College students in 2 experiments learned a complex laboratory task, Space Fortress, in a context representative of pilot training. Experiment 1 contrasted massed (« = 23) and distributed (n = 22) intervals between practice lessons. Experiment 2 contrasted 25-min interlesson activities of task-relevant elaboration (n = 20) versus an arithmetic task (n = 20). Both experiments tested acquisition, retention, transfer from joystick to keyboard, and interference from a secondary tapping task. All tests favored the distributed group and the elaboration group. Advantages during acquisition

A training sequence on a complex video research task was distributed over 10 days or massed within two days. Measures of fatigue and confidence were taken. A final test battery given 1 week after acquisition consisted of retention tests, a test of resistance to interference, and a test of transfer. Trainees in the Distributed condition performed better throughout. Massed and Distributed trainees showed moderate levels of fatigue and did not differ from each other. Differences in confidence could not account for the results. Theories based on massing simple task acquisition within an hour are discussed as a framework for understanding and reducing suppression caused by massing complex tasks within days.