In 2004, Sarah Thomas, an undergraduate student at Portland State University, completed an experiment to determine the effect of biofeedback training on muscle tension and skin temperature. The purpose of this experiment was to train the subject of the experiment to change their decrease muscle tension and increase skin temperatures in response to tones. The experiment was based on the research done by Miller and Bruckner in 1979. The experiment done by Miller and Brucker dealt with how rats can modify their heartbeats when given pleasurable brain stimulation (Lee, 2014).
The same premises were used in this experiment to see if humans can adjust their muscle tension and skin temperature as a cause of stimulations. The results found in this lab report claim a correlation between a positive reinforcement and control of one’s body, but these results are invalid due to the low sample size and lack of diversity in subjects. Thomas used seven different subjects in their 20’s, five women and two men, for this experiment. She used a thermode to measure the change in skin temperature of the index finger and used electrodes to measure the muscle tension of the frontalis muscle.
The first part of the experiment dealt with the changes in muscle tension of the frontalis muscle. The frontalis muscle is the muscle of the forehead and controls minor movements in the eyebrow and sometimes eyelid. Even small movements such as looking up or moving your eyebrow up affects the muscle tension in the frontalis muscle (Frontal, 2001). Three electrodes were placed on the frontalis muscle after the forehead had been wiped with an alcohol pad. It began with a 90 second trial to hold as a control to compare the rest of the ata to.
The subjects were told to relax their muscles and were told that if they heard a tone, they had reached their goal. The tone rang when the muscle tension was lower than the mean of the last trial and served as a reward system. The second part of the experiment dealt with changes in skin temperature. The same style of experiment was done where if the temperature increased above the mean of the last trial a tone would beep. The second part of the experiment also utilized 90 second trials.
The results of the experiment showed that all seven subjects in the experiment were able to increase their skin temperatures and decrease their muscle tension in at least one of the two sessions. The only major deviation from the rest of the data was subject seven. Subject seven had an overall average of mean skin temp minus baseline as a negative when the rest of the data was positive. Regardless, the data collected allowed Thomas to conclude that operant conditioning could be used on humans to train them to decrease muscle tension and to increase skin temperature.
Operant conditioning is a theory formulated by B. F. Skinner in the 1920s that taught positive reinforcement of an action would foster encouragement for the action to be done again. On the other hand, negative reinforcement of an action would foster resistance to do the action again (McLeod, 2007). Thomas uses this theory to set up her experiment. She views the tone as a positive reinforcement to teach the subject to repeat the action of increasing skin temperature or decreasing muscle tension.
Thomas’s lab and lab report did certain things effectively, but there were also many things that could be improved on. One thing she did effectively in the experiment was cleaning the forehead with alcohol. This allowed the data on muscle tension to be unaffected by dirt or any other contaminant. Another thing she did effectively in the experiment was use the tone as a positive reinforcement to show the subject that they were doing something right. This allowed the subjects either subconsciously or consciously to respond and continue to that action.
In her lab report, she was effective in the way she described some of the weaknesses of her lab. One major weakness in her lab that she admitted to was the variability of stresses in the subjects. Some subjects may have been stressed due to other reasons that may affect the data. This lab report and experiment was somewhat effective in certain things, but overall the experiment and the conclusions drawn from it are invalid for multiple reasons. One of the largest sources of invalidation comes from the sample size. Thomas’ experiment only included seven test subjects.
Of this seven, five were female and two were male. The gender ratio was not equal and the actual sample size was incredibly small for an actual experiment. Having only seven test subjects limits the accuracy of the data because there would not be enough data to draw conclusions from. Also, the seven subjects did each half of the experiment only twice. Only doing a trial twice can lead to stopping the experiment and collecting of data before the full trend can be seen. The data in possible trials past the second one could have shown trends and relationships that the first two trials did not.
Another reason why the experiment was invalid was because of how many external variables there are in this experiment. Any small jolt, surprise or even thought, can send adrenaline pumping throughout the body and affect both skin temperature and muscle tension. A jolt of adrenaline could alter the data and throw off the entire average of the subject. Also, like Thomas mentioned, external stresses of life can affect the data as well. If a subject is stressed about something that can affect the muscle tension of the frontalis muscle and can also affect the changes in skin temperature.
The experiment also doesn’t account for the effect of room temperature on changes in skin temperature. If the room is cold the skin temperature will decrease slightly due to the external environment. Changes of that sort would completely alter the data in the experiment. The first half of the experiment can also be invalidated by how easily the data recorded can vary. The frontalis muscle is used in moving parts of the eyelids and the eyebrows. Even a slight movement in either the eyelids or eyebrows requires the frontalis muscle to be used and it may skew the data as well.
For the second part of the experiment, the place where skin temperature was measured was not indicative of how skin temperature changes in different areas of the body. Thomas used the index finger of the non-dominant hand to measure the changes in skin temperature and the data found there was used to apply to all skin temperature changes across the body. The reality is that different areas of the body are closer or farther away from the veins and arteries due to the structure underneath.
These differences cause certain areas of the body to heat up quicker or slower than other parts. Also, certain parts of the body have more hair on the skin that others do which can also alter the rate of skin temperature change (Bierman, 1936). Measuring the changes in skin temperature of the index finger is data that cannot be extrapolated completely to the rest of the skin on the body. The implications of this experiment could be great. The conclusions drawn from this experiment have implications in the medical world, the psychology world and even everyday life.
The ability to teach someone to release muscle tension in certain parts of the body through operant conditioning could be incredibly useful for people who have chronic migraines. Sometimes migraines are caused by tension in the muscles surrounding the head. If this is the case and operant conditioning can help assuage that high muscle tension, then it could act as an alternative to traditional Western medicine and pills. Biofeedback mechanisms could be used in controlling other aspects of the body as well such as, heart rate, pain perception, brainwaves… etc.
Even though Thomas’ experiment had many flaws that made the results invalid, the conclusions drawn from the experiment could be crucial and applicable. If operant conditioning could be used to teach humans how to control their bodies in ways that seemed difficult or implausible before, it can have great implications in medicine and other aspects of daily life. It could be used to assuage the side effects of medication and control different aspects of body mechanics. The effects of biofeedback mechanics could be used to revolutionize the way medicine is approached.
