The Effects of Caffeine on Coginitive Processing for Problem Solving

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The Huron University College Journal of Learning and Motivation Volume 48 Issue 1 Article 12 2010 The Effects of Caffeine on Coginitive Processing for Problem Solving David Ulbrych Follow this and

1 The Huron University College Journal of Learning and Motivation Volume 48 Issue 1 Article The Effects of Caffeine on Coginitive Processing for Problem Solving David Ulbrych Follow this and additional works at: Part of the Psychology Commons Recommended Citation Ulbrych, David (2010) "The Effects of Caffeine on Coginitive Processing for Problem Solving," The Huron University College Journal of Learning and Motivation: Vol. 48: Iss. 1, Article 12. Available at: This Article is brought to you for free and open access by the Psychology at Scholarship@Western. It has been accepted for inclusion in The Huron University College Journal of Learning and Motivation by an authorized administrator of Scholarship@Western. For more information, please contact kmarsha1@uwo.ca.

2 298 The effects of caffeine on cognitive processing for problem solving David Ulbrych Huron University College Caffeine affects general and cortical arousal (Aue, Arruda. Kass, and Stanny, 2009); this study examines the effects of caffeine on cognitive processing. Thirty-two participants were tested in the morning or afternoon and given 170ml of Diet Coke or Caffeine-free Diet Coke to consume, Eysenck Personality Inventory test to complete, and then an anagram sheet to complete that was timed. The time was collected for the data. The results showed no significant relation between performance in the caffeinated and decaffeinated conditions and no significemt interaction between time-of day and presenee-of eaffetner The implications of the results are discussed further. Caffeine is the world's most commonly-used drug for psychoactive purposes; it is consumed on average 70mg daily around the world. Caffeine is rapidly absorbed by the gastrointestinal tract, taking about 30 minutes to reach its highest level within the body. Meyer, Canzler, Giers, and Walther (1991) discuss how the half-life of caffeine is about 5 hours, however nicotine, and contraceptive pills greatly affect and change that. Caffeine affects peripheral and central nervous systems by blocking adenosine Ai and A2a receptors (Lesk and Womble, 2004). Ai and A2a receptors inhibit activity of the presynaptic and postsynaptic nerve cells, caffeine binds with these receptors and prevent inhibition thus increasing neural activity (Lesk and Womble, 2004). Aue, Arruda, Kass, and Stanny (2009) briefly mention how that caffeine is a stimulant that increases general and cortical arousal. Aue et al. (2009) studied the ability of sustaining high levels of focus and performance on long and repetitive tasks, which they termed as vigilance, and sought to

3 manipulate it. They used Continuous Performance Tasks to assess the levels of vigilance and used caffeine as one of the ways to manipulate the performance on the task; they tested the level of performance on two intervals, 1.5 minutes and 5.2 minutes. The task used was a point-tracking task in which the participants were asked to follow a white dot with a stylus on a computer screen. The participants were asked to drink a caffeinated or placebo drink and were then given energetic and tiredness scales from the Visual Analog Mood Scale (YAMS) (Aue et al., 2009). The participants were asked to wait 30 minutes for the caffeine to be metabolized; after the break they were given the point-tracking task to complete and then given the another YAMS test to complete. The results showed no significant difference between the two intervals and showed that caffeine did not affect the performance on the point-tracking task. Lesk and Womble (2004) studied caffeine and its effect on short-term plasticity (STP) specifically using tip of the tongue (TOT) responses. Lesk and Womble (2004) did two experiments, the first one was designed by having one hundred general knowledge questions that were answered by one word (the target). Two separate lists of ten prime words were constructed containing either 5 phonologically related and unrelated words to the target or all 10 unrelated. The participants were asked to take caffeine or placebo tablets and then wait 40 minutes for the caffeine to be metabolized (Lesk and Womble, 2004). Ten prime words were presented to the participants on a computer screen for 5 seconds and were asked to read them out loud. Lesk and Womble (2004) gave the participants a general knowledge question and were asked whether the answer was TOT, know, or don't know. If in the TOT state, participants were then given phonemes of the correct word as a way to check that they were in the TOT state for the

4 correct word (Lesk and Womble, 2004). Lesk and Womble (2004) found that in the first experiment, caffeine had a significant decrease of TOT corrects with the related condition and a significant increase in TOT corrects in the unrelated condition. Lesk and Womble (2004) conducted a second experiment that was similar to the first experiment except that both lists contained phonologically related words to the target, one had 2 or 3 related words and the other had 7 or 8 related words. The procedure was the same as in the first experiment and the results from the second experiment showed that caffeine increased the number of related words retrieved (Lesk and Womble, 2004). Lesk and Womble (2004) concluded that the effects of caffeine enhance STP for phonological retrieval This study built upon the two previous studies by examining how caffeine affects cognitive processing, specifically with problem-solving skills. This study used anagrams to further determine whether caffeine affects cognitive processing. The two different testing periods were to control for wakefulness alone and were also related to the wakefulness of introverts and extraverts at certain periods of the day. This study hypothesized that participants in the caffeinated condition would do better than participants in the decaffeinated condition. Another hypothesis was formed that there would be a significant interaction between time of day and presence of caffeine. Method Participants The participants were collected from Huron University College varying in age fi-om 17 to 22 and came from various areas of academic study. Thirty-three participated

5 in the study which had Seventeen women and fifteen men, the majority were friends of the experimenter. All come from a similar socio-economical status given the demographic of the population of the college. Materials This study used two litre bottles of Diet Coke and caffeine-free Diet Coke that can be purchased from any grocery store. The liquid was given to the participants in No Name brand 173ml Styrofoam cups and poured out during the study. The participants were given an Eysenck Personality Inventory test that was copied from the Department of Psychology's database of tests. Lastly the participants were given a page of 10 anagrams (Apendix A), four letters in length, which were taken from the "Everyday Vocabulary Anagrams" website (Kelly and Kelly, 1998) and arranged in alphabetical order. A Timex watch and BlackBerry were used as stopwatches to keep track of time for the participants while they performed the anagram task. Procedure The study was conducted at two times periods, an AM period that was from 9:30 to 11:30, and a PM period that was from 1:30 to 3:30. Within each time period, participants were alternately divided into the caffeinated condition or the decaffeinated condition. Participants were tested in various classrooms and the Student Activity Centre. After given a letter of information and signing the consent form, they were asked to drink from a Styrofoam cup that contained 170ml of either Diet Coke or caffeine-free Diet Coke. The liquid was poured directly into the cup from the two litre bottles while the

6 participants read the letter of information and signed the consent form. The participants were asked to drink the entire contents of the cup and then fill out an Eysenck Personality Inventory test; the test contained fourty-one questions about personality and behaviour and took between ten and fifteen minutes to complete. The purpose of the test was to allow time for the caffeine or control to be metabolized by the body and had no further use afterwards. Once completed the test, the participants were given a sheet of paper that contained ten anagrams and asked to form new words fi-om the existing ones while being timed. The time it took to complete the anagrams was recorded and analyzed below. One participant was removed from the data due to not completing the anagram task. Afterwards the participants were given a debriefing statement informing them of the purpose of the study and providing background information to the study. Results A 2 X 2 between-subjects ANOVA was conducted with time taken to complete anagrams as the dependant variable and time of day (AM or PM) and presence of caffeine (caffeinated or decaffeinated Coke) as the independent variables (Appendix B). It was predicted there would be a significant interaction between time of day and presence of caffeine. The results indicated that there was no significance, F(l,27) = 1.637,p>.05. It was also hypothesized that participants in the caffeinated condition would perform better than participants in the decaffeinated condition. As shown in figure 1, it was found that the decaffeinated condition (M = 225 s, SD = s) outperformed the

7 c OJ AM time of Day PM f/gure 1. Interation between time of day arid presence of calfeine. The dottdd line shows the mean times of the participants in the decaffeinated condition and the solid line shows the mean times of the participants in the caffeinated corldition. u> s

8 caffeinated condition (M = 183 s, SD = s), though not significantly, t(29) =.840, p >.05. Discussion As seen in the results above, there is no significant interaction between time of day and presence of caffeine. The results also show an interesting conclusion that the decaffeinated condition performed better on the anagrams than the caffeinated condition, however they were insignificant. These results show that caffeine has no effect on cognitive processing. Aue et al. (2009) discussed in their article that caffeine effects cortical arousal and tested to see whether it would affect performance and focus on extended tasks. Lesk and Womble (2004) tested caffeine and its effects on short term plasticity in relation to tip of the tongue responses. Both studies found their data to be insignificant. This study further examines the effect of caffeine on cognitive processing, specifically related to problem solving. This study also found no significant relations or interactions. Aue et al. (2009) suggested the caffeine is more effective on cognition when there is already lower cortical arousal; thus if participants were sleep deprived then results would have been different. There were a few problems within the study including caffeine that are harder to control, namely the half-life and how some pharmaceuticals affect caffeine. The half-life of caffeine is five hours, so if a participant had ingested caffeine in the morning and were tested in the afternoon then the residual coffee left in their body could have affected the results of the study. Other pharmaceuticals. Like contraceptivepills, affect the half-life of

9 caffeine by extending it to 5-10 hours; therefore the female participants may have had more caffeine within their body at the begirming of the study if they had caffeine that day. There was also a problem with the way that cognitive processing was measured and how the anagrams were created. There was great variation between participants at how quickly the anagrams were completed, which shows that anagrams may not be the best way to test cognitive processing. The anagram sheet contained existing English words that had. to reformed, into new words; this may have impacted the study because of the difficulty of forming new words from existing words as opposed to scrambled letters. The controls in this experiment were blind administering of drink, administering of the Eysenck Personality Inventory test, and random sampling of introverts and extraverts within the AM and PM conditions. The participants were uninformed whether they received a caffeinated or decaffeinated drink prior to the test, this was to ensure that participants didnot presuppose whalcondition they belonged to and act accordingly. The administering of the Eysenck Personality Inventory test was to ensure that the caffeine had begun to metabolize by the time the participants were given the anagram sheet. The random sampling of introverts and extraverts. within the raffpinatph and decaffeinated condition was to control for the fact that introverts perform better with caffeine in the afternoon and extraverts perform better in the morning. This way through random sampling, the participants would have been equally spread out between the two conditions. This experiment tested and expanded upon both Aue et al.'s study and Lesk's and Womble's study by examining the effects of caffeine on cognitive processing and its interaction with time of day. The results showed that there was no significant relation

10 between the caffeinated and decaffeinated condition and no significant interaction between time of day and presence of caffeine. However due to the materials used to test the e.xperiment, like the anagrams, more research could be done to better understand how caffeine affects the brain.

11 References Aue, W. R, Arruda, J. E., Kass, S. J. & Stanny, C. J. (2009). Cyclic variations in sustained human performance. Brain and Cognition, 71, Lesk, E. V. & Womble, S. P. (2004) Caffeine, priming, and tip of the tongue: Evidence for plasticity in the phonological system. Behavioural Neuroscience, 118, Meyer, F. P., Canzler, E., Giers, H., and Walther H. (1991). Time course of inhibition of caffeine elimination in response to the oral depot contraceptive agent deposiston: Hormonal contraceptives and caffeine elimination. Zentralbl Gynakol, 113(6), Abstract obtained from PubMed database.

12 Appendix A Anagrams The objective is to rearrange the letters of the existing word to form a new word and write the answer in the line beside. Example: cafe - face Aide Bear Chin Cork Dear Evil Fade Gods Hate Item

13 Appendix B Analysis of Variance for Time of Day and Presence of Caffeine Source Sum of Squares df v' F Sig. AM or PM Caff or Decaff AM or PM* Caff or Decaff Error Total

L-Theanine Clinical Studies

ALL A B C D E F G I K L M N O P Q R S T V Z L-Theanine Clinical Studies Nippon Nogei Kagakukaishi. Kobayashi K, et al. Effects of L-theanine on the release of a- brain waves in human volunteers. 1998;72(2):153-7.