Display reinforcement in the Siamese fighting fish, Betta splendens: aggressive motivation or curiosity?

Fish were tested in a runway T-maze apparatus. The experiments compared performance (measured by swimming speed and percent choice correct) to a variety of stimuli in the goal box. The stimulus that evoked the most vigorous aggressive display (a live conspecific) supported the highest level of performance; a stimulus that evoked no display (a marble) failed to sustain operant behavior. Stimuli that induced some aggression, but also some escape (live nondisplaying fish), supported performance at reduced levels. These results implicate aggression and not curiosity as the primary motivating factor. They also show that the responsiveness of the stimulus is a critical aspect of reinforcement and that the level of performance is determined by escape tendencies as well as aggression. It is proposed that failure of a stimulus to provide appropriate feedback constitutes an aversive event.