Faculty Bibliography

This study investigated the hypothesis that age differences in memory performance may be influenced by stereotype threat associated with negative cultural beliefs about the impact of aging on memory. Recall was examined in 48 young and 48 older adults under conditions varying in the degree of induced threat. Conditions that maximize threat resulted in lower performance in older adults relative to both younger adults and to older adults who did not experience threat. The degree to which threat affected older adults' performance increased along with the value that these individuals placed on their memory ability. Older adults' memory performance across experimental conditions was observed to covary with degree of activation of the negative aging stereotype, providing support for the hypothesized relationship between stereotype activation and performance. Finally, stereotype threat also influenced mnemonic strategy use, which in turn partially mediated the impact of threat on recall. These results emphasize the important role played by contextual factors in determining age differences in memory performance.

The present article provides a brief review of the human and animal literature that has investigated the relationship between fitness training and brain and cognitive function. The animal research clearly suggests that improvements in fitness can lead to both morphological and functional changes in the brains of older animals. Results of a recent meta-analysis suggest that fitness training can also have beneficial effects on human cognition, particularly on tasks requiring executive control processing. These effects are also moderated by a number of factors, including the proportion of men and women in the intervention studies, the length of training sessions, the age of the participants, and the combination of fitness training regimes. The article also discusses preliminary results that link, for the first time, fitness training and differences in human brain structure and function. Finally, we discuss the important issue of participant adherence to fitness training programs and the factors that influence fitness participation.

While limited research is available, evidence indicates that physical and mental activity influence the aging process. Human data show that executive functions of the type associated with frontal lobe and hippocampal regions of the brain may be selectively maintained or enhanced in humans with higher levels of fitness. Similarly enhanced performance is observed in aged animals exposed to elevated physical and mental demand and it appears that the vascular component of the brain response may be driven by physical activity whereas the neuronal component may reflect learning. Recent results have implicated neurogenesis, at least in the hippocampus, as a component of the brain response to exercise, with learning enhancing survival of these neurons. Non-neuronal tissues also respond to experience in the mature brain, indicating that the brain reflects both its recent and its longer history of experience. Preliminary measures of brain function hold promise of increased interaction between human and animal researchers and a better understanding of the substrates of experience effects on behavioral performance in aging.

We briefly review the extant human and animal literature on the influence of fitness training on brain, cognition and performance. The animal research provides clear support for neurochemical and structural changes in brain with fitness training. The human literature suggests reliable but process specific changes in cognition with fitness training for young and old adults. We describe a research program which examines the influence of aerobic fitness training on the functional activity of the human using event-related functional magnetic resonance imaging, of humans in fitness interventions.

Four experiments investigated the conditions in which people use a prototypic event sequence to comprehend a situation-specific sequence of events. Results of Experiment 1 confirmed Trafimow and Wyer's (1993) findings that when participants use a prototype (e.g., a cultural script) to comprehend a new sequence of events concerning a hypothetical person, events that are thematically unrelated to the prototype facilitate the recall of prototypic ones. When participants do not employ a prototype, however, thematically unrelated events interfere with the recall of the prototypic ones. These findings establish a criterion for determining whether prototypes are used as a basis for comprehending an event sequence. Experiment 2 showed that the formation and use of a prototype to comprehend a novel event sequence increases with the number of exemplars to which persons have been exposed before the sequence is encountered. However, Experiments 3 and 4 indicated that people often do not use prototypes to interpret sequences of behaviors that they imagine either themselves or a well-known other performing. This is true even though they personally perform the sequence of behaviors on a daily basis and even though a prototypic representation of the event sequence exists in memory.

The instructions for most explicit memory tests use language that emphasizes the memorial component of the task. This language may put older adults at a disadvantage relative to younger adults because older adults believe that their memories have deteriorated. Consequently, typical explicit memory tests may overestimate age-related decline in cognitive performance. In 2 experiments, older and younger adults performed a memory test on newly learned trivia. In both experiments, age differences were obtained when the instructions emphasized the memory component of the task (memory emphasis) but not when the instructions did not emphasize memory (memory neutral). These findings suggest that aspects of the testing situation. such as experimental instructions, may exaggerate age differences in memory performance and need to be considered when designing studies investigating age differences in memory.