This paper describes an experiment concerned with the operation of discriminatory processes subsequent to an individual's overt choice response and how these may be affected by extrinsic stimulus information. The experiment used subhuman primates and was conducted within the simultaneous two-choice visual discrimination paradigm. The major results of the experiment indicated that: (1) learning performance may be significantly interfered with by irrelevant postresponse stimulus information, and (2) this interference is primarily associated with the presentation of irrelevant information subsequent to nonreinforced choice responses. The results are discussed in terms of the relation between the occurrence of reinforcement and the operation of memory storage processes.