone m (lesson 15) The image shows an example of metamers, which are Two different light stimuli that create the same response from the photoreceptors (lesson 15) Metamers demonstrate that Our visual (nervous) system 'knows' only what the cones 'tell' it (lesson 15) Most colour spaces used in modern times are 3 dimensional because Perception of colour is a neural phenomenon based on outputs from 3 different cone types (lesson 15) Which of these achievements in advancing the understanding human perception of colour came first, preceding the other by over a century? Realization that perception of unique colours is driven by 3 separate mechanisms in our brain (lesson 15) Based on the population weighted distribution of the 3 separate types of cones, which 'colour' of light is the human eye most sensitive to? Red (lesson 15) What is the problem of univariance? A single type of a photoreceptor cannot properly be distinguish both the wavelength and intensity of light it absorbs (lesson 15) Pupil dilation/constriction is one mechanism for the eye to regulate how much (or little) light is allowed into the eye. Due to this mechanism, how many more photons are entering a fully dilated pupil (at 8mm) compared to a fully constricted pupil (at 2mm)? Fully dilated pupil lets in 16 times more photons than a fully constricted pupil (lesson 15) Scotopic light refers to Dim light (lesson 15) What did s. Shevell (2003) mean in his statement "there is no red in a 700nm light, just as there is no pain in the hooves of a kicking horse"? 'Colour' is the brains response to a specific light stimulus (lesson 15) According to the trichromatic theory of colour vision, a unique colour is perceived based on The unique combination of outputs by three photoreceptors (lesson 15) In trichromacy, how is a unique firing rate signal from ganglion cells achieved? Firing rates from the three cones together produce a unique combination for a unique light (lesson 15) How did young and hemholtz come up with the trichromatic theory of colour perception? By observing and cataloguing humans' colour perceiving experiences (i.e., based on what they described) (lesson 15) People who suffer from achromatopsia show that The final creation of a perception of colour happens in the visual cortex, but is based on the information from the colour opponent cells (lesson 16) If you were to shine a blue flashlight onto a red t-shirt in a dark rook, what colour will you see? Dark t-shirt, with no colour easily discernible (lesson 16) What would we have to to to 'cancel out; the red light in a, as shown in the diagram? Add its opponent colour (green), in the amount of about 20 units on the y axis (lesson 16) How does our brain give us colour perception, based on the information coming from the cones? It takes firing rates from the three cones and feeds them into two 'equations', where the two perceptual colours will be compared against each other, to determine the final colour (lesson 16) Colour opponent cells are neurons along the visual information pathway which record The subtracted signals from the cones (lesson 16) From a mathematical perspective why is it a good idea for our visual system (which is like a big calculator) to look at the differences between cones' signals, rather than compare their individual absolute signals? This makes it easier for us to differentiate lights as different 'colours' (lesson 16) The opponent cells have received the following firing rates from the three cones: r=25, g=12, b=67. Which of the labelled lights in the image do they belong to? (hint: you need to do some calculations here) Light a (lesson 16) Which of the following was not one of the 'flaws' of the trichromatic theory of vision, as identified by hering? The existence of cone cells was not proven (some of the flaws: we seem to have natural oppositely-linked colours, red-green colour deficient people can sometimes still perceive 'yellow', the after-image effect results in the complementary colour seen) (lesson 16) Which of the four labelled lights has the highest brightness? C (lesson 16) If all subtractive mixtures remove wavelengths and reduce the intensity of the resultant reflected light, how can we ever make white paint? We cannot make white paint through mixtures of individual colours (lesson 16) Which of the following three spectral curves, shown in the image, best corresponds to the colours of the final result of the mixture of magenta and yellow lights? A (lesson 16) Which of the following three spectral curves, shown in the image, best corresponds to the final colour of the mixture of magenta and yellow paints? B (lesson 16) An artist is working with 2 mixing palettes, as demonstrated in this image below. On one palette (a), she mixes yellow and magenta paints; on the other palette (b), she mixes yellow and cyan paints. After finishing mixing the paints on the two different palettes, she then points two separate flashes of white light on each palette, such that each flash light hits each palette separately (in the mixture-area), and then reflects at angles such that the two reflected beams of light enter her eyes together, for a magnificent visual experience. What final colour will she perceive? Yellow (lesson 16) What would be the predicted final colour of mixing red and black, according to the additive theory? Red (same as original) (lesson 16) What is the approximate wavelength in the natural em spectrum of light corresponding to the 'purple' colour picked in this colour wheel, as indicated by the arrow in the image: There is no single-wavelength of light corresponding to this type of 'purple' hue (colour). (lesson 16) In the opponent colour theory, a particular colour is perceived Based on the comparison of certain cone output combinations pitted against each other (lesson 16) What do the opponent function curves show, as demonstrated in the image? Colours which our brain 'thinks' are contained in the different wavelengths of light (lesson 16) With the opponent process theory, how can someone with missing m-cones still may be able to see 'yellow'? If activity output rate from the s-cone is lower than from the l cone, the brain will still interpret it as 'yellow' (lesson 16) A unique blue Is light of about 470nm wavelength (which appears to have no red or green in it at all) (lesson 16) In the image, which letter shows the location of the 'unique green' hue? Y (lesson 16) Match the animal with the correct number of different types of cones they have in their visual system: dogs, humans, mantis shrimp, chickens Dogs: 2 humans: 3 mantis shrimp: 12 chickens: 4 (lesson 17) Afterimages happen because Fatigued opponent cells are responding to cones' output slower than they should (lesson 17) Which of these is not a result or insight obtained from studies of animals' colour vision? Humans have the largest number of different types of cones present in their eyes (some results or insights: colour constancy is needed by visual systems of all animals capable of colour perception, perception of colour from lights is a mental process - rather than only a physical property tied to objects - for all animals not just humans, animals can see the world differently from us (in terms of perceived colours) but can still discriminate different wavelengths of light) (lesson 17) To accomplish its main goal, our visual system has been trained to make certain assumptions in the visual scene about Both the nature of surfaces and the nature of the illuminant (lesson 17) The capgras delusion cases of brain damage to the visual system show that in order for us to not only 'see' faces of people we know, but also consciously 'recognize' them, Faces that we see must also be followed with the correct associated emotional response (lesson 17) Colour constancy is possible because Our visual system has learned to make certain assumptions when viewing an image, even if they are not always true (always 17) Which of the following statements best describes the human experience we call 'colour' Colour is the brains response to a physical stimulus (light) (lesson 17) Cultural relativism suggests that There may be some link between cultural descriptions of colours and perceptual experiences with them (lesson 17) The fact that the colour of the 'background' columns does not appear to change significantly under the dark diagonal stripe in the left image, while it does appear to change in the dark diagonal stripe in the right image is a cue ('hint') to the visual system that The dark stripe in left image is a shadow, while the dark stripe is made of different-coloured patches in the right image. Colour - for example 'red' - belongs to The brain mapping a consistent neural response to a certain light stimulus (lesson 17) A person who has only the l-cones functioning looks at a red light. What would he see? Light of certain brightness, but no colour to it (lesson 17) When we look at objects, what is the main goal of the visual system to determine? The reflectance properties of the object itself (its colour) Which of the following is not one of the assumptions the visual system has been trained to make? White surfaces reflect 100% of incident light, while black surfaces absorb 100% of incident light (true assumptions: natural light sources are usually 'broadband', sharp borders with colour changes usually belong to physically differently-coloured surfaces, physical surfaces' reflectances are usually broadband) (lesson 17) Grey and brown are examples of related colours, which means that Our perception of them depends on other colours nearby (lesson 17) Which of the following statements belongs to a synesthete? 'The number 2 is red' The dark stripe in left image is a shadow, while the dark stripe is made of different-coloured patches in the right image. Yes (lesson 17) Generally speaking, colour vision in animals allows them to distinguish colours in nature that appear to help with All: identifying possible predators more quickly in their environments attracting healthier mates for reproduction finding safe food to eat (lesson 17) If colour is a subjective and individual experience, then how can we know what 'normal' colour vision is like? We can ask large numbers of people to do colour-matching experiments, to create a consistent catalogue/system (lesson 17) The image shows three examples of a 'white-ish' illuminants' light curves, demonstrating that Despite all three appearing generally-white, they each contain different spectral power distributions (lesson 17) Thanks to colour constancy, a yellow banana Will appear yellow under a wide range of illuminants (lesson 17) The light-dark contrast, when applied to colours (hues) as in the brightness- only version of the original colour figure 12 (shown in the image) shows that Different hues have intrinsically different brightness levels (lesson 18) Cold and warm colours May have some link to the apparent temperature experienced by people (lesson 18) What are the complementary colours? Two colours which, when mixed together, will produce some neutral shade of grey (for paints) (lesson 18) Contrast of extension is based on the idea that Different colours should be used in different proportions to achieve a balanced image (lesson 18) If you were truly colour blind, then which of the 7 types of colour contrasts would you still be able to perceive, in the image shown? Brightness and extension (lesson 18) In the image, which of the following colour contrasts are present? Both 'light-dark' and 'extension' Which of these contrasts of colours is the hardest to notice or distinguish? Simultaneous (lesson 18) Which of the following statements about non-spectral purples is correct? The colour purple does not exist as a single dominant wavelength in the em spectrum (lesson 18) Which of these is not an example of a contrast? Mostly grey surfaces (actual examples of contrast: black and grey surfaces, black and white surfaces, white and grey surfaces) (lesson 18) When black is placed next to other 'colours' in an image, what is the overall effect on these colours? The colours will appear brighter (lesson 18) Which of the spectral reflectance curves shown here corresponds to the most saturated green paint? D (lesson 18) Referring to the spectral reflectance curves shown in the image, which of these corresponds to the brightest green paint? A (lesson 18) To which physical parameter of 'colour' below can 'saturation' be most closely related to? Amount of pure hue present (lesson 18) The simultaneous contrast is similar (at least from the physiological perspective) to which phenomena? Afterimages (lesson 18) Which of these colour combinations present the strongest contrast of hue? Red, blue, yellow (lesson 18) Rank these colour swatches (image) in order of increasing brightness: C-b-a Rank these colour swatches (image) in order of increasing saturation C-a-b (lesson 18) Rank the three swatches on the right in order of increasing saturation This exercise cannot be done (lesson 18) The first row of the image shows original hues; the second shows the same hues but as either tints or shades. Which of these are tints? A, c, e (lesson 18)