Within the accuracy of the manufacturing process all volumes of ‘ DR Pepper’ could be taken as the same. After an interval of half an hour the same sequence of experiments was repeated.
Results: These are presented in the data sheet, a summary is highlighted below.
Table 1 showing times before alkaloid consumption
Table 2 Showing times after consumption of alkaloid.
Treatment of Results:
The original data is shown in the spreadsheet. Bar charts were constructed showing times for three bells for each student both before and after caffeine intake. A similar set of bar graphs was constructed for the mean times between bells both before and after.
Discussion.
In looking at the graph of reactions times up to three bells A clear trend is seen. All observations of pupils after the drink have recorded lower times except 1 (Sheha). Rital and Jita appear to have improved their respective performances quite considerably. The pupil (Rajan) who inhaled the nicotine later on in the experiment appears to have improved on his time considerably.
However this same pupil after some half an hour after consuming the ‘Dr Pepper’ recorded very similar times both before and after. With perhaps a two second improvement on his performance. It is of interest to note that his performance under caffeine was better than under nicotine.
A ‘t’ test’ shown on a data sheet indeed confirms the suspicion, that at the 5% level of significance there was no difference in the means of Rajan’s times before his smoking a cigarette compared to after. However at the 1% level there was found to be a difference. Unfortunately this is such a low level of significance that one should put too much weight on these findings. From this one result we could hardly suggest that nicotine is a far less effective chemical in causing improved performance than caffeine. However caffeine has certainly shown the capacity for performance enhancement based on this data.
In looking at the table of results for the mean time between bells both before and after nicotine a mixed set of results appears. Jita certainly seems to have improved her performance greatly; Lina also improved markedly, with Rital less so. All of the other pupils seem to have fared worse on this experiment.
It was decided to undertake a Wilcoxon test applied to these data, with the hypothesis Ho that the median times before taking caffeine were the same as those after consumption. Wilcoxon is a non-parametric test and does not assume a normal distribution of data. It is also suitable for paired comparisons. The Mann- Whitney test is more useful for unpaired results. The data in each experiment was expressed as mean time between bell. The evidence suggests that no difference in these median times has occurred
For the results of time taken to achieve three bells, in view of the fact that each student performed six replicates and there were seven students in two classes, males and females it was thought worthwhile to carry out an analysis of variance test or anova. The details of the calculation are presented in the spreadsheet. In the notation of Rolfe and Sokal, the two groups of students males and females represent the blocks. Their experimental performances represent the treatments.
The calculation steps are set out in the spreadsheet data. Fundamentally although a difficult exercise the analysis revolves around computing the squares of total data, and the square of the blocks and treatments. Looking at the table of values, the mean square error is the largest item and according to Rolfe and Sokal this would infer that there is no significant difference between treatments or groups.
Given further the calculations of the ‘t ‘ test giving a value of t less than the critical value supplied from tables at the 5% level of significance for the nicotine experiment and the finding that median time intervals were not significantly different from the Wilcoxon test, Although the data has indicated improved results, the statistical calculations show that these are not significantly different, and one could now put forward a hypothesis that these chemicals do not affect reaction time. given this ‘ t’ test and the anova data. The statistical tests tend to confer doubt on the experiment, but two rays of hope were seen. At the 1% level of significance a difference in mean reaction times after consumption of nicotine compared to before is seen, plus the fact that measurable differences in performance times were obtained.
There is a great deal of biological significance in the chemicals caffeine and nicotine. Interestingly although nicotine is found in the tobacco plant there are receptors on the surfaces of cells in the human body that recognise this group of chemicals. An important neurotransmitter Acetylcholine (Ach) plays a role as a primary chemical messenger. By having a similar structure to Ach, both Nicotine and Caffeine can mimic the role of Ach. In essence such cholinergic chemicals i.e. those that mimic ACh excite the autonomic and central nervous systems. These chemicals can release in the adrenal glands for example other primary messengers (hormones) that can alter the temporary biochemical balance in the cells and tissues. For example in this case stimulating the heart rate, increasing blood sugar, releasing glycogen from the liver, and so on.
Caffeine has been further shown to play a role in the release of some calcium ion stores in the endoplasmic reticulum. Calcium plays a vital role in the physiology of muscles. In summary caffeine and nicotine can affect muscle tension and the general state of alertness both in thinking and mechanical tasks.
One reported source in the literature mentioned that an athlete in the marathon had improved his performance by 7% by consuming the caffeine equivalent of one cup of coffee.
Aside from biological considerations society has a bearing on the consumption of these chemicals. My results at least contribute to the debate that at least on the surface they may have a use in task performance.
Evaluation.
In discussion among the class it emerged that all the individuals had consumed tea or coffee for breakfast. This leads to the immediate conclusion that this aspect of the experiment was not a fair test as we could not control how much they had taken, nor when they had taken it. Fortunately the investigation was conducted mid-morning which should have reduced the effects of any intakes considerably. As a wider issue the students all have differing body mass and presumably different tolerance to this chemical (chemicals) and therefore this wide set of variables needs more detailed focusing in future experiments.
In the design of the experiment one of the problems was that not all students cold be said to have waited half an hour before getting on with their second tasks, because of queuing. Although some attempt was made by the teacher to control the class in this respect, an element of guesswork was involved in telling members when to drink their sample.
The results have tended to show that gender itself may not be a variable (the blocks), although on this small sample one could not say this definitely. Also by and large this simple experiment has demonstrated a consistent but insignificant effect with respect to treatments. I.e. there is no significant difference in results performed after imbibing caffeine with respect to the control of no caffeine. This therefore casts doubt on the method’s usefulness. However given the fact that the results may be significant at the 1% level indicates that further work should be undertaken to separate out the effect of nicotine from caffeine. This should involve greater numbers of individuals in controlled conditions and a greater number of repeat experiments. One problem here is that young people should not be encouraged to smoke and theoretically most should not, leading to problems of sampling. Among heavy smokers it would be ironic if they needed to smoke in order to perform simple tasks well!
The problem of repeat runs needs to be looked at more carefully. repeat runs. This would have the effect of coaching or training the students to do better in the exercise. These effects may mask the effects or otherwise of the chemicals. It would require more research in this area, but replication of results should logically entail individuals performing the test, taking sample of caffeine, repeating the experiment, waiting for a suitable interval and then repeat the whole process. It may not be theoretically sound to replicate six runs before imbibing, and them repeating six runs after imbibing as the design of this experiment has heretofore been conducted.
In any given class situation the problem arises of standardization. It was not possible (and maybe not desirable in any event) for prior training to be given on how students were to approach the exercise. One can imagine and evidence from the data supports this that some students will take great care not to sound the bell and hence take a greater time to complete the task. Others may rush the task casually not caring how many mistakes they make. This difference in attitude may not be important to the averaging process but would be important if particular students changed their plan in between experiments.
Overall given these considerations and the results of the two-way anova and the ‘t’ tests, this experiment has been difficult to evaluate. There are many variable remaining to be isolated.
It would have been helpful to monitor some of the suggested effects of the chemical such as the pulse rate. This sort of analysis might help to analyze the results of the individuals involved, as heart rate is extremely variable among the population. A greater quantity of caffeine probably needs to be taken before the results will show a significant change.
