Reinforcer control by comparison-stimulus color and location in a delayed matching-to-sample task

Area of Science:

• Behavioral Psychology
• Animal Cognition
• Learning and Memory

Background:

• Delayed matching-to-sample (DMTS) is a key paradigm for studying memory and choice behavior.
• Understanding how reinforcement history influences choice is crucial for behavioral models.

Purpose of the Study:

• To investigate how pigeons' choices in a DMTS task are affected by independent variations in reinforcement location and color.
• To compare the sensitivity of side-key and comparison-color biases to reinforcement distributions.

Main Methods:

• Six pigeons were trained on a DMTS task with yellow sample stimuli and red/green comparison stimuli.
• Reinforcer delivery was systematically varied across key location and color independently.
• Response ratios (left/right and red/green) were analyzed in relation to reinforcer ratios.

Main Results:

• Matching accuracy remained high across conditions.
• Side-key responses tracked the ratio of left to right reinforcers.
• Comparison-color responses tracked the ratio of red to green reinforcers, with no interaction.
• Side-key biases showed greater sensitivity to location-based reinforcement than color biases did to color-based reinforcement.

Conclusions:

• Pigeon's choice behavior in DMTS is differentially controlled by reinforcement location and color.
• Findings support an extended Davison and Tustin (1978) model but are also consistent with alternative conditional discrimination theories.
• The results highlight the importance of considering independent reinforcement dimensions in understanding choice behavior.