title: New Caledonian crows reason about hidden causal agents.
abstract: The ability to make inferences about hidden causal mechanisms underpins scientific and religious thought. It also facilitates the understanding of social interactions and the production of sophisticated tool-using behaviors. However, although animals can reason about the outcomes of accidental interventions, only humans have been shown to make inferences about hidden causal mechanisms. Here, we show that tool-making New Caledonian crows react differently to an observable event when it is caused by a hidden causal agent. Eight crows watched two series of events in which a stick moved. In the first set of events, the crows observed a human enter a hide, a stick move, and the human then leave the hide. In the second, the stick moved without a human entering or exiting the hide. The crows inspected the hide and abandoned probing with a tool for food more often after the second, unexplained series of events. This difference shows that the crows can reason about a hidden causal agent. Comparative studies with the methodology outlined here could aid in elucidating the selective pressures that led to the evolution of this cognitive ability.
authors.affiliation: Department of Psychology, University of Auckland, Auckland 1142, New Zealand. alexander.taylor@auckland.ac.nz
authors.forename: Alex H
authors.initials: AH
authors.lastname: Taylor
authors.forename: Rachael
authors.initials: R
authors.lastname: Miller
authors.forename: Russell D
authors.initials: RD
authors.lastname: Gray
mesh_terms: D000818:Animals; D003071:Cognition / Q000502:physiology*; D046368:Crows / Q000502:physiology*; D009510:New Caledonia; D011340:Problem Solving / Q000502:physiology*; D053001:Tool Use Behavior / Q000502:physiology*