Adaptation as defined in the text is a process by which a continued presence of a certain stimulus causes the receptors to become less sensitive to that particular stimulus. Therefore a stronger stimulus is required to activate the receptors (Davis, S. & Palladino, J. (2007). The stimulation or activation of these receptors is called sensation. The body’s receptors for each of the sensory systems can only respond to one type of environmental stimulus at a time (Davis, S. & Palladino, J. (2007).
There are five major senses that the mind and body utilizes; vision, hearing, taste, smell, and touch. The three experiments that I conducted related to the senses of touch and taste. The kind of adaptation that my receptors processed is sensory adaptation which is due to fatigue or recovery of the receptors. Perceptual adaptation, which is the reticular system of directing the focus of our attention elsewhere, was not one of the experiments that I conducted.
The first experiment I conducted was the rubbing of my index finger over a piece of very coarse sandpaper and rating its coarseness on a scale of 1 (very soft) to 7 (very coarse). The first time I rubbed my finger over the sandpaper I rated the coarseness a 7. After a minute I rubbed the same finger over the sandpaper again and rated it a 6. I did it a third time and rated it a 5. What happened here is sensory adaptation in the sense of touch. As I rubbed my finger over the sandpaper the sensory receptors in my finger registered the coarseness and sent the signal to my brain. The second and third time I rubbed my finger over the paper, my receptors were already adapting to the stimulus and the feeling of coarseness was less.
The second experiment I conducted was to fill 3 medium sized bowls with (1) very hot water, (2) very cold water and (3) a mixture of the cold and hot water. I placed them so my right hand would be placed in the cold water, my left hand would be placed in the hot water and the third bowl of lukewarm water was placed in the middle. I placed each hand into their respective bowls for approximately 3 minutes. After three minutes, I removed each of my hands from the bowls and placed both hands in the lukewarm water. When I placed my hands into the lukewarm water each hand felt the water at a different temperature. My right hand, which was in the cold water, felt the lukewarm water to be hot and my left hand, which was in the hot water, felt the lukewarm water to be cold. What happened here is that my hands sensory receptors had adapted to the temperature of each of the cold and hot water bowls and when placed together in the lukewarm water, the receptors were still sensing the hot and cold water. The receptors then felt the lukewarm water at different temperatures because they were compensating for the temperature of the water they had just left.
The third experiment I conducted was filling one cup with sugar water and one cup with fresh water. I took a sip of the sugar water and swished it around my mouth for approximately one minute and spit the water out. I then took a taste of the fresh water. The fresh water tasted cold, crisp and refreshing. The reason for this is that the taste receptors in my mouth are sensitive to four primary tastes, sweet, sour, bitter and salty. By taking the sweet water first, my taste receptors were sending the signal of sweetness to the somatosensory cortex in the forebrain by way of the medulla and thalamus. The reason the fresh water tasted crisper and more refreshing is that the taste receptors were busy sending the sweet signal to my brain. The fresh water has no taste so the receptors were not trying to detect a new taste therefore they lay in wait for a new taste sense to send. The fresh water was also colder because there weren’t any other tastes in the water to detract from the senses of cold and hot.
Molecules in solutions stimulate taste and taste buds are the receptors. Receptors can respond to several tastes but each one is maximally sensitive to one of the four tastes mentioned above. The process by which the receptors send the energy they receive to the nervous system is called transduction. These processes are demonstrated through the three experiments I conducted.
References
Davis, S. & Palladino, J. (2007). Psychology. 5th Ed. Pearson Prentice Hall.
