Measurement and development of schedule-induced drinking in pigeons

Three food-deprived pigeons were exposed to fixed-interval (FI) schedules of grain presentation ranging in value from 15-sec to 4-min. A photocell arrangement located above the water cup recorded frequency, duration, conditional probability, and temporal location of drinking. Drinking developed at inter-food intervals of 2-min or 4-min, gradually increased in magnitude, and stabilized after a large number of experimental sessions. Two of the three pigeons showed substantial levels of water intake, and all birds developed typical patterns of adjunctive drinking in which bouts occurred either shortly after reinforcement, or within the first half of the inter-food interval. These data suggest that previous difficulties in extending the generality of schedule-induced drinking to pigeons may reflect failures to properly arrange an effective combination of procedural variables.