Question

Do a study of the two-point threshold. Have a friend take a pair of scissors and, with the blades closed, touch you lightly on the forearm with the points while your eyes are closed. Have your friend open the blades slightly and touch you with both points at the same time. Have your friend continue to spread the blades and touch you just to the point at which you can feel both blades. Now measure the distance between the points of the scissor blades. This is the two-point threshold. Repeat this procedure for different parts of your body (e.g., finger, palm, neck, back, foot, thigh). Record your measurements of the two-point thresholds for each body part. Thinking carefully about what you have learned about the brain in this experiment, write up your results and try to explain them. (Note: You do not need to know anything about touch sensation to write this essay.) Be sure to address the following questions: Does the two-point threshold differ across your body? Report your actual measurements of the two-point threshold and use those measurements as the basis of your discussion. Given what you know about the brain, why might the differences that you found exist? Imagine that you had suffered damage to some specific part of your cerebral cortex. Would your ability to detect touches on your skin be impaired? Might this depend on which part(s) of your cortex had been damaged? Explain. Why do you think certain body parts might be "overrepresented" in the human cortex? (Hint: One way to think about this question is to consider why having certain parts of the body be overrepresented in the brain might be adaptive? What in human experience could have lead those parts to be overrepresented?)

Answer 1