Characteristics of differential inhibition during selection between food-related and aversive responses.

The same stimulus (a flash of light at a frequency of 6 Hz) was used in dogs to develop a food-related conditioned reflex reinforced by attractive food and an aversive conditioned reflex (avoidance/escape from paw stimulation) and differential inhibition to it (unavoidable series). This was followed by alternate experiments with selection of reinforcement and use of a differential stimulus (at a frequency of 0.6 Hz). In both series of experiments, dogs showed changes in food-related excitability (hunger, saturation). The numbers of investigative responses arising in response to the differential and positive conditioned stimuli and their latent periods were recorded. In conditions allowing selection (with electrodes on the paw and a pedal before the animal), dogs were found to differ in the extent to which one of these motivations dominated. Differential inhibition was less complete in those no-choice series in which the dominant motivation was used. In conditions allowing selection between the food-related and aversive reactions, responses to the differential stimulus depended on the balance between these motivations: the food-related motivation dominated after two days of starvation, while the aversive motivation dominated after satiation.