Identifying living and sentient kinds from dynamic information: the case of goal-directed versus aimless autonomous movement in conceptual change.

To reason competently about novel entities, people must discover whether the entity is alive and/or sentient. Exactly how people make this discovery is unknown, although past researchers have proposed that young children--unlike adults--rely chiefly on whether the object can move itself. This study examined the effect of goal-directed versus aimless autonomous movement on children's and adults' attributions of biological and psychological capacities in an effort to test whether goal-directedness affects inferences across documented periods of change in biological reasoning. Half of the participants (adults, and 4-, 5-, 7-, and 10-year-olds; Ns=32) were shown videos of unfamiliar blobs moving independently and aimlessly, and the other half were shown videos of identical blobs moving identically but toward a goal. No age group was likely to attribute biological or psychological capacities to the aimless self-moving blobs. However, for 5-year-olds through adults, goal-directed movement reliably elicited life judgments, and it elicited more biological and psychological attributions overall. Adults differed from children in that goal-directed movement affected their attributions of biological properties more than their attributions of psychological properties. The results suggest that both young children and adults consider the capacity for goal-directed movement to be a decisive factor in determining whether something unfamiliar is alive, though other factors may be important in deciding whether the thing is sentient.