Monkeys are more patient in a foraging task than in a standard intertemporal choice task

Area of Science:

• Behavioral economics
• Animal cognition
• Comparative psychology

Background:

• Animal impulsivity is often measured by steep discounting of delayed rewards.
• Steep discounting contradicts evolutionary models of time preference.
• Discounting tasks may not accurately reflect animals' true time preferences.

Purpose of the Study:

• To test if discounting tasks accurately measure animal time preferences.
• To investigate the external validity of intertemporal choice tasks in animals.
• To compare animal patience in foraging versus choice tasks.

Main Methods:

• Four rhesus monkeys completed interleaved intertemporal choice and patch-leaving foraging tasks.
• Choices in both tasks were analyzed to estimate time preferences.
• Behavior in the foraging task was modeled using optimal foraging equations.

Main Results:

• Monkeys exhibited significantly greater patience in the foraging task compared to the intertemporal choice task.
• Foraging behavior aligned with optimal foraging models, not discounting parameters.
• Time preferences across tasks were uncorrelated, indicating a lack of external validity.

Conclusions:

• Seemingly impulsive animal behavior may stem from task comprehension difficulties.
• Intertemporal choice tasks may overestimate animal impatience.
• Animals might be more efficient rate maximizers than standard tasks suggest.