So, how about when something touches us and we move? What sorts of smaller things are going on? That's what we want to look into today.
A touch starts signals moving in sensory neurons which eventually cause signals to move in motor neurons which eventually cause muscle contractions and movement. How long does it take to move when one is touched? And how much of that time is the time it takes for signals to move from the endings of sensory neurons to the endings of motor neurons? How much of that time is the time it takes muscles to contract and cause movement? That's what we'll be looking at in the first part of the lab.
In the second part of the lab, you and your team should develop your own questions and observation protocols to explore some interesting aspect of what is going on in reacting. For example, would you expect the time taken to be different if the stimulus occurred at a more distant location on the body? On the same side as the response as opposed to the opposite side? If the response was with your dominant or your non-dominant hand? Would you expect the time to change if you were tired? preoccupied? had recently had coffee? Is it the time that signals take within the nervous system that changes or the time for muscles to contract and cause movement? Or both?
Don't try and answer ALL the questions. Pick one (or think up one) that you're interested in and have a guess about. And collect enough data so you have some confidence in your conclusions about that situation. And write up your question/hypothesis, observations, conclusions in the lab forum.
HYPOTHESIS: The dominant hand will have a faster reaction time than the subordinate hand.
Note: we are both right handed.
Nancy Right Hand:
- TTL latency-- .22
- Latency one-- .11
- Latency two-- .11
- TTL-- .14
- one-- .08
- two-- .06
Talia right hand:
- TTL-- .20
- one-- .04
- two-- .16
- TTL-- .35
- one-- .31
- two-- .04
Nancy Left hand
- two-- .10
- two-- .05
Talia Left hand
- two-- .04
OBSERVATIONS: We observed that there seemed to be faster respnse times in the dominant hand. This was the case in three out of four trials. The fourth trial could have been influenced by a numer of factors, including outside noise, thought patterns, etc.
Hypothesis: With the assumption that the dominant hand is more used than the non-dominant hand, the time of reaction for the dominant hand would occur in less time than it would for the non-dominant hand.
Observations in the thumb of the dominant hand:
1. muscle activity 5.93
total time of reaction 5.97
initial time of stimulus 5.56
Latency 1 = 0.37
Latency 2 = 0.04
2. muscle activity 4.2
total time of reaction 4.29
initial time of stimulus 3.98
Latency 1 = 0.22
Latency 2 = 0.09
3. Muscle activity 4.5
total time of reaction 4.61
initial time of stimulus 4.35
Observations in the thumb of the non-dominant hand:
1. muscle activity 4.62
total time of reaction 4.69
initial time of stimulus 4.48
Latency 1= 0.14
2. muscle activity 4.23
total time of reaction 4.27
initial time of stimulus 4.01
Latency 1 = 0.26
Latency 2 = 0.04
3. muscle activity 4.84
total time of reaction 4.86
initial time of stimulus 4.67
Our initial assumption that the dominant hand would react faster to the stimulus was proved wrong: the time between the stimulus and the movement of the muscle is approximately the same and sometimes faster in the non-dominant hand and the time of the muscle contraction shows a faster movement in the non-dominant hand. Therefore, there is no correlation between a dominant side of the body and its time of reaction and movement.
Katie: Latency 1 (average) 0.2 Latency 2 (average) 0.05
Manuela: Latency 1 (average) 0.075 Latency 2 (average) 0.041
Bessy: Latency 1 (average) 0.2 Latency 2 (average) 0.05
La Toiya: Latency 1 (average) 0.22 Latency 2 (average) 0.06
Our hypothesis states that when a person can see the stimulus coming, both latency periods will be shorter.
Eyes open, watching stimulus:
Katie: Latency 1 (average) 0.07 Latency 2 (average) 0.03
Manuela: Latency 1 (average) 0.02 Latency 2 (average) 0.062
Bessy: Latency 1 (average) 0.03 Latency 2 (average) 0.06
La Toiya: Latency 1 (average) 0.04 Latency 2 (average) 0.07
Our hypothesis was only partially correct. The response time (Latency 1) is shorter, but muscle movement (Latency 2) still takes about the same amount of time.
Melissa: TL - .383, L1 - .370, L2 - .330
Abby: TL - .177, L1 - .148, L2 - .136
Melissa: TL - .266, L1 - .246, L2 - .041
Abby: TL - .291, L1 - .246, L2 - .047
Summary: After performing three trials on each variable (dominant/non-dominant), we averaged the times and came up with the data presented. Abby's data was consistent with the hypothesis, but Melissa's was not. The data therefore was could not support this hypothesis or the opposite of this hypothesis, because of the inconsistency of our data.
We found that L1 was consistently slower than L2, but the lag time varied significantly. Why?
These discrepancies may have been due to the fact that stimulus was applied to the same arm in both experiments.
Test Subject 1 (Natalya):
Latency 1(between stimulus and muscle contraction): .18, .24, .12
Latency 2 (between muscle contraction and response): .07, .07, .07
Test Subject 2 (Sarah):
Latency 1: .28, .18, .16
Latency 2: .12, .07, .09
Test Subject 3 (Brittany):
Latency 1: .04, .21, .29
Latency 2: .06, .07, .06
For the second part of the lab, we attempted to determine whether or not the location of the stimulus on the test subject's body affected their reaction time. We tested 3 stimulus locations: the original data from tapping on the leg, and then 2 new locations (3 trials each) on the head and the foot. Our hypothesis was the the closer the stimulus is to the brain, the faster the reaction time. Therefore, we hypothesized that the head tap would produce the fastest reaction time and the foot tap would produce the slowest. Here is our data in seconds:
Test Subject 1:
(Natalya - Head):
Latency 1: .27, .16, .11 Average: .18
Latency 2: .05, .51, .06 Average: .20
(Natalya - Ankle):
Latency 1: .24, .28, .15 Average: .22
Latency 2: .05, .05, .12 Average: .07
Test Subject 2:
(Sarah - Head):
Latency 1: .17, .19, .13 Average: .16
Latency 2: .05, .10, .09 Average: .08
(Sarah - Ankle):
Latency 1: .25, .14, .20 Average: .19
Latency 2: .07, .15, .07 Average: .09
Test Subject 3:
(Brittany - Head):
Latency 1: .22, .22, .19 Average: .21
Latency 2: .07, .05, .08 Average: .06
(Brittany - Ankle):
Latency 1: .26, .36, .27 Average: .29
Latency 2: .06, .03, .04 Average: .04
Overall, our results for the latency 1 period (from the stimulus to the muscle action) is faster when the stimulus location was closer to the head. But the latency 2 period (from the muscle action to the response) varied by test subject. So though our results appear to corroborate our hypothesis, the results are not conclusive. Our hypothesis for further research is that the latency 2 period is independent of stimulus location in relation to the head. We do believe that our data supports our claim for at least the latency 1 period.
Hypothesis: Our hypothesis for this experiment was to test the difference in reaction between the dominant hand and the other. Both subjects were hit on their knee in the area above the patella.
- standing up during both trails
Right Hand: (dominant)
Latency Total: -.240 (Trial 1)
Latency Total: -1.05 (Trial 2)
Latency Total: -1.186 (Trial 3)
Latency Total: -.081 (Trial 1)
Latency Total: -.107 (Trial 2)
Latency Total: -.167 (Trial 3)
- sitting down in the chair
Right Hand: (dominant)
Latency Total:-.187 (Trial 1)
Latency Total:-.198 (Trial 2)
Latency Total: -.184 (Trial 3)
Latency Total:-. 194 (Trial 1)
Latency Total: -.136 (Trial 2)
Latency Total: -.152 (Trial 3)
See first conclusion (ie experiment done by the first group)
We tested the muscle reaction times on both our left and right hands. All of us are right-handed. We hypothesized that the muscle contraction times would be faster on our right hands.
Data (Average of 3 tests):
Right Hand: 0.05 milliseconds
Left Hand: 0.06 milliseconds
Right Hand: 0.03 milliseconds
Left Hand: 0.06 milliseconds
Right Hand: 0.03 milliseconds
Left Hand: 0.03 milliseconds
The data seems to have supported our hypothesis. Lindsay's reactions could be explained by the fact that she was ambidextrous as a child but got used to using her right hand to write. The muscles in the right hand are more trained to reacting to stimuli. This is why it takes them less time to shorten and press the button. It was interesting that the times between the initial stimulus and beginning of muscle reaction did not vary significantly between hands. This could lead to a further hypothesis that since the arms are equidistant from the central nervous system, it takes the left and right equal amounts of time to process the reaction signal.
Hypothesis: We observed the reaction times of the dominant vs. the non-dominant hands. We hypothesized that the dominant hand would have a faster reaction time than the non-dominant hand.
Note: Each of the women observed was dominant in her right hand.
first figure = time from stimulus to muscle activity
second figure = time from muscle activity to response
1.) 90 ms
2.) 4 ms
3.) 78 ms
1.) 140 ms
2.) 126 ms
3.) 120 ms
1.) 185 ms
2.) 252 ms
3.) 214 ms
1.) 153 ms
2.) 143 ms
3.) 141 ms
1.) 77 ms
2.) 154 ms
3.) 121 ms
1.) 97 ms
2.) 150 ms
3.) 236 ms
Anna's data was consistent with our hypothesis in regards to the time from the stimulus to muscle activity; however, J'London's and Enor's data was inconsistent. In regards to the time from muscle activity to response, we did not see enough of a change in time from dominant to non-dominant hand for it to be significant.
We cannot say for sure if our hypothesis was correct or not based on our data. Perhaps there is no difference from dominant to non-dominant hand. We attribute our inconsistencies in observations to expectancy, which hand was tested first, desensitization of reactions, etc.
We studied the effect of distance of stimulus from the brain on reaction time. The body parts we tested were upper arm, ankle, and head, and we tested each body part of each person three times. We hypothesized that the further from the brain the stimulus, the longer the response time would be.
Arm: 0.17 sec
Head: 0.21 sec
Ankle: 0.38 sec
Arm: 0.51 sec
Head: 0.23 sec
Ankle: 0.35 sec
Arm: 0.40 sec
Head: 0.37 sec
Ankle: 0.41 sec
These results do not support our hypothesis. There are other factors that influence reaction time but distance does not appear to be significant.
Hypothesis: Poking people in places farther away from the brain will take them longer to react to the stimulus.
b. knee: -0.54-0.03
b of shoulder: 0.22-0.01
l. hand: 0.26-0.03
Conclusion: We decided that there is no correlation between the poking and the distance from the brain because in some cases, the reaction time was greater when stimulated farther away from the brain. Our data was inconsistent, which leads us to conclude that there are other factors that influence the reaction time.
We tested the effect of using the right vs. left hand to push a button on total response time. Does the hand used make a difference in total reaction time?
Hypothesis: Total reaction time will be higher for the left hand in right-handed people than for the right hand. This will occur because right-handed people have better developed nerve pathways and muscles on the right side of the body than the left.
We took 5 measurements for each the right and the left hand in three subjects (a total of 30 pieces of data collected). We then averaged the 5 left- and right-hand data points for each person, resulting in one figure for each hand of each person. To keep variables other than the experimental (which hand) constant, subjects positioned their arm on the table and held the button in the same way each time. The administrator-of-touch hit the subject in the same place each trial with as constant a force as possible. The subjects closed their eyes so they would not overly anticipate the time of touch administration.
Our averages were as followed:
Total Average Time between stimulus and response
right hand- .18
left hand - .20
right hand- .19
left hand- .18
right hand - .20
left hand - .16
These data do not support our hypothesis. Although the left hand response time was longer for one subject (A), it was actually shorter for the other two cases -- the reverse of our hypothesis. Moreover, the differences among all of the data points -- no more than .04 in total, and no more than .02 in all but one cases -- do not appear significantly / proportionally large enough to suggest any significant trend. Rather, the differences in response time seem attributable to chance / experimental error.
The fact that the left hand response time was slightly longer in one case and slightly shorter in two cases suggests that these differences, rather than representing a trend, are randomly distributed around some average. This means that the response times for right vs. left hands are probably NOT significantly different from each other, as a whole. Nor do they seem to be significantly different for any one subject we tested.
Our results also indicate, by induction, that the neural pathways and muscles involved with the left vs. right hands -- and perhaps the left and right sides of the body? -- do not significantly differ.
We hypothesized that the closer the probe was located to the brain on the body, the shorter the distance would be for the message to travel from the probed area of the body-to the brain-and back to the subjects hand for a response.
We took 3 samples of responses from being probed in 4 diffrent parts of the body: 1) The thigh, 2) the toe, 3) the shoulder, and 4) the forehead. We wanted to use body parts that we 1) a moderately far place on the body as a type of control, 2) the farthest place on the body from the brain, 3) a place that is between the brain and the hand that will be responding, and 4) the place closest to the brain. We wanted to observe which place would elicit the quickest response.
L1 Neural Processing
L2 Motor Response
TL L1+ L2
Trial 1 L1= .3147
Trial 1 L1= .1275
We determined that the shortest time between L1 and L2 on average would indicate that the travel time of the neural message to response was fastest. .246 was the average TL for our control (the thigh.) .278 was the average TL for the toe test, which supported our hypothesis. .3337 was the average TL for the shoulder test, which was extremely suprizing to us, as it would have little space between the hand and the brain and this response time took longer than the toe. (we poked on the arm that we were responding with.) And finally, the average TL on the forehead test was .607 which was far greater than we had expected.
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