Adaptation to 23.5-Hr. Food and Water Deprivation Schedules in the Rat and Guinea Pig

20 rats and 20 guinea pigs were compared on a 23.5-hr. water-deprivation schedule and on a 23.5-hr. food-deprivation schedule. Rats showed a satisfactory adjustment to both these schedules, while guinea pigs adjusted to water-deprivation but not to the food-deprivation schedule.

Bitter and Sweet Saccharin Preferences as a Function of Food Deprivation

16 rats were given 23-hr. tests with each of 2 low-concentration (sweet by human report) pairs of saccharin (.05% vs .15% and .05% vs .35%) and 2 high-concentration (bitter) pairs (1.15% vs 1.25% and 1.15% vs 1.45%). All Ss were tested under each condition while on ad lib. feeding and while on a 23-hr. food deprivation schedule. Results with the 2 low-concentration pairs showed the typical deprivation-concentration interaction, greatly increased intake for the higher concentration of a pair. There was also an interaction with the “bitter” pairs, due to Ss drinking more of the 1.15% concentration when food-deprived than when non-deprived.

Frontal Cortex Lesions and Fixed-Interval Acquisition in the Rat

This research was designed to study the behavioral effects of frontal cortex lesions upon the performance of rats in a fixed-interval reinforcement situation. Prior to testing, 10 Ss were prepared with posterior frontal cortical lesions in areas 10 and 6. 10 control Ss received sham operations. Following post-operative recovery, the animals were placed on a 23-hr. food deprivation schedule and trained to press a bar for a pellet of food which would be delivered only if 1 min. had elapsed since the previous reward. Analysis of variance showed no significant difference between the 2 groups in the ability to learn the temporal discrimination. However, lesioned Ss yielded a significantly divergent distribution of responses within the interval and a much lower terminal rate of response than the controls.

Drinking Behavior of Food-Deprived Rats during Feeding Sessions

As rats adapted to a food-deprivation schedule, they ate for progressively shorter periods before stopping to drink. The more severely Si were deprived of food, the less food they consumed before initiating drinking.

Is Hunger Drive Held Constant in the Behavior Experiment Employing a Fixed Food-Deprivation Schedule?

Body-weight curves based on 4 fixed-amount and 4 fixed-time maintenance schedules are reported. An examination of the literature, using those curves as criteria, suggests an unequivocal “no” to the question posed in the title of this paper. The same curves can serve as one basis for more knowledgably designed experiments in which fixed-deprivation schedules are deemed necessary or convenient.

Maintenance and Measurement of Water-Regulatory Variables through Controlled Feeding

Daily patterns of drinking were observed in rats under ad libitum feeding conditions and with a 22-hr. food deprivation schedule. It was found that feeding restricted to a specific hour set the daily drinking pattern and allowed a control of daily water-regulatory cycles. The amount of water ingested was found to be greater under the 22-hr. food deprivation than with ad libitum feeding.

Adjustment of the Rat to the 23-HR. Food-Deprivation Schedule under Two Conditions of Water Availability

Adjustment of rats to the 23-hr. food deprivation schedule was affected by presence or absence of water during the daily 1-hr. food-intake period. Ss with water adjusted in 15–20 days; Ss without water required an estimated 30–35 days to adjust.