Fearful snake pictures make monkeys pessimistic

Area of Science:

• Animal behavior
• Cognitive ethology
• Affective neuroscience

Background:

• Judgment bias describes how an animal's emotional state influences its expectations of ambiguous situations.
• Understanding judgment biases from ecologically relevant stimuli is crucial for assessing their adaptive significance.
• Previous research has not sufficiently explored how predator-related cues impact judgment biases in animals.

Purpose of the Study:

• To investigate whether predator-related stimuli, specifically snake images, induce a pessimistic judgment bias in Japanese macaques (Macaca fuscata).
• To explore the adaptive role of such biases in environments with varying threat levels.

Main Methods:

• A touchscreen-based Go/No-go judgment bias test was employed with Japanese macaques.
• Subjects were exposed to predator-related stimuli (snake pictures) prior to ambiguous stimuli presentation.
• Response latencies and accuracy to ambiguous stimuli were recorded and analyzed.

Main Results:

• Japanese macaques exhibited a pessimistic judgment bias after viewing snake pictures.
• Subjects were slower and less likely to respond positively to ambiguous stimuli following exposure to snake images.
• This indicates a shift towards expecting negative outcomes when encountering threat cues.

Conclusions:

• Encountering predator-related stimuli, such as snakes, can induce a pessimistic judgment bias in Japanese macaques.
• This bias may be an adaptive mechanism to reduce risk-taking behavior in high-threat environments.
• Such affective responses to threat cues can curb excessive exploratory behavior, enhancing survival.