A patient had seizures while playing chess or cards or when filling out complex forms, doing complex mathematical problems, and during certain parts of the neuropsychological testing. Seizures were myoclonic and accompanied and electroencephalographic dysrhythmia of the atypical spike and wave type. Evoked seizures were not related to visual, tactile, or auditory stimuli or clues. In chess, seizures occurred when he was on the defense and threatened. Simple decision making or physiologic stress did not evoke seizures nor did nonsequential decision making under verbal pressure. Evoking factors were complex decision making in a sequential fashion and with an element of stress or concern regarding the outcome of the decision making. Stimulus was usually nonverbal. Three major factors--decision complexity, sequential factor, and related stress or concern--may have some reciprocal relationships.