Rewarding properties of visual stimuli.

The behavioral functions of rewards comprise the induction of learning and approach behavior. Rewards are not only related to vegetative states of hunger, thirst and reproduction but may also consist of visual stimuli. The present experiment tested the reward potential of different types of still and moving pictures in three operant tasks involving key press, touch of computer monitor and choice behavior in a laboratory environment. We found that all tested visual stimuli induced approach behavior in all three tasks, and that action movies sustained consistently higher rates of responding compared to changing still pictures, which were more effective than constant still pictures. These results demonstrate that visual stimuli can serve as positive reinforcers for operant reactions of animals in controlled laboratory settings. In particular, the coherently animated visual stimuli of movies have considerable reward potential. These observations would allow similar forms of visual rewards to be used for neurophysiological investigations of mechanisms related to non-vegetative rewards.