Download Article Summary Assignment - University of Puget Sound

Article Summary Assignment
TCSIG 330: Inquiry and Research in the Social Sciences
University of Washington, Tacoma
Professor Christopher Jones
Fall 2005
Christina Springer 0533820
Ryan, L., Hatfield, C., & Hofstetter, M. (2002). Caffeine reduces time-of-day effects on memory
performance in older adults. Psychological Science, 13, 68-71.
Research has shown that as people age their daily peak performance time shifts from
afternoon to morning. In addition, research has also shown that during this peak performance
time cognitive abilities are at their maximum potential. Unfortunately, the previous studies
exploring the time-of-day effect on the cognitive abilities of aging adults have only tested for
false recognition. Therefore, Ryan, Hatfield, and Hofstetter (2002) decided to expand this
knowledge by analyzing multiple cognitive abilities of aging adults in the morning and the
afternoon. They hypothesized that the time of day would negatively affect afternoon
performance of multiple memory and learning abilities in aging adults who preferred mornings.
Also, the researchers hypothesized that reduction in physiological arousal due to circadian
rhythm cycles was causing this time-of-day effect; therefore, they predicted that using a
physiological stimulant (they chose caffeine because it takes effect quickly) would reduce
cognitive decline in the afternoon.
Ryan et al. recruited single, active seniors over age 65 through newspaper advertisements
to participate in their study. They screened the respondents for daily caffeine intake, peak
performance time, and cognitive impairments (such as mental disorders and substance abuse)
and chose 40 persons who ingested caffeine daily, had morning peak performance times, and did
not have any known cognitive impairments. They then randomly assigned the participants into
two groups: they would receive either Starbucks house-blend regular or decaffeinated coffee.
(They did not know which coffee they would receive; indeed, when they were asked afterwards
which type they thought they had drank, most participants replied that they had drank both.)
One-half hour after the participants had drank their coffee, they were then administered the
California Verbal Learning Test (CVLT), which measures four aspects of memory: immediate,
short-, and long-delay free recall as well as yes/no recognition. The participants were tested both
at eight o’clock in the morning and four o’clock in the afternoon, with a delay of five to 11 days
in between tests so that they would not be able to easily remember their first testing.
The data supported both of the researchers’ hypotheses. First, the time of day did affect
multiple aspects of memory and learning in the senior participants: along with false recognition,
the data showed a decline in their ability for long-delay free recall and yes/no recognition in the
afternoon. However, time of day had no effect on their ability for either immediate or short-delay
free recall. Second, the time-of-day effect was caused by a decrease in physiological arousal
because a physiological stimulant (caffeine) did in fact reduce the time-of-day effect. Indeed, the
participants who drank regular coffee performed equally well on the CVLT in both the morning
and the afternoon; conversely, those who drank decaffeinated coffee showed their regular decline
in the afternoon. Ryan et al. believe that this physiological decline leads to attention deficits that,
in turn, reduce cognitive abilities. This information is particularly important for researchers
studying changes in cognitive ability in aging adults because they may be finding inaccurate
cognitive declines in their participants when testing occurs in the afternoon.