Schedule-induced drinking in humans: a potential factor in excessive alcohol use

Area of Science:

• Behavioral psychology
• Human-animal comparative psychology

Background:

• Schedule-induced drinking is a phenomenon where fluid intake increases during periods of intermittent reinforcement.
• Previous research in animal models suggests reinforcement schedules influence adjunctive behaviors.

Purpose of the Study:

• To investigate the effect of timed monetary reinforcement on fluid consumption in humans.
• To compare the influence of different Fixed-Interval (FI) schedules on adjunctive drinking behavior.

Main Methods:

• Human subjects were exposed to a computer-controlled slot machine delivering monetary reinforcement.
• Reinforcement was delivered on either a 30-second (FI30 s) or 90-second (FI90 s) Fixed-Interval schedule.
• Subjects had access to water, non-alcoholic beer, or alcoholic beer during the experimental sessions.

Main Results:

• Monetary reinforcement significantly altered fluid intake, demonstrating schedule-induced drinking in humans.
• Greater fluid consumption was observed under the FI90 s schedule compared to the FI30 s schedule across all fluid types.
• The largest difference in intake between schedules was noted when water was the available fluid.

Conclusions:

• Timed monetary reinforcement can induce fluid consumption in humans, mirroring findings in animal studies.
• Reinforcement schedule density influences the magnitude of schedule-induced drinking.
• Further research is needed to explore interactions with factors affecting human alcohol consumption.