Date of Award

5-1-1984

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Psychology

Abstract

Caffeine is said to increase alertness and improve attention. However, the research which has examined the relationship between caffeine and attention has been atheoretical with respect to current theories of information processing. Therefore, the specific aspects of information processing that caffeine influences cannot be ascertained by the existing data. The purpose of the existing study was to examine the effect of caffeine on memory performance using a task that has theoretically and empirically discernable component processes. Specifically, the present study assessed whether caffeine selectively influences short or long term memory by examining subjects' immediate memory for word lists (cf. Glanzer & Cunitz, 1966). Furthermore, the word lists were presented at two different rates in order to examine whether caffeine influences the efficiency with which information is processed through the system.

One hundred and seventeen college students (60 females, 47 males) were divided into twelve groups of subjects. Four groups received 0 milligrams of caffeine per kilogram of their body weight, four groups received 2 mg/kg of caffeine, and four groups received 4 mg/kg of caffeine. Within each dose level, subjects were further divided according to their level of impulsivity and sex.

Subjects heard 8 word lists, 4 lists at a slow rate and 4 lists at a fast rate. Subjects heard one list at a time, followed immediately by an oral recall test.

The proportion of words recalled from the primacy (first 4 words), middle (middle 4 words), and recency (last 4 words) portion of each list was computed. A 3 (Caffeine) x 2 (Impulsivity) x 4 (Practice) x 2 (Rate) x 3 (Serial Position) ANOVA was computed separately for males and females. Standard significant main effects of practice, rate, and serial position were found along with a rate x serial position interaction for both males and females.

Most importantly, a significant caffeine x rate interaction was observed for females. At all three doses, recall was better at the slow rate than at the fast rate. No caffeine effects were observed at the fast rate, however, the 2 mg/kg and the 4 mg/kg dose impaired recall under the slow rate. There was a larger increment in performance during the slow rate at the 0 mg/kg dose as compared to the 2 mg/kg and the 4 mg/kg dose level. Thus, caffeine seemed to inhibit females' ability to benefit from the slow rate of presentation.

The primary result of the present study was that caffeine impaired recall for females. Caffeine reduced the ability of females to take advantage of the slow rate of presentation. The slow rate, relative to the fast rate, allows persons to more effectively rehearse items, consequently resulting in better recall (Broaie et al., 1975). It appears that under the caffeine conditions, females are not able to rehearse words as effeciently as possible. A caffeine x rate x serial position interaction was not observed and it is probable that caffeine is not affecting the strategy utilized in rehearsal. Therefore, caffeine may be affecting the efficiency with which information can be rehearsed. A more extensive manipulation of rate may help elucidate the viability of this interpretation.

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