Adaptation Research

Adaptation is the process of the receptors becoming less sensitive as a result of continued presentation of the same stimulus (Davis, & Palladino 2007). In other words the receptors “get use” or adjust to the brightness of a light or the darkness of a room, depending on the surrounding we are in. For instance, if you are in a suddenly darkened room your eyes will adjust to the darkness and be able to see around the room after you stand in it a few minutes. This works with all of the five sensory receptors found in the eyes, ears, mouth, nose, and skin. Below, I have conducted three different experiments in which adaptation occurs, and I will explain how each was done and how adaptation is evident in each one.

The first experiment I chose to undertake was the sandpaper test. The experiment instructs me to rub my finger across a rough piece of sandpaper, and rate its coarseness on a numbered scale. Next, I am to wait a minute or two, and then rub the same finger across the same sandpaper and rate its coarseness again a second time. On a scale from 1 to 7 (1 being soft and 7 being rough), the sandpaper was rated at a 7 when I first rubbed it. The second time I rubbed the same sandpaper I rated the roughness at a 5. So the feel of the sandpaper felt smoother on the second rub. I found that my perception of the sandpaper’s coarseness changed after the repeated action of rubbing the same finger for the second time. The conclusion; the skin on my finger adapted to the coarseness of the sandpaper because of the repeated exposure to the same stimulus. In order for my finger to send the signal of the feel of the sandpaper to my brain for processing, my skin must be filled with cutaneous receptors that pick up on sensations such as touch, temperature, pain, and pressure on the skin. Once the cutaneous information has been sensed by the machorecptors by either fine hair movement on the skin, or by dents in the skin being stimulated, the information travels through sensory nerves all the way up the spinal cord and synapse in the thalamus. From there the information is correlated over to the somatosensory cortex in the brain for further analyzing (Davis, & Palladino 2007).

The second experiment I conducted was to fill up two cups of water: one with sugar water, and one with none. I will first sip the cup containing the sugar water and swish the liquid around my mouth momentarily before swallowing. Then, I will taste from the cup that contains the fresh water. This is what I experienced while performing the experiment; when sipping from the cup of fresh water, I was surprised because I expected the water to taste sweet after drinking form the sweetened cup. Instead the water ended up tasting every bland to me. I would have never had expected fresh water to taste bad. In the past, whenever I have drank regular fresh water, the water never had much taste to it at all, neither good or bad, but in this instance, it seemed to be very bland tasting to me. I can only assume this happened because my taste buds had adapted to the sweetened water very quickly, so when I immediately switched back to drinking the none flavored drink, it tasted very bland because of the fact that the taste buds had already adjusted to the taste of sweetness. My perception of how water should taste changed rather quickly! The stimuli used to determine taste are molecules dissolved in fluid form. When the liquid is drunk it comes into contact with taste buds that are located on the tongue, sides of the mouth, roof of the mouth, and in the back of the throat (Davis, & Palladino 2007). These taste buds are filled with taste receptors cells. How exactly does the taste receptor cell carry out the message of taste? One theory suggests that the molecules in the liquid attach to or fit into receptor sites which are tiny microscopic hairs called microvilli. “The receptor sites have different geometric shapes, so the shape of the molecule determines whether it fits into a specific receptor site” (Davis, & Palladino 2007). The theory also suggests that each shape determines what flavor we perceive such as sweet, salty, bitter, and sour. There are at least for different shapes representing each flavor, maybe even more. Once a molecule is fitted into the right receptor site, depolarization occurs and information is sent through the gustatory nerve into the brain.