Psych Reaction TIME - Grade: A+ PDF

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Report on Lab Experiment A-Reaction time...

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Introduction The famous experiment the ‘Subtractive Method’ designed by Franciscus Donders in 1869 demonstrated how the speed of thought could be statistically measured through calculating the reaction times of individuals that participated in select tasks (Donders, 1869). The three most commonly used reaction time tasks of the ones that have been used over the years are ‘Simple’, ‘Go/No-go’ and the ‘Choice’. These were also the three reaction time tasks that we used in our experiment that we carried out. The point of the Subtractive Method was to measure how long the reaction process takes, without measuring the direct reaction because this is not directly observable. The ‘Simple’ task was the most simplistic task of them all hence the name, this required us to respond to one stimulus which was the change in light/sound in response we would need to press a button. The ‘Go/No-go’ task was more complex than the ‘Simple’ as it required us to respond to a target stimulus, and not to respond if there was not a stimulus present. Lastly, the ‘Choice’ task required us to respond to multiple stimuli, this was therefore the most complex of them all.

Prior to the ‘Subtractive Method’ there was research carried out by Donders regarding reaction timing in various contexts, one of which was shocks and how they affect human feet. The task was to respond to the shock by pressing a telegraph key with either a right or left arm to indicate whether or not the right or left foot had received the shock. And in the other subject the individual was aware of which foot was going to be affected by the shock. Through this Donders came to the conclusion that there was a 1/15 second difference between these two different subject tasks (Montclair State University, n.d., para 5).This showed that there is a difference in the reaction timing when certain things are made simpler, as these things require less thought processing thus less time to react. This further backs up my hypothesis. This previous research was significant as it showed that Donder’s elaborated on reaction timing when he came up with the Subtractive Method in 1869. Furthermore, this previous research was said to be “the first determination of the duration of a well-defined mental process”.

The Independent variable was the different experiments we carried out (Simple, Gon/No-go, and Choice) experiments. And the Dependent Variable was the mean reaction time(how long it took each individual to respond to the tasks) for each of these experiments. The psychological questions that were to be answered, was that as you add another variable into the experiment (an extra step), the reaction time would get slower and slower. As there is more thought processing needed which requires a greater amount of time, thus the reaction time increases in time (measured in ms). My experimental hypothesis made prior to carrying out the three selected experiments, was that the mean reaction time for the ‘Simple’ experiment would be the fastest reaction, a slower mean reaction time for the ‘Go/no-go’ and again even slower for the ‘Choice’ experiment. This hypothesis was supported by the recent study conducted by (Danek and Mordkoff, 2011), where the three experiments were carried out by nine people, and the reaction times were recorded. The results showing that the mean reaction time for the ‘Simple’ experiment was the fastest at 330.0ms, the ‘Go/No-go’ slower at 369.0ms, and the slowest being the ‘Choice’ at 417.7ms. So based on this and my previous knowledge from previous research, my hypothesis was made accordingly. Method The three tasks in the experiment were performed individually by each person in our tutorial. There were 10 trials for each of the three tasks and they were all in partial report condition. But because the tasks were all completed simultaneously there was potential for distraction. For the ‘Simple’ experiment we were required to react when a stimulus was present on the computer screen, the stimulus was a light (colour) and whenever the light was presented on the screen we needed to press the space button on the computer as quickly as possible. The ‘Go/No-go’ experiment was also under partial report conditions, and had 10 trials. This experiment was more complex than the ‘Simple’ as there was an extra variable added in which was that there was more than response option and we needed to respond to more than one stimulus. We were told by the computer screen to only respond by pressing a button if one colour was presented and if this same colour was not presented then we were not required to press a button. The ‘Choice’

experiment was by far the most complex of them all, as another two variables were added. This experiment required us to press the key “Z” if the colour red appeared on the screen, and to press the key “M” if the colour blue appeared on the screen. This experiment required us to respond to two stimulus, making this the most complex of them all. Results The results from the three tasks for reaction time revealed that the ‘Choice’ task had the lowest mean (fastest reaction time) at 379.5ms. Followed by the next fastest reaction time coming from the ‘Simple’ task at 384.5ms, this was a marginal difference between the results from these two tasks. And finally the slowest reaction time was 435.9ms which came from the ‘Go/No-go’ task. The results did not support my hypothesis made, which was that the mean reaction time would be the quickest for the ‘Simple’ task and the slowest for the ‘Choice’ task, but this was not the case for my experiment.

Descriptive Statistics

N

Minimum

Maximum

Mean

Std. Deviation

simple

10

.21

.84

.3845

.20150

gonogo

10

.33

.71

.4359

.12552

choice

10

.30

.48

.3795

.05818

Valid N (listwise)

10

Discussion The results of the three experiments I carried out didn’t confirm Donders theory. I hypothesized that my Simple experiment would be the fastest reaction, this was 384.5ms. I hypothesized that the ‘Go/No-go’ experiment would be slower, this was 435.9ms. And finally, the ‘Choice’ experiment I hypothesized would be the slowest reaction time of them all and this turned out to be the quickest reaction of all at 379.5ms. However, these results could have been affected by a number of factors such as the environment in which I completed the experiments in, as there was a lot of distractions around me. Also because the ‘Choice’ experiment I carried out was the third and final task, this could have had an effect on the results as I was more familiar with the parameters of the experiment when I got to completing the ‘Choice’ task. This could have led me to react faster than I originally thought. If i was to repeat this experiment I would do it with a different order of each experiment as I believe this affects the reaction times to some extent. Furthermore, isolating students in our tutorial I believe would reduce the potential for distractions and would improve accuracy and validity of the experiment.

The limitations of the experiment was that it was done in a class setting therefore there was a lot of distractions. I felt rushed for time leading up to the experiment therefore this could have had an effect on my reaction timing. While my hypothesis was the same as what Donders found in 1869, there are differences that might exist between the original experiments and current experiments. Another limitation of the experiment, was that we were limited to 10 trials for each task, therefore if we did 20 trials or more, this would give a greater representation and may have further backed up my original hypothesis. Furthermore, when Donders created the ‘Subtractive Method’ it wasn’t done on the computer, as there was no technology like that available at that time. Overall the results I would expect to be the same as back then, but the complexities of the experiment would have changed from then to nowadays.

References

Danek, R. H., & Mordkoff, J. T. (2011). Unequal motor durations under simple-, go/no-go, and choice-RT tasks: Extension of Miller and Low (2001). Journal of Experimental Psychology: Human Perception and Performance, 37(4), 1323–1329.

Donders, F. C. (1869). Over de snelheid van psychische processen [On the speed of mental processes]. (W.G. Koster, Trans, 1969.). In W. G. Koster (Ed.), Attention and Performance II ( pp. 412–431). Amsterdam: North Holland.

Montclair State University. (n.d.). Historical Background and Origins of Reaction Time Research. Retrieved from http://tomperera.com/psychology_museum/mrt.htm...