Fish can infer relations between colour cues in a non-social learning task

Area of Science:

• Cognitive ethology
• Animal behavior
• Comparative psychology

Background:

• Transitive inference (TI) is the ability to infer relationships between items not directly compared.
• Social animals, like cichlids, use TI in social dominance hierarchies.
• Domain-general cognitive mechanisms are proposed to function across different contexts.

Purpose of the Study:

• To investigate if the cooperatively breeding cichlid, *Neolamprologus pulcher*, can perform transitive inference in a non-social context.
• To determine if TI abilities, typically observed in social settings, generalize to artificial stimuli and non-social tasks in fish.
• To explore the domain-generality of cognitive processes in fish.

Main Methods:

• An associative learning paradigm was employed using a color discrimination task with food rewards.
• Fish were trained to associate colors with outcomes.
• Performance on inferring relationships between novel color pairs was assessed.

Main Results:

• Eleven out of 12 fish subjects correctly chose the predicted outcome for transitive inference in the initial test trial.
• Five subjects achieved 100% accuracy over six successive test trials.
• No evidence of value transfer was found as the mechanism for solving the task.

Conclusions:

• *Neolamprologus pulcher* can successfully apply transitive inference to non-social tasks involving artificial stimuli.
• These findings extend previous research on TI in social contexts to a non-social domain in fish.
• The results support the hypothesis that transitive inference may be a domain-general cognitive mechanism in fish.