The development of water drinking on a dry-food free-reinforcement schedule

Abstract

Rats were given a food pellet every 60 sec., not contingent on operant responding. All rats developed over days a pattern of prolonged water drinKIng !allowing delivery of food pellets. One of the rats, whose operantlevel lever pressing was recorded concurrently with licking, developed a complex pattern of drinking and bar pressing which persisted even after a 5-sec. delay of reinforcement for bar presses was introduced. Problem Several investigators have reported unusual frequ€mcies and quantities of water drinking by rats maintained on interval reinforcement schedules for food. VI (Clark, 1962;Falk, 1961Falk, , 1964, DRL (Segal & Holloway, 1963; Segal & Deadwyler, 1964b) and freereinforcement (Segal & Deadwyler, 1964a) schedules produce the polydipsia, liquid as well as dry food reinforcers are effective (Falk, 1964), and alcohol solutions (Lester, 1961) as well as water are drunk. The aims of the present experiments were (1) to follow the time course of the development of polydipsia over days, and (2) to observe the interaction of water drinking and bar pressing, where neither was related to the delivery of reinforcements. Method Experiment 1. Two naive, adult, male, albino rats, A-2 and A-3, were maintained at 80% of ad lib weight, and received daily experimental sessions in a sound-insulated, ventilated, lighted chamber containing a lever in one wall, a food cup in a second wall, and a water-bottle nozzle in a third wall. Sessions consisted of the delivery of 100 45-mg Noyes pellets, one every 60 sec. (an F60 schedule). Licks at the water nozzle were recorded, but neither licks nor bar presses affected the delivery of pellets. The experiment lasted 30 days.E xp e rim e n t 2. Two additional naive, adult, male, albino rats, 0 and C-A, were subjected to an F60schedule, but this time the lever, food cup and waterbottle nozzle were on the same wall of the chamber, with the lever in the middle. Operant-level lever presses, as well as licks. were recorded. After the eleventh session, a 5-sec. delay of reinforcement was imposed, so that a pellet was never delivered sooner than 5 sec. following a bar press. The experiment lasted 16 days. Results and Discussion Ex per i men t 1. The upper portion of Fig. 1 shows the first 10-pellet deliveries from sessions 2, 3, 6, 13 and 14 (no graphic records were taken on session 1). The pattern of drinking was relatively stable from session 14 on. The upper tracing in each day's record shows cumulative water licks between food pellets; diagonal deflections indicate 2-sec. intervals during drinking bursts. The lower traCing shows the delivery of food. Both rats drank more frequently, and for longer durations, as the experiment went on. A2 drank after 16% of the pellets on session 2, 65% on session 6, 86% on session 13, and 95% on session 14. Thereafter the percentages fluctuated between 74% and 96%. A3 drank after 24% of the pellets on day 2, 75% on day 6, 85% on day 13, and 94% on day 14. Thereafter the percentages fluctuated between 55% and 89%. The modal duration of ...

Excessive drinking in rats’ adaptation to the schedule of feeding

“…Schedule induced polydipsia, originally described by Falk (1961aFalk ( , 1961b has been interpreted as due to adventitious reinforcement (Clark, 1962;Segal, 1965). stein (1964) found little supporting evidence for an adventitious reinforcement explanation and as an alternative suggested that rats have a tendency to drink after eating dry food.…”

Adjunctive drinking during variable and random-interval food reinforcement schedules

“…Although the possibility cannot be ruled out that with more sessions eventually even these RI rats might have developed interim drinking, the lack of any systematie upward trends in either their drinking or licking makes this seem unlikely. EIsewhere it has been shown that schedule-induced drinking under VI 60-lSec and similar schedules generally is asymptotie by 10 to 15 sessions (e.g., King & Schaeffer, 1973;Sanger & Blackman, 1975;Segal, 1965).…”

Concurrent drinking by pigeons on fixed-interval reinforcement schedules

“…In particular, none of the pigeons in the present experiment, with the exception of S3 on the FI 50-sec schedule, increased their mean bout frequencies or durations across sessions within an experimental condition. Rats exposed to intermittent food presentations avidly increase both the frequencies and durations of their drinking bouts [20], although the mean water intake per bout eventually stabilizes and appears to be orally monitored and regulated [9,12]. The finding that polydipsia is reliably induced in rats, but not in pigeons, exposed to FI food reinforcement schedules seems to depend on the fact that rats, but not pigeons, increase their drinking frequencies and tend to drink after virtually every food presentation.…”