Receptor Processes and Perception

1 page long per question. textbook pdf file attached below.
1. When using the Method of Limits to measure a threshold, the crossover point between detecting vs. not-detecting a threshold may be different for ascending and descending trials. Why do you think this happens? Researchers usually average together the results of ascending and descending trials. Do you think this is valid?2. Does it make sense to separately define the absolute threshold and difference threshold? Can you see how they might be the same?3. Traditionally, the bridges of submarines were illuminated with red light, especially during nighttime operations. Given your knowledge of scotopic vision, why do you think this was done?4. When vision loss occurs in adulthood, there are various ways to restore function. However, restoration does not require that patients learn how to see all over again, as noted in the textbook’s description of the Argus II device. However, in some parts of the world, children born with cataracts may not have access to treatment until they are teenagers, or older. These children do have to learn how to see. What do you think accounts for this difference in response to treatment?5. The book mentions the classic idea of there being only five senses, but also shows that this idea is false. Table 1.1 lists 12 total senses instead. So, why do you think the popular idea of five senses has persisted? In thinking about this, consider on what basis does one define a sense? Following this line of thought, can you list any sense not included in Table 1.1?5. Imagine seeing the letter R. A top-down approach to letter recognition would suggest that you have some knowledge of what the letter R should look like, and this knowledge is used to enable recognition. But think about all of the variations in the letter R – not just in computer fonts but also the endless variety of human handwriting. How does our knowledge of what an R should look like compare to the variety of letters we encounter? How does this knowledge enable recognition when the seen letter is not exactly the same as the mental representation of R? Is it possible to store every possible variation? How can this problem be solved? Include in your answer some (at least four) of the more extreme forms of the letter “R” that can still be recognized as the letter “R” in the proper context.6. In Chapter 3, the Purkinje shift was discussed in relation to the transition from photopic (cone) vision to scotopic (rod) vision during dark adaptation. This phenomenon is associated with, in dim illumination, objects reflecting long wavelength light to appear darker than objects reflecting short wavelength light. Using the information presented in Figure 6.13, can you explain why this is so?7. The most recent evolutionary change to colour vision was the L-cone system, completing the trichromatic system by adding the ability to discriminate the longer wavelengths from the short and middle wavelengths. Further, trichromacy occurs almost exclusively in primates. What do you think might be the evolutionary advantage of this adaptation?