The experiment was designed to study the effect of personal control, operationalized in terms of choice between a more demanding and a less demanding task, on persons with different levels of reactivity. Subjects were randomly assigned and individually tested in a 2 (High reactivity/Low reactivity) × 2 (Low rate of stimulus presentation/ High rate of stimulus presentation) × 2 (Choice/No Choice) factorial experiment with 15 subjects per condition. The two principal dependent measures were the total number of correct responses in a serial RT task and the post-task levels of anxiety, anger, and curiosity. The major finding was that while the availability of control had a positive effect on both task performance and affect, its role was situation-specific, i.e. limited to the difficult task. Most probably the availability of control masks the variability of reaction due to individual differences in reactivity. However, high-reactives are still left with the residual stress of unresolved emotions.