Pigeons' (Columba livia) intertemporal choice in binary-choice and patch-leaving contexts

Area of Science:

• Behavioral Economics
• Animal Cognition
• Neuroscience

Background:

• Self-control is often studied via simultaneous choices between smaller-sooner (SS) and larger-later (LL) rewards.
• Patch-leaving tasks offer an alternative paradigm where staying or leaving determines reward acquisition.
• Previous research indicates species differences in reward preference between these task types.

Purpose of the Study:

• To systematically replicate and investigate intertemporal choice behavior in pigeons using both binary-choice and patch-leaving tasks.
• To examine the influence of reward magnitude, delay, and task structure on choice behavior.
• To explore the underlying mechanisms, potentially involving conditioned reinforcement and win-stay biases.

Main Methods:

• Six pigeons were tested in a binary-choice task and two patch-leaving tasks (Patch-L and Patch-S).
• Reward delays were manipulated, with smaller-sooner (SS) delays ranging from 5 to 55 seconds and larger-later (LL) delays fixed at 60 seconds.
• Variations included increased effort for staying and equal reward delays.

Main Results:

• Pigeons consistently preferred the SS reinforcer in binary-choice conditions.
• In patch-leaving tasks, pigeons preferred the LL reinforcer in Patch-L and the SS reinforcer in Patch-S, demonstrating a bias to stay.
• This stay bias persisted even with increased effort or equal reward delays.

Conclusions:

• Pigeons exhibit a stay bias in patch-leaving tasks, preferring to remain in a situation even when an immediate smaller reward is available.
• This behavior may be explained by a win-stay bias and conditioned reinforcement, where the patch stimulus becomes associated with reward.
• The findings challenge the economic equivalence of binary-choice and patch-leaving procedures and highlight context-dependent intertemporal choice mechanisms.