Work

Gibbons (Nomascus leucogenys), siamangs (Symphalangus syndactylus), and chimpanzees (Pan troglodytes) account for proportional probabilities in a two-choice task.

Year: 2025

Type: article

Abstract: ) with a proportional probability task requiring them to reason from the distribution of items in a population to the likely contents of a sample. In contrast to previous research, we ensured that participants could not rely on two salient heuristics-the absolute quantity of the preferred item or majority sampling-to solve the task. We found that individuals of all species were able to distinguish between 0% versus 50% and 50% versus 100%, and that two individuals (one chimpanzee and one siamang) were able to convincingly distinguish between 33% versus 67%. These results suggest that an antecedent to probabilistic reasoning was shared by a common ancestor of humans, great apes, and small apes. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Source: Journal of comparative psychology

DOI: 10.1037/com0000437

Authors: Jessica Crimston, Sue Tonga, Jonathan Redshaw, Thomas Suddendorf

Institution: The University of Queensland

Language: English

Topic: Primate Behavior and Ecology

Subfield: Social Psychology

Field: Psychology

Domain: Social Sciences

Open Access status: hybrid

Funder: Australian Research Council

Award: Gaining control of the future: The cognitive development of foresight