The effects of amitriptyline, trazodone and placebo on cognitive skills performance were examined in a group of 15 normal volunteers with a minimum age of 60. Each subject was behaviorally tested after single, acute treatments at weekly sessions using a battery of tasks measuring visual search, division of attention, tracking, critical tracking, rate of information processing, and vigilance. Amitriptyline, 50 mg, produced impairment on the vigilance task, the divided attention task and the critical tracking task. In addition, episodes of extended insensitivity to external stimuli similar to short-term sleep occurred. In contrast, trazodone exhibited impairment only on the critical tracking task. This study indicates that trazodone is less likely than amitriptyline to produce impairment of skills performance aspects of cognition.