The Effects of Caffeine and Sugar on the Memorization of Word Lists
Sponsored by Missouri Western State University Sponsored by a grant from the National Science Foundation DUE-97-51113
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The proper APA Style reference for this manuscript is:
BODDE, B. L. (2004). The Effects of Caffeine and Sugar on the Memorization of Word Lists. National Undergraduate Research Clearinghouse, 7. Available online at Retrieved April 25, 2017 .

The Effects of Caffeine and Sugar on the Memorization of Word Lists
Missouri Western State University DEPARTMENT OF

Sponsored by: Brian Cronk (
Caffeine is used on a daily basis by many people. Caffeine is a stimulant that helps create alertness. Sugar is a natural sucrose that is consumed daily also. This study will look at the effects of caffeine and sugar on memory of word lists.Participants signed up for one of seven times. In all, there were 47 participants. Each participant received a cup of coffee upon arrival. After drinking the coffee, they waited five minutes. After the five minutes, the participants were shown a list of 21 words for one minute. After that minute, they were given two minutes to recall as many words as possible. After the two minutes, they were released with the knowledge of what type of coffee they drank.The results showed that they were no significant main effects for either caffeine, sugar, or any interaction of the two. These results do not support the hypothesis of this experiment.

In today’s society caffeine and sugar are used daily to help people get through the day. However, is it really helping them? Many studies have already been done to see the effects on caffeine and memory. This study will also look at the effects of sugar on memory as well as caffeine. Caffeine is a central nervous system sedative that helps create alertness (Jung, Yeo, & Gangestad, 2000). It is used everyday by many Americans, with an average dosage of four mg/kg, equivalent to two cups of coffee. Sugar is also used everyday by Americans. Sugar is also known as sucrose and is a carbohydrate that naturally occurs in fruits and vegetables. Sweet Thing is an artificial sweetener that contains aspartame. Other variables have been looked at with caffeine and memory. According to Erikson, Hager, et al. (1985) how caffeine effects an individual depends on if a person is an introvert or an extrovert. With introverts, caffeine has shown to increase performance on memory tests when given in little dosages (0 and 2 mg/kg), but decreases performance when given at higher dosages (2 and 4 mg/kg). When it comes to extroverts, though, their performance increased along with the dosage levels. Kelemen and Creeley (2003) saw an effect with the time of day the caffeine was used. Low-impulsive people are impaired in the morning and high-impulsive people are aroused in the morning. They hypothesized that low-impulsive people are more aroused in the morning and it wears down as the day goes by.Revelle et al believes that caffeine affects the processing of information, but it is not yet determined which components or stages are actually being affected (1980, as cited in Erikson, Hager, et al, 1985). Another two outside variables affecting word lists are the primacy and the recency effects. These effects, respectively, help to influence the recall of words from the beginning of the list and at the bottom of the list.Another variable that was looked at was attention with memory. Kelemen and Creeley (2001) saw that the human attention system was multifaceted so they devised several attention tasks that were sensitive to caffeine positively. Some previous studies have shown that caffeine can improve memory that has been delayed.Kelemen and Creeley (2001) also studied whether caffeine influenced metamemory with memory. Metamemory is the monitoring and controlling of memory. Metamemory is sometimes described as “what you know about what you know” (Kelemen & Creeley, 2003). One way of measuring metamemory is with the use of judgments of learning (JOLs). JOLs are often referred to the likelihood of future recall. Kelemen and Creeley (2001) found that caffeine had no effects on recall or JOLs. They did find that recall of different items was affected selectively, which then created misrepresentation metamemory accuracy. There is also some subject bias with metamemory, which is influenced by individual’s beliefs of what they think the research wants.The purpose of this study is to find the effects of caffeine and sugar on memory of a word list. The hypothesis is that caffeine will improve memory but the sugar will have negative affects on memory. The independent variables will be whether the participants receive Regular or Decaffeinated coffee and whether they receive sugar or Sweet Thing. The dependent variable will be the number of words remembered from the list.


Data was collected from 47 participants. These Participants were students in General Psychology, Intermediate Psychology or Lifespan and Development. They signed up in hopes to receive extra credit from their professors, if they participated. They were informed about the possibility of receiving caffeine, sugar, and or aspartame sweetener, when they signed up.

Folger’s Regular and Decaffeinated coffees were used as the caffeine. Regular table sugar and Sweet Thing, a sugar substitute with aspartame sweetener, were also used. Best Choice brand Non- Dairy Creamer was added to the coffee to help deter the taste for normal coffee drinkers. In each cup, there was six ounces of water, two teaspoons of instant coffee (twice as much as what is called for), either two packets of Sweet Thing (measuring one teaspoon) or one teaspoon of sugar, and one tablespoon of non-dairy creamer. The amount of caffeine in the Regular coffee was 130mg. The amount of caffeine in the decaffeinated coffee was 4mg. There were four different colored cups, red, blue, white, and clear, used to decipher for type of coffee being served. There was also a graded word list with 21 words used for the memorization test (Appendix).

The participants came to a designated room at the times they signed for. There were seven different sessions to accommodate the participants. The coffee was pre-made and put into the designated cup before the participants arrived. The four types of coffee were: Regular coffee with Sweet Thing, Regular coffee with table sugar, Decaffeinated coffee with Sweet Thing, and Decaffeinated coffee with table sugar. The participants were told to choose a cup of coffee, making it their choice of which cup they had. The coffee was ingested. While waiting, answer sheets were passed around the room, along with a five-question survey about their normal caffeine consumption. They were asked to circle the color of their cup at the top of their answer sheet. After the five minutes were up, the participants were instructed that they would be shown a list of 21 words for one minute. They would then have two minutes to recall as many words as possible. They were also told not to write anything until told to do so. After the two minutes were up, the participants were told what they had to drink and why the experiment was being done.

A 2 (coffee) x 2 (sugar) between-subjects factorial ANOVA was calculated comparing the word list memory test scores for subjects who had either a combination of sugar or sweetener and regular or decaffeinated coffee. The main effect of the sugar was not significant (F(1,43) = .030, p> .05). The main effect of the regular coffee (caffeine) was also not significant (F(1,43) = 1.413, >.05). Finally, the interaction was also not significant (F(1,43) = .576, >.05). Thus, it appears that neither the sugar nor the caffeine has any significant effect on word list memory tests.

The purpose of this experiment was to see if caffeine and sugar consumption affected the amount of words remembered on a memory test. According to the results, there are no significant main effects from caffeine or sugar on the memory of word lists. Although, the caffeine groups did better than the no caffeine groups overall (Figure 1), the difference was not found to be significant. The effects of the sugar seemed to interact with caffeine such that the presence of both reduced the benefits of caffeine. Yet, the interaction was not significant. These results are consistent with the hypothesis of caffeine with sweetener doing better overall, but there is not enough significant evidence though to accept the hypothesis. According to Revelle et al (1980, as cited in Erikson, Hager, et al, 1985), believes that caffeine affects the processing of information. This study doesn’t seem to agree. There were no significant main effects of either caffeine or sugar on the amount of words remembered by the subjects.The reasons for the findings being found not significant are unknown. What is known, however, is that there was not enough power. Some explanations are that there was enough caffeine and or sugar/sweetener used, not enough time allotted between consumption and testing or the fact that the number of subjects was considerably low.

Erikson, G. C., et al. (1985). The effects of caffeine on memory for word-lists. Physiology & Behavior, 35, 47-51.Jung, R. E., Yeo, R. A., & Gangestad, S. W. (2000). Developmental instability predicts individual variation in verbal memory skill after caffeine ingestion. Neuropsychiatry, Neuropsychology, and Behavioral Neurology, 13, 195-198.Kelemen, W. L. & Creeley, C. E. (2003). State- Dependent memory effects using caffeine and placebo do not extend to metamemory. Journal of General Psychology, 130, 70-87.Kelemen, W. L. & Creely, C. E. (2001). Caffeine (4mg/kg) influences sustained attention and delayed free recall but not memory predictions. Human Psychopharmacology: Clinical & Experimental, 16, 309-319.


Figure 1- Mean Memory Scores

Submitted 12/7/2004 12:57:16 PM
Last Edited 12/7/2004 1:19:16 PM
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