A cross-sectional examination of age and physical activity on performance and event-related brain potentials in a task switching paradigm Charles H. Hillman, Arthur F. Kramer * , Artem V. Belopolsky, Darin P. Smith Beckman Institute, University of Illinois, 405 North Mathews Avenue, Urbana, Illinois 61801, USA Received 11 January 2005; accepted 8 April 2005 Abstract Younger and older physically active and sedentary adults participated in a task switching paradigm in which they performed a task repeatedly or switched between two different tasks, while measures of response speed, response accuracy, P3 amplitude, and P3 latency were recorded. Overall, response times were faster and midline P3 amplitudes were larger for the active than for the sedentary participants. P3 latencies discriminated between active and sedentary individuals on trials in which multiple task sets were maintained in memory and task switches occurred unpredictably but not in blocks of trials in which a single task was repeatedly performed. Results are discussed in terms of the specificity and generality of physical activity effects on cognition. D 2005 Elsevier B.V. All rights reserved. Keywords: Exercise; Executive control; P3; ERP; Aging; Fitness Over the past several decades there has been an increasing interest in the influence of physical activity and in particular aerobic exercise, on human cognition. Early studies of this relationship often examined the influence of physical activity differences, for both younger and older adults, on the performance of simple and choice reaction time (RT) tasks. For example, Spirduso and Clifford (1978) found that older physically active adults were significantly faster on a variety of different RT and movement time tasks than older sedentary adults. These initial observations were confirmed in numerous subsequent studies of cross-sectional physical activity diffe- rences on the performance and cognition of older adults (see Etnier et al., 1997 for a review). The literature that has examined whether younger adults show similar physical activity benefits on the performance of cognitive tasks has been more equivocal (Lupinacci et al., 1993; Rikli and Busch, 1986), perhaps as a result of the generally moderate to high activity levels of younger adults in the cohorts that have been studied. The relatively strong relationship between physical activity and cognition, particularly with older adults, has not always been observed with randomized clinical trials in which an aerobic training group is compared to a non-aerobic control group. However, a number of intervention studies have reported improvements in particular aspects of cognition with physical activity training (see Colcombe and Kramer, 2003 for a review of this literature). Interpretation of the results from these studies is complicated by differences in the length, intensity, and type of training regimens, the age, health, and beginning and ending cardiovascular fitness levels of the study participants, the methods used for the assessment of cardiore- spiratory fitness, and the tasks used to index perceptual, cognitive, and motor function improvements. Given the relatively small sample of individuals who have participated in each of these studies, Colcombe and Kramer (2003) performed a meta-analysis on the randomized clinical studies of physical activity effects on cognition in an effort to determine whether (a) a reliable physical activity effect could be discerned with the additional power that is gained when aggregating data across studies and (b) if so, which factors moderate the effects of physical activity on cognition. Several interesting and potentially important results were obtained. First, a clear and significant effect of aerobic exercise training was found. Second, aerobic exercise training had both general and selective effects on cognitive function. Although physical activity effects were observed across a wide variety of tasks and cognitive processes, the effects were largest for those tasks 0167-8760/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ijpsycho.2005.04.009 * Corresponding author. E-mail address: akramer@cyrus.psych.uluc.ac (A.F. Kramer). International Journal of Psychophysiology 59 (2006) 30 – 39 www.elsevier.com/locate/ijpsycho