Case Study: Some background: A two-point threshold on the skin is found by taking two points (for example, the tips of two pens) and pressing them both against your skin close together, and then moving the two points apart until you can detect that two different points are touching your arm. When you first put the points close together, they will be felt as one point, the distance between the pens when you feel them as two different points is the two-point threshold. It will likely work best to have someone feel for points, and someone else do the pointing and measuring of the distances between points. [It will help to have a ruler]

Question 1.. Write a brief definition of "receptive field".

Question 2.. Do you think the two-point threshold for seeing is likely to be greater or lesser than for skin? Why?

Question 3..For the skin`s two-point threshold do you think it will matter if the person being tested looks at the two pens while being tested? Why? How might looking change sensitivity? How might it change bias?

Question 4.. Measure the skin two-point threshold for a fingertip. Next, measure the two-point threshold for the back of an arm. How far apart do the points need to be on the two parts of your body?

Question 5.. Are the thresholds for the tip of the finger and arm different? Why? Be sure to provide both a mechanistic answer and a functional answer. For the mechanistic answer to why, make an educated guess whether the arm is a converging or linear circuit and whether your finger is a converging or linear circuit (in your answer be sure to clearly define both types of circuits). For the functional answer think about what the two parts of the body do and why they would need to feel one or two things. Be sure to explain your reasoning behind your educated guesses.

Question 6.. It is important for you to know the relationship between the mechanism and function for the rods and cones. List the differences between rods and Cones in mechanism and function. Choose one functional difference and explain how it is related to mechanistic difference(s) (note, likely several mechanistic differences will be relevant).