Two experiments demonstrated verbal conditioning with a complex reinforcement contingency that S was unable to identify. The unique nature of the contingency and a simple multiple-choice postexperimental questionnaire provided an improved method for determining that S did not know the contingency. Responses identified as critical by S were higher in frequency whether they were or were not reinforced, and critical responses not identified were used with similar frequency. The S's identification of a response, whether correct or not, was a sufficient condition (pseudo-conditioning), but was not a necessary condition for greater frequency. It was suggested that S may be problem-solving in verbal conditioning, and correct identification of the reinforcement contingency is equivalent to “awareness.” A complex reinforcement contingency eliminated problem solution, i.e., afforded a control of awareness. Such complex contingencies were recommended for use when problem solution is not desired, and were recommended as part of an approach to the study of reinforcement effects upon problem-solving.