Sensitivity to reinforcement in successive and delayed discriminations

Area of Science:

• Behavioral psychology
• Animal cognition

Background:

• Pigeons demonstrate complex learning behaviors under various reinforcement schedules.
• Understanding stimulus control is crucial in operant conditioning research.

Purpose of the Study:

• To investigate how pigeons' response rates are affected by reinforcement schedules in the presence and absence of discriminative stimuli.
• To compare the effects of standard multiple schedules versus delayed discrimination (memory) procedures on pigeon behavior.

Main Methods:

• Pigeons were exposed to multiple variable-interval schedules of food reinforcement.
• Response patterns were analyzed across successive 15-second subintervals within 60-second components.
• Two procedures were used: standard multiple schedule (stimuli present throughout) and delayed discrimination (stimuli presented initially, followed by a neutral stimulus).

Main Results:

• Pigeon response rates in the initial 15 seconds were sensitive to reinforcement ratios in both procedures.
• Sensitivity to reinforcement decreased over time within components in both schedules.
• This decrease in sensitivity was more pronounced in the delayed discrimination procedure, indicating reduced stimulus control when discriminative stimuli were absent.

Conclusions:

• Delayed stimulus control by discriminative stimuli and time since reinforcement influence behavioral sensitivity.
• Pigeon behavior is sensitive to reinforcement history, even when discriminative cues are absent for part of the trial.