Outcome expectancy and suboptimal risky choice in nonhuman primates

Area of Science:

• Behavioral neuroscience
• Primate cognition
• Decision-making under uncertainty

Background:

• Animals often exhibit "gambling-like" behavior, favoring risky choices when reward cues are present.
• Understanding the cognitive mechanisms behind these choices, particularly outcome expectancy, is crucial.

Purpose of the Study:

• To investigate signal-induced risky choices and reward-outcome expectations in rhesus and capuchin monkeys.
• To determine if delay-truncation responses reflect strategic decision-making or conditioned responses.

Main Methods:

• Assessed risky choice by comparing preference for large-probabilistic vs. modest-certain rewards.
• Measured outcome expectancy using a delay-truncation response to shorten reward delays.
• Included perceptual judgment tasks to probe metacognitive processes in capuchin monkeys.

Main Results:

• Both species favored signaled risky options over safe ones, except when a loss was signaled.
• Monkeys selectively truncated delays when rewards were anticipated, even with metacognitive awareness.
• Delay truncation was reduced when rewards were not expected (e.g., risky-loss trials).

Conclusions:

• Signaled outcomes promote risky choices, akin to gambling behavior in primates.
• Delay truncation responses reflect explicit outcome expectancy and strategic decision-making, not just conditioned responses.
• Primate decision-making involves sensitivity to reward cues and potential metacognitive awareness.