The main purpose of the research reported in this document was to discover whether controlled experiments can be conducted on the relations between people and the complex computing systems which they use. Three increasingly complex experiments were designed to test the effect of varying delays of computer response on the number of commands issues per minute, as well as the total time needed to complete a task. The system used was a time-shared, on-line TX-2 computer and the Lincoln Reckoner, a subset of the programs in the executive system known as APEX. It was hoped that the experiments would not only further the knowledge of how people solve problems, but also aid in the design of new systems. The results indicate not only the feasibility of testing man-computer interaction, but also demonstrate more clearly the differences between the subjects' behavior in the various tasks in such indices of performance as net completion time and number of outputs. In addition, the gross completion time curves and output rate curves indicate that experiments large enough to produce stable curves would be feasible. Appendices, a reference list, diagrams, charts, tables and graphs are included in the document. (SH)