A controlled experiment on the effects of forced delay between computer interactions. Twenty subjects of varying experience used JOSS in solving a planning problem. Twelve were locked out between trials --i.e., after receiving a current set of results. The experimental findings call into question some common beliefs about man-computer interaction. Subjects with a 5-min lockout did better work in less time and used less computer time than those with free access. An 8-min lockout proved disruptive, especially to experienced users. Other findings suggest that self-imposed restraint can also improve problem solving efficiency, that users' acceptance of the system is not necessarily a valid predictor of system effectiveness, and that users were inaccurate in recalling their problem solving behavior. There was also evidence that some online users felt pressured by the system to interact prematurely. These findings should aid in evaluating interactive systems. (See also R-520, R-573, R-584, RM-6132.) 54 pp. Ref.