Choice of timeout from fixed-time schedules: Comparison of two procedures

Area of Science:

• Behavioral neuroscience
• Animal behavior

Background:

• Fixed-time (FT) schedules deliver reinforcement after a set interval.
• Lever pressing during FT schedules can initiate timeout periods where reinforcement is unavailable.

Purpose of the Study:

• To investigate how timeout periods are affected by FT schedule length and timing conditions.
• To examine the relationship between timeout initiation and reinforcement schedules.

Main Methods:

• Four rats were exposed to FT schedules (1, 4, 16 min) with varying timeout conditions.
• Two conditions were tested: 'Stop' (FT interval paused during timeout) and 'No Stop' (FT interval continued).
• Data collected included percentage of session time in timeout, rate of timeout initiation, and mean timeout duration.

Main Results:

• Timeout percentage increased with longer interfood intervals, irrespective of the 'Stop' or 'No Stop' condition.
• The 'Stop' condition resulted in a larger timeout percentage with longer interfood intervals.
• Timeout initiation rate increased from FT 1-min to FT 4-min, then plateaued or decreased at FT 16-min.

Conclusions:

• Timeout percentage is determined by interactions between timeout rate, duration, and interfood interval.
• Findings suggest timeout initiation is a facultative behavior, not an escape from aversive reinforcement.
• Behavioral control in FT schedules involves complex interactions between timing and reinforcement delivery.