Issues to consider in your report:

(1) In the Introduction, outline why it is important to measure the sensitivity of the visual system and what the difference is between the standard measures used by most optometrists and the contrast sensitivity function. What extra information does the latter give? Also discuss any other issues (practical uses of the CSF, changes with age etc)

(2) Results: You will be able to keep a copy of your own results, but for the purposes of data to analyse, you will be given the raw data already obtained from a sample of N=10 subjects.There are two sets of t-tests you should do.

(a) If you look up real data that people have collected under controlled laboratory conditions, you will see that the peak sensitivity which is obtained at 1 cycle per degree is of the order of 100. Do a one sample t-test to test whether the obtained sample mean at 1 cycle per degree is different from 100. This will help you to answer Discussion points (a) and (b).

(b) The shape of the CSF is such that the sensitivities at 0.5 and 1.0 cycles per degree are higher than those at 0.063 and 8 cycles per degree. Use dependent sample t-tests to test whether the mean sensitivities at 0.063 and 0.5 are different; and whether the sensitivities at 1.0 and 8.0 are different. This will help you draw some limited conclusions about the shape of the measured CSF.

(3) In the Discussion consider the following:

(a) Did the arcade game allow you to obtain a reasonably good measure of the CSF? How did the measure obtained differ from that usually obtained in the laboratory (see graphs of the CSF in textbooks or journal articles).

(b) What differences in method are there between the measures you obtained and those which might normally be used in the lab? How might these account for the differences you have pointed out in (a)? How might you change conditions but still use the game to obtain measures more like those normally obtained in the lab?

(c) Consider the three classical behavioural (psychophysical) methods proposed by Fechner (see exerpts from Sekuler and Blake's book, p. 490-493). Does the method used in your arcade game experiment resemble any of these? Which one(s)?

(d) Sekuler and Blake tell you that different species have different CSFs - different species are most sensitive to different spatial frequencies. Can you think why that might be the case?