Integration and summation of both the excitatory and inhibitory neurons have to come together for the end process required for body movement to occur.
The time required for a simple reflex to occur is an example of a reaction time. A simple reflex is monosynaptic; it involves only two neurons and one synapse, this reflex is more commonly observed as the knee-jerk reflex which occurs when the tendon just below the kneecap is tapped. This stimulus in turn causes the muscle to contract, moving the leg. The reflex does not require any brain activity, as the circuitry is contained within the spinal cord itself.
A simple memory task can be done reflexively, but a task that involves a discrimination process, is much slower. Discrimination time will increase with the increased complexity of a task. As the task becomes more complex, more things must be considered and compared, allowing for more options and decisions to be made. In the brain this means more neurons are involved.
There are various factors that influence discrimination time; sleep deprivation is one of them. Welford (1980) found that reaction time gets slower when the subject is fatigued. Singleton (1953) observed that this deterioration due to fatigue is more marked when the reaction time task is complicated than when it is simple, mental fatigue, especially sleepiness, has the greatest effect. Takahashi et al. (2004) studied workers who were allowed to take a short nap on the job, and found that although the workers thought the nap had improved their alertness, there was no effect on reaction time. ( Review on reaction time.htm)
Sleep deprivation is a commonplace occurrence in modern culture. Every day there seems to be twice as much work and half as much time to complete it in. This results in either extended periods of wakefulness or a decrease in sleep over an extended period of time. While some people may like to believe that they can train their bodies to not require as much sleep as they once did this belief is false. Sleep is needed to regenerate certain parts of the body, especially the brain, so that it may continue to function optimally. Certain stages of sleep are needed for the regeneration of neurons within the cerebral cortex while other stages of sleep seem to be used for forming new memories and generating new synaptic connections ()
In the proposed experiment, we wish to replicate a previous experiment done on reaction time; we shall modify the experiment by measuring the reaction time of completing a simple task (2piles) and a complex task (4piles) in relation to hours of sleep. We shall have 20 participants, who will be randomly allocated with numbers. In the experiment the participants would have 2 tasks to complete; they would be dealing a deck of cards into two piles randomly and also into four piles according to their suites. The first task is the simpler of the two. The second task is more complex, it adds more decision point, as choices are increased.
Our hypothesis is that there would be a significant difference in performance of both task, the complex task (4 piles) and the simple task (2 piles) in relation to the number of hours of sleep. This study is an original study as there have been no previous studies done to date to test the difference the effect of sleep on reaction time of a simple task (2piles) and a complex task (4piles).
A second hypothesis will be running in the experiment to support previous experiments, the second hypothesis is that the participants will be significantly quicker in the simple task (2 piles) than in the complex task (4 piles). This study is not an original study as it has been done in the past.
METHODS
Design
The design used was a repeated measure, as each of the participants repeated both conditions. The first part of the experiment involved participants completing a simple task (2piles) and the second part involved participants completing a complex task (4 piles). The dependent variable is the reaction time of the participants and the independent variable is the simple vs. complex task. Another variable used in the experiment is the number of hours of sleep. The mode of the allocation was random
Participants
This experiment was carried out with 21 third year psychology students in Dublin Business school of Arts. It is a convenient sample. The participation of these students was voluntary. The 21 students participated in both sections of the experiment.
Materials
In this experiment numbers were randomly written on 21 pieces of paper and put into a bag which participants had to choose from, to determine their positions in the experiment. A desk and chair was used by the participant while they performed the experiment. The participants had to deal a deck of cards in the experiment, 4 decks of cards was used. The experiment was conducted in a bio-feed back lab. The time it took for the participants to complete the experiment’s conditions was timed using a stopwatch. There was an experimenter as well as a timer present. Instruction sheets were used to give the participants instructions A pen and recording sheet was used to record the time participants completed the task in.
Procedure
The 20 participants randomly chose their order numbers by picking out numbers in a bag. The participants had to wait in the waiting rooms and were later brought into the bio-feed back room, in the order of their chosen numbers. The deck of cards was already on the desk as soon as they walked into the room, instructions were read out to them as they sat down. The participants were observed by the experimenter while carrying out the tasks, so that they put the cards in the right other. Another instruction was read out to them as the next condition of the experiment began. Participants only went into the bio-feed back room once, so they completed both conditions of the experiment at the same time. The timer noted the length of time it took each participant to complete the task and also shuffled the deck of cards between each participant, while the experimenter recorded the time in both conditions. The simple condition was done first and then the complex condition done next. At the end of the experiment, participants were asked approximately how many hours of sleep they thought they had the night before, they were thanked for participating in the experiment and they were told to sign the attendance sheet before they left the room and asked to call the next participant. Participants 1 to 20 went into the experiment room in turns.
Below are the two sets of instructions given out to the participants in the two conditions:
Condition 1: Please place these playing cards randomly into 2 piles as quickly as possible. The timer would tell you when to start, start after he gives you the go ahead.
Conditions 2: Please place these playing cards into 4 piles, according to their individual suits (spades, clubs, diamonds and hearts), as quickly as possible. The timer would tell you when to start, start after he gives you the go ahead.
RESULTS
The following are the results from the tests carried out in the experiment:
Table 1: Correlation table showing the relationship between hours of sleep and the time it took participants to complete both task
There is a weak negative non-significant relationship between hours of sleep and the time it took to complete the simple task (2 piles). The longer the hours of sleep a participant had the shorter the time it should take them to complete the simple task, although this is not significant from the results. There is an even weaker non-significant relationship between hours of sleep and time it took to complete the complex task. The shorter the hours of sleep a participant had the longer the time it should take them to complete the complex task, although this is also not significant form the results. From the results gotten, it can be seen that hours of sleep has no influence on the time it takes to complete both tasks.
Table 2: Results from the paired sample t-test showing the time it took to complete a simple task (2 piles) and the time it took to complete a complex task (4 piles)
The mean of the time to complete the simple task is 24.1043 and the time to complete the second task is 42.3548. From the results, a difference can be seen between the mean of both tasks, as the simple task is lower than the complex task. The standard deviation for the simple task is 2.75423 and the complex task is 6.54041. There is more variation in the S.D of the complex task than in the simple task, as it has taken a shorter time to complete the simple task and a longer time to complete the complex task.
Table 3: Descriptive Statistics results of the number of hours of sleep, time it took to complete the simple task and time it took to complete the complex task.
A second descriptive statistics was collected for the hours of sleep and the relationship between the time it took to complete both the simple and the complex task. The mean of the hours of sleep can be seen to be lower than the mean of both the times for the simple task and the complex task. The standard deviation can also be seen to be lower. This shows that it has no influence on the time it took to perform both the simple and the complex task.
From the data gathered in this experiment we carried out a correlation test, which showed that there is a weak non significant relationship between hours of sleep and the time took to complete both the simple and complex task; r = -.236, p=.303, 2-tailed and r = -.073, p= .753, 2 tailed. This test showed that there is no significance between hours of sleep and performance time of both a simple and complex task.
A paired samples t-test was also performed from the data gathered, this paired samples t-test showed that there is a significant difference between the time it took to complete the simple task(2 piles) and the time it took to complete the complex task(4 piles); t (20) = -14.150, p<.001, 1 tailed. The result showed than participants performed better in the simple task, than in the complex task. See appendix for SPSS output.
DISCUSSION
The main hypothesis of the experiment is that there would be a significant difference in performance of both task, the complex task (4 piles) and the simple task (2 piles) in relation to the number of hours of sleep. In other words our hypothesis was that a difference would be seen in the performance time of the both tasks between those who had longer hours of sleep and those who had lesser hours of sleep. From the analysis we performed on our data we can conclude that our hypothesis was not supported. Therefore we failed to reject the null hypothesis For example if we take our correlation results, we can noted that there was a weak negative correlation between hours of sleep and time it took to complete the simple and complex task.
A second hypothesis running in the experiment to support previous experiments was that the participants will be significantly quicker in the simple task (2 piles) than in the complex task (4 piles). To support this analysis we performed a paired samples t-test, which confirmed that there is a significant difference between both conditions. Therefore we reject the null hypothesis.
Our main hypothesis although it was not supported can be applied to the research done by Welford (1980), the research showed that reaction time gets slower when the individual is tired. Research also supports our result, Takahashi et al. (2004), studied workers who were allowed to take a short nap on the job, and found that although the workers thought the nap had improved their alertness, there was no effect on reaction time. This goes to prove that hours of sleep have no effect on an individual’s performance in completing a task.
Singleton (1953) observed that this deterioration due to fatigue is more marked when the reaction time task is complicated than when it is simple; this research supports our second hypothesis. The simple task was much faster because it did not involve a discrimination time, unlike the complex task. In the simple task less neurons are used and not much variations in movement as cards were randomly distributed into two piles In the complex experiments more neurons and synapses are involved, therefore movement was more haphazard. Some of the participants would have found the complex task much harder than others, as movement depended on how participants arranged the cards.
Various criticisms can be noted from the experiment conducted; the sample size in the experiment was only 21 students, this sample size is small and cannot give us an accurate result for the population. People with practice in sorting out cards would do better regardless of the hours of sleep they had and the nature of the task. Participants estimated verbally how many hours of sleep they had, so we had to rely on individuals self report. Participants were being observed this could have had a negative effect on them, as participants would have made lots of mistakes while trying to ensure they performed well in the tasks. The participants were psychology students who knew what was expected of them, they could have performed as the experiment required them to. The experiment was performed within a laboratory setting where all inferring factors can be controlled, there it may not hold validity outside the laboratory. Hours of sleep were asked after the tasks, which made it easier for participants to carry out the task. Participants were not told exactly what method to complete the complex task in; some arranged the four piles in a square shape, while some arranged it in a straight line.
This experiment can be modified for future experiments, reaction time could be measured in relation to gender, as males are known to have faster reaction times than females. Left hand vs. right hand could be another direction the experiment could go in as it is noted that left handed people perform well with both hands while right handed people performed well with only their right hands. Participants could be monitored so that they each have the same exact number of hours of sleep, and then reaction time can be tested. Instead of having one simple and complex condition, participants could each be tested on 2 simple and complex tasks. After the experiments participants were asked the estimated number of hours of sleep they had the previous night, this made it easier for them, a future direction to go would be ask participants before the experiments so that it can have an influence on the way they performed in the task. If the experiment is to be performed again, hours of sleep of the participants could be divided into two; those with the lower hours and those with the higher hours of sleep, reaction time of both groups can be compared against each other.
A lack of insight into the influencing factors can leave us with inaccurate results, one must take all the above criticisms and future direction into consideration when conducting future research in this area.
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