Studies in Light Reinforced Behavior: II. Effect of Food Deprivation and Stress
A year ago the senior author reported a series of experiments (6) which demonstrated two phenomena. (a ) Hungry rats will operate a lever with considerable gusto when the only identifiable incentive is light-onset (switching on a 6-v, 5.2 -cps lamp ) . ( b ) If Ss are placed in an illuminated chamber and the lever in the apparatus is made to turn off a light, the lever pressing frequency falls below that recorded under condition (a) and is only slightly above the lever pressing frequency recorded under an "operant test," i.e., where no after effect attends a lever press. These results, taken together, make the interpretation by Girdner (1 ), Marx, et al. ( 11 ), and Kling, et al, (9) that the reinforcing effect of light-onset is rooted in a "curiosity" or "exploratory" drive difficult to sustain, since it could be argued that light-offset also satisfies curiosity and exploratory tendencies. Rather than setting up a counter-hypothesis which would offer an alternative motivational basis for this behavior, we have chosen to inquire further into the incentive properties of light, as well as examine some of the conditions which increase or suppress the incentive and reinforcing properties of this stimulus. In the present set of experiments two questions are raised. (a) Does the degree of hunger, as determined by the feeding-fasting regimen, affect the incentive properties of light? (b) To what extent may the incentive properties of light be suppressed?