Somatosensation: Two-Point Threshold Lab Report 2 Alexis Ziemba Florida State University Introduction Somatosensation was defined in the lab manual as the sense of touch. The four types of mechanoreceptors that were discussed in class were the Merkel complexes, Ruffini endings, Meissner’s corpuscle, and the Pacinian corpuscle (Lab Manual). The Merkel complexes were slow adapting mechanoreceptors whose primary function was to discriminate the texture, or pattern of an object (Lab Manual). The Ruffini endings were also slow adapting mechanoreceptors, but their primary function was to differentiate finger position and stable grasps (Lab Manual). The Meissner’s corpuscle was a fast adapting mechanoreceptor whose primary …show more content…
function was to detect low frequency vibrations on the skin (Lab Manual). The final receptor, the Pacinian corpuscle was a fast adapting mechanoreceptor whose primary function was to detect high frequency vibrations on the skin (Lab Manual). The goal of experiment four was to determine the two-point threshold of the participant through the use of a dial caliper placed on various spots on the participant’s body (Lab Manual). The areas included in the experiment were the palm of the hand, finger, forearm, and back. According to the lab manual, the skin on the human body registers touch, or pain through the use of mechanoreceptors found all over the skin. The receptors could be found on parts of the body with hair, or parts of the body without hair, also known as glaborous areas (Lab Manual). Receptors could also be found in either the dermis or the epidermis (Lab Manual). The mechanoreceptors located all over the body can be activated and are sensitive to cold/heat (thermoreceptors), pain (nociceptors), and pressure (mechanoreceptors) (Lab Manual). Once an area of the body was touched by another object, the mechanoreceptors became activated which sent the message of touch to the brain where then it could be processed (Lab Manual). By definition, the two-point threshold is used to determine how far away two points must have been before a participant noticed that there were two points touching him or herself instead of one (Lab Manual). In regards to the two-point threshold, the smallest threshold could be found on the most sensitive areas. The further away the arms of the dial caliper were, the larger the two-point threshold, and therefore the less sensitive the area. In the experiment, the absolute threshold was measured by 0.001 mm, and was used to determine the difference between the two measurements, which created the sensation of two points (Lab Manual). The reasoning for the two-point threshold differences through the various places on the body were due to the amount of area that was dedicated to that specific part of the body in the somatosensory cortex of the parietal lobe (Lab Manual). The term for the allocation of sensory resources to specific parts of the body was known as the homunculus (Lab Manual). Methods The material list in experiment four was brief and rather simplistic.
The only materials needed in the experiment were a single dial caliper, and the skin of the participant that was measured (Lab Manual). A dial caliper was available for purchase online through the use of a simple Google search. The dial caliper was a long metal object with one dial, that was adjustable and that moved the two sharp points at the end of the caliper further away from each other. The purpose of the dial caliper was to measure the length of space between the two sharper points of the dial caliper. In the experiment, the experimenter was a 20 year old, female, psychology student at Florida State University. The role of the experimenter was to place the dial caliper on the skin of the participant in various places on the palm, finger, forearm, and back in order to record the amount of area needed between the points of the dial caliper before the participant was able to realize that two points were touching the skin rather than one (Lab Manual). The experimenter also used the method of limits through the use of ascending trials in order to record the participant’s ability to discriminate between the two points on the dial caliper (Lab Manual). Three trails were to be conducted by the experimenter before the experiment was to be considered completed. It was essential to ensure that the two points of the dial caliper were touching the participant at the same time and with the same amount …show more content…
of pressure in order to stay consistent throughout the three trials on each body part (Lab Manual). The participant in the experiment was a 20 year old, female, psychology student at Florida State University. The role of the participant was to sit quietly with their eyes closed, or facing away from the experimenter, and wait patiently for the dial caliper to touch their skin (Lab Manual). The participant was then to report whether they felt one, or two distinct points touching their skin. The participant was also expected to sit through three ascending trials for each body part that was to be tested. Results According to information presented in the lab manual, which stated that the participant’s finger would have the smallest two-point threshold, the data collected confirmed that finding. The data collected did not support the idea that the palm was the second most sensitive body part in regards to the two-point threshold. The data also did not confirm the idea that the back was the least sensitive body part in the experiment. According to the calculations acquired in experiment 4, the finger was the most sensitive part of the body in regards to the two-point threshold, and the palm of the hand was the least sensitive part of the body in regards to the two-point threshold, as seen in figure 1.
In regards to figure 1, the means were calculated using a simple formula which consisted of finding (x1+x2+x3)/3 (Lab Manual). In the formula, x1 was the recorded threshold from trial 1, x2 was the recorded threshold for trial 2, and x3 was the recorded threshold from trial 3. The formula was repeated and calculated for each body part. Once the means were calculated, they were placed into a graph and displayed in figure 1. The thresholds used to calculate each mean were not highly variable between trials. The data recorded over each trial were highly consistent between one another, except for a slight deviation in the measurements recorded on the palm of the hand. During ascending trial three on the palm, the results deviated from the norm in reference two the two prior trails. On trial one and two, 0.05 was the only measurement that was not felt. On trial three, not only was 0.05 not felt, but 0.10 was also not felt, which deviated from the norm set forth in the two prior
trials. Discussion The findings of the experiment confirmed the findings that the finger is the most sensitive part of the body in regards to the two-point threshold, but could not confirm the rest of the pattern, which states that, the palm, forearm, and back follow sequentially. The results of the study could have explained that the differences in two-point thresholds could be due to the representation presented in the homunculus. If an area had more representation on the homunculus, there should have been more mechanoreceptors, and it would have been safe to say that should have been shown in the data. Also, it makes sense to say that the finger would have had more mechanoreceptors than the back because we felt our world with our hands, not with our backs. It is also safe to say that the finger would have had more mechanoreceptors than the palm because our fingers were used more to determine objects more than our palms. Although the data collected in experiment four did not match the anticipated results presented in the prior lab period, many extraneous variables could have altered the data. The results acquired by the experimenter demonstrated that the participant did not struggle at all with differentiating the fact that there were two points touching her skin. The results could have been inaccurate due to the fact that the participant had a migraine the day of lab, which may have increased her sensitivity and ability to recognize the two points easier than an individual that did not have a migraine. The experimenter might have also touched the participants skin at an angle that could have exposed the two points easily to the participant. The participant also could have had a bias, because she knew all along that there was going to be two points touching the skin at all times rather than one. In order to cut down the amount of variables that could have influenced the study, some new tactics could be implemented in order to reduce the issues of bias and incorrect administration. To rule out bias implemented by the participant, only the experimenter prior to the experiment can read the lab manual, therefore the participant is unaware of the difference that there will always be two points touching the skin at any given time. It might also be helpful to ensure that the participant is in good health, free from any illness that could increase skin sensitivity, to alleviate anymore bias. After the completion of the experiment, more questions arose for the participant and the experimenter alike. Since the face was represented more in the image of the homunculus, how much more sensitive would the face be than the finger in regards to the two-point threshold? The question could be answered by a simple change in the experimental design. If the finger, face, forearm, and back are tested, there would be more of a difference in two-point thresholds throughout the experiment possibly leading to more interesting results. References Sensation and Perception Student Lab Manual. (n.d.). EXP3202C.
Another weakness in the experimental design was that the reliability of the experiment was very low. As each test subject was only tested against each amount of prior exercise once, the impact of random errors is likely very large, which can be seen by the spread of the data on the graph. Although, this was attempted to be rectified by averaging the results of all four test subjects, it does not improve reliability too
The study was set up as a "blind experiment" to capture if and when a person will stop inflicting pain on another as they are explicitly commanded to continue. The participants of this experiment included two willing individuals: a teacher and a learner. The teacher being the real subject and the learner is merely an actor. Both were told that they would be involved in a study that tests the effects of punishment on learning. The learner was strapped into a chair that resembles a miniature electric chair, and was told he would have to learn a small list of word pairs. For each incorrect answer he would be given electric shocks of increasing intensity ranging from 15 to 450 volts. The experimenter informed the teacher's job was to administer the shocks. The...
Cizek, G. J. (2003). [Review of the Woodcock-Johnson III.] In B. S. Plake, J. C. Impara, & R. A. Spies (Eds.), The fifteenth mental measurements yearbook (pp. 1020-1024). Lincoln, NE: Buros Institute of Mental Measurements.
...e been beneficial to the experiment. An error may have occurred due to the fact that measurements were taken by different individuals, so the calculations could have been inconsistent.
When comparing quantitative measures such as gravimeter with visual analog scales, the quantitative measures, subjective ratings have a relatively high level of diagnosis sensitivity and specificity (48,49B). This method, however, is preferably used in research field, and is rarely used in clinical practice.
The experiment consists of two people that take part in a study of memory learning, one of them referred to as the "Teacher" and the other as the "Learner." The experimenter explains that the study's main goal is to observe the effect of punishment on learning. The learner will be seated in something similar to the electric chair, his arms will be strapped and an electrode will be attached to his wrist. The learner will be told that he will be tested on his ability to remember the second word of a pair when he hears the first one again. If he makes a mistake, he will then receive electric shocks of increasing intensity.
For this statistical inference, the question was whether the means were truly different or could they have been samples from the same population. To do draw a conclusion, we must first assume normal distribution. We must also set the null hypothesis to m1 - m2 = 0. And per this assignment we must set the a-level at .05 and the hypothesis alternative to m1 - m2 ¹ 0; thus requiring a two-tailed test.
Going into details of the article, I realized that the necessary information needed to evaluate the experimental procedures were not included. However, when conducting an experiment, the independent and dependent variable are to be studied before giving a final conclusion.
The independent variables in this experiment are the time and the foils presented to the subject. The dependent variable is the discrimination index. The...
The experiments were quite simple, in that there was a seemingly harmless task to be performed, and the participants were instructed to choose the estimation of the lengths of a line when compared to two ...
In this lab we apply the technique known as a two point discrimination test. This test will allow us to determine which regions of the skin are best able to discriminate between two simultaneous sensory impulses. According to (Haggard et al. 2007), tactile discrimination depends on the size of the receptive fields located on the somatosensory neurons. However receptive fields for other types of sensations are located elsewhere. For vision we find that the receptive fields are located inside the visual cortex, and for hearing we find receptive fields in the auditory cortex. The ability for the body to discriminate two points depends on how well that area of the body is innervated with neurons; and thus conferring to the size of the receptive fields (Haggard et al. 2007). It is important to note that the size of the receptive field generally decreases in correlation to higher innervations. As was seen in the retinal receptive fields, the peripheries of tissue had contained larger receptive fields (Hartline, 1940). In our test we hypothesized that the finger region will be able to discriminate better than the forearm. This means that they will be much more innervated with neurons than the forearm, and likewise contain smaller receptive fields. This also means that convergence is closer to a 1:1 ratio, and is less the case the farther from the fingers we go. We also think that the amount of convergence is varied with each individual. We will test to see if two people will have different interpretations of these results.
... affected the data table. Not going in 0.5 intervals for every muscle at every workload would conclude to inaccurate data if not all electrical stimuluses’ were tested.
4) Describe the methods in your words.- Karate athletes that were competing in the same tournament were selected and volunteered to be tested on their auditory and visual reaction times. These included auditory reaction time, simple reaction time, and choice reaction time. There were 227 athletes that participated in the study and ranged from the ages of 10 to over 18. The researchers conducting the study followed the same protocol for each participant, which included the athlete's using their dominant hand during the
Weiner, I. Healy, A. Freedheim, D. Proctor,R.W., Schinka,J.A. (2003) Handbook of Psychology: Experimental psychology,18, pp 500
I have spend frustrating hours trying to find the right solution. I could have looked up the answer but I wanted to figure it out on my own. I wanted the challenge. That is why I want to be a Benjamin Franklin Scholar. The program challenges me to understand the mystery humans are and their place in this world and the BFS seminars require me to emerge deeply into a topic. “Introduction to Experimental Psychology”, for inst...