This study asked whether the concurrent reinforcement of behavioral variability facilitates learning to emit a difficult target response. Sixty students repeatedly pressed sequences of keys, with an originally infrequently occurring target sequence consistently being followed by positive feedback. Three conditions differed in the feedback given to non-target sequences: concurrent positive feedback presented contingent on response variability, positive feedback presented non-contingently, or no reinforcement for any non-target responses (control condition). Contrary to the result of analogous rat studies, if anything, the participants in the control condition more readily learned to emit the target sequence than did the subjects in each of the other two conditions. It is argued that these contradictory findings are primarily caused by procedural differences, such as differences in the density of the reinforcement schedule applied to non-target behavior, rather than reflecting a true species difference.