Sensory adaptation: mechanisms and perceptual effects

Psychology

Sensory Adaptation

This report is a summary of the three of four experiments required for this assignment. The objective of the experiments was to test and also demonstrate how the human body has the ability to adapt in certain experiences. This sensory adjustment is known as 'sensory adaptation.' Each of these experiments was designed to be easy to perform but still is more than capable of providing proof that the human body is in fact making minor adjustments so as not to overload itself in its environment.

This report therefore defines sensory adaptation and describes the systems of the body that receive sensory information. The three experiments were:

Rub your index fingers gently over a piece of very coarse sandpaper

Take about 15 index cards and a flashlight that is opaque on all sides into a very dark room

Fill 3 medium-sized bowls separately with hot, cold and a mixture of hot and water

The three experiments test sensory adaptation. Sensory adaptation is basically a change in the sensitivity to a particular stimulus as a result of being exposed to that stimulus. In other words, the body is making adjustments because it has seen or touched this or that scenario before. There are many examples of the body making adaptive adjustments. Some examples include our ability to adapt to darkness or light, hot or cold weather, and different smells to name just a few.

These abilities to adapt are most likely left over from our early ancestors who were more closely tied to the world of mammals and a constant struggle for survival. In order to survive the human body evolved. This evolution required our ancestors to be able stay alert for the next danger so the body could not be preoccupied. For example, the aroma of a beautiful flower should not preoccupy us as a tiger is about to leap.

Experiment 1 consisted of my having to gently rub my index finger a few times over a piece of very coarse sandpaper. After that I had to rate its coarseness on a scale from 1 which was very soft to 7 which was very coarse. After a few minutes I repeated the experiment once again rating the coarseness by the same scale. The results surprised me. The first time I rubbed the sandpaper the coarseness rating was a definite 7. but, the second time around the sandpaper did feel different. I scored it a 3 the second time around.

The second experiment had me take 15 index cards and a flashlight that was opaque on all sides into a dark room. The objective then was to place all of the cards over the light beam. Then I was to slowly remove one card at a time until I could detect light. When light was detected I had to count the cards that stayed over the light. In my case there were 6 cards left over the light. After waiting a few more minutes, I thought that the light was getting more obvious so the experiment required me to begin adding cards back over the ones already on the flashlight. Although I did not get back to all 15 cards, I was able to see the light more easily the longer I was in the dark room even as I was adding cards back over the light.

The third experiment required that I fill 3 bowls with water. The first bowl was to be filled with very hot water, the second very cold water, and the third with a mixture of hot and cold. I then had to put the bowls so that my right hand was in front of the cold bowl, my left hand was in front of the hot bowl and the warm bowl was in between them. I then put my hands, right in the cold and left in the hot, and after around three minutes I put them in the warm bowl. The results were again surprising. The hot and cold seemed very hot at first but then as I got used to the temperature they began to not be too bad. When I put both hands in the warm bowl, the hot hand seemed warm and the cold hand seemed cool.