Topics: Caffeine, Statistical significance, Coca-Cola Pages: 13 (2800 words) Published: October 26, 2014
The Effects of Caffeine 1

The Effects of Caffeine and Placebo on Computer Typing Skills St. Olaf College
May 14, 2009

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This study examined the effects of caffeinated versus caffeine-free CocaCola and Diet Coke on the speed, accuracy, error and words per minute of typing skills. 30 undergraduate students participated in the experiment for academic credit for an introductory to psychology class. The participants consumed their choice of soda and were asked to wait 30 minutes for the caffeine to take effect before conducting the typing test. The Speed Typing Test 2000 was used to perform the actual test as well as used to collect the data for the dependent variables. The results showed no statistical difference (p= .1-.8) in any of the facets of performance across conditions, which would lend support to the hypothesis that a placebo effect took effect. A post hoc control group was added to the experiment. The 10 participants in the control group were not part of the initial two experiments, and completed the typing test without consumption of either beverage. The results from the comparison of the condition groups showed no difference in performance in any of the dependent measures, undermining the hypothesis of the placebo effect. However a control was not put in place to ensure that participants did not consume caffeine before the study. A series of limitations and confounds also present themselves.

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The Effects of Caffeine and Placebo on Computer Typing Skills Caffeine is one of the most highly consumed psychostimulants to be used in everyday life (James & Rogers, 2005). Much research has been conducted into the effects of caffeine on the body’s physiological responses and reactions. Past studies have also looked at the placebo effect of caffeine. A study conducted by Flaten and Blumenthal (1999) examined the physiological responses to caffeine related stimuli. The results of the study found a placebo effect for coffee, a substance highly related to caffeine. This study, and many others, provide support that caffeine can produce a repeatable and reliable placebo effect. This study did not examine the physiological effects of caffeine, however, instead examining the effects of caffeine on motor tasks. Caffeine has been found to increase attention, reaction times, vigilance, and mood (Frewer & Lader, 1991; Regina et al., 1974; Smith, 2002). Previous studies have found that caffeine can increase reaction time in situations in which a motor response was required, such as key tapping (Frewer & Lader, 1991). One study, done by Fillmore and VogelSprott (1992) found that a motor response, in this case computerized tracking, can produce a placebo effect. The study looked at caffeine expectancy rates on performance. The findings showed that participants who were explicitly informed that caffeine improved performance, did so. The participants who were informed that research had shown that caffeine was inhibitory on performance, performed at a lower rate than the group who was given no cue for expectancy. The researchers concluded that a placebo effect can be examined in motor tasks according to the type of expectancy of the drug.

The intent of the current study was to examine the placebo effect in the psychomotor task of typing. Very little research has been conducted on the effects of caffeine on typing. One study was found was by Hollingworth in 1912. This was a case study of a single 38-year-old secretary and the effect of caffeine on the speed and accuracy of typewriting. The study encompassed four weeks in which the participant received varied levels of caffeine (1-6 grains) along with control days where she received no caffeine. The results showed an increase in

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performance with a lower amount of caffeine, but an inhibited performance with a higher amount of caffeine. This finding provides support that caffeine can enhance...

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responses: An experimental model of the placebo effect
Frewer, L.J., & Lader, M. (1991). The effects of caffeine on two computerized tests of attention
and vigilance
Hollingworth, H.L. (1912). The influence of caffeine on the speed and quality of performance in
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ability patterns
James, J.E., & Rogers, P.J. (2005). Effects of caffeine on performance and mood: Withdrawal
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Nicholson, K.G., & Kimura, D. (1996). Sex differences for speech and manual skill. Perceptual
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