- Email: [email protected]
Infant perception of reaction at a distance
726
INFANT PERCEPTION
OF REACTION AT A DISTANCE.
Anne Schlottmann & Luca Surian Psychology Department University College London, Gower Street, London, WC1 6BT UK This study investigates infants’ sensitivity to causation at a distance. Previous research has shown that infants are sensitive to contact causality in collision events (e.g., Leslie & Keeble, 1987). We use an analogous approach to study whether infants can also perceive causality in visual motion sequences that do not involve physical contact between objects. Thirty-two 9-month-olds were randomly assigned to the ‘reaction’ or ‘pause’ group. Both groups were habituated to superficially similar computer-generated events involving two rectangular shapes moving across the screen in a nonrigid manner (a rhythmic elongation similar to that observed in caterpillars, see Michotte, 1963. Adults reported an impression of animal-like movement). Initially, red was stationary on the left, green in the middle (direction was counterbalanced). Red then started moving towards green, stopping slightly before reaching green’s initial position. Green moved in turn, but in the ‘reaction’ event it started before red had stopped. In the ‘pause’ event, however, green only started one second after red had stopped. Adults judged green’s movement to be a dire& reaction to red’s movement in the reaction but not the pause event. They made the same distinction for collisions with and without pause. In the reaction event, however, adults went on to judge that green moved to avoid capture, whereas in the collision event it moved because it had been hit. Adults thus distinguish between physical and ‘intentional’ causality depending - among other factors on contact. Infants, on reaching habituation criterion (< 50% of looking time on first 3 trials), saw a familiar and a reversal test event. If during habituation and familiar test red had moved from the left towards green, on reversal green moved from the right towards red. Reversal involved identical changes in spatiotemporal parameters for both groups. However, in the reaction, but not the pause event, reversal also involved a change in causal roles (i.e. the ‘hunter’ became the ‘hunted’). If infants are sensitive to the causal structure of this event, dishabituation on reversal should be enhanced relative to the pause group. The results provided modest but meaningful support for this prediction. In the pause group, there was no recovery of looking from familiar (I 1.4 sets) to reversal test event ( 10.6 sets). In the reaction group, however, babies looked longer at the reversal (12.5 sets) than the familiar event (9.5 sets). The Group x Test Event interaction reached F( 1,28) = 4.09, p =.053. No other difference between groups during habituation or test came close to significance. These results have implications for theories of conceptual development. It is animate agents which can affect each other at a distance due to their ability to perceive distal stimuli, and this is one way to distinguish them from inanimate objects. A perceptual mechanism to identify and parse some cases of reaction at a distance might facilitate learning about agency and causality between agents, just as a perceptual mechanism to identify some instances of mechanical causality can facilitate learning about causality between inanimate objects (see Leslie, 1988). Acknowledgements: We thank the MRC Cognitive Development Unit where this study was conducted. It was supported by a grant from the Nuffield Foundation. References: Leslie, A. M. (1988). The necessity of illusion: Perception and thought in infancy. In L.Weiskrantz (Ed),Thought without language, (p.185-210). Oxford: Oxford University Press. Leslie, A. M., & Keeble, S. (1987). Do six-month-old infants perceive causality? Cognition, 25, 265-288. Michotte, A. E. (1963). The perception of causality. (Tr. by T. R. Miles & E. Miles.) London: Methuen. Original published 1946.
INFANT PERCEPTION
OF REACTION AT A DISTANCE.
Anne Schlottmann & Luca Surian Psychology Department University College London, Gower Street, London, WC1 6BT UK This study investigates infants’ sensitivity to causation at a distance. Previous research has shown that infants are sensitive to contact causality in collision events (e.g., Leslie & Keeble, 1987). We use an analogous approach to study whether infants can also perceive causality in visual motion sequences that do not involve physical contact between objects. Thirty-two 9-month-olds were randomly assigned to the ‘reaction’ or ‘pause’ group. Both groups were habituated to superficially similar computer-generated events involving two rectangular shapes moving across the screen in a nonrigid manner (a rhythmic elongation similar to that observed in caterpillars, see Michotte, 1963. Adults reported an impression of animal-like movement). Initially, red was stationary on the left, green in the middle (direction was counterbalanced). Red then started moving towards green, stopping slightly before reaching green’s initial position. Green moved in turn, but in the ‘reaction’ event it started before red had stopped. In the ‘pause’ event, however, green only started one second after red had stopped. Adults judged green’s movement to be a dire& reaction to red’s movement in the reaction but not the pause event. They made the same distinction for collisions with and without pause. In the reaction event, however, adults went on to judge that green moved to avoid capture, whereas in the collision event it moved because it had been hit. Adults thus distinguish between physical and ‘intentional’ causality depending - among other factors on contact. Infants, on reaching habituation criterion (< 50% of looking time on first 3 trials), saw a familiar and a reversal test event. If during habituation and familiar test red had moved from the left towards green, on reversal green moved from the right towards red. Reversal involved identical changes in spatiotemporal parameters for both groups. However, in the reaction, but not the pause event, reversal also involved a change in causal roles (i.e. the ‘hunter’ became the ‘hunted’). If infants are sensitive to the causal structure of this event, dishabituation on reversal should be enhanced relative to the pause group. The results provided modest but meaningful support for this prediction. In the pause group, there was no recovery of looking from familiar (I 1.4 sets) to reversal test event ( 10.6 sets). In the reaction group, however, babies looked longer at the reversal (12.5 sets) than the familiar event (9.5 sets). The Group x Test Event interaction reached F( 1,28) = 4.09, p =.053. No other difference between groups during habituation or test came close to significance. These results have implications for theories of conceptual development. It is animate agents which can affect each other at a distance due to their ability to perceive distal stimuli, and this is one way to distinguish them from inanimate objects. A perceptual mechanism to identify and parse some cases of reaction at a distance might facilitate learning about agency and causality between agents, just as a perceptual mechanism to identify some instances of mechanical causality can facilitate learning about causality between inanimate objects (see Leslie, 1988). Acknowledgements: We thank the MRC Cognitive Development Unit where this study was conducted. It was supported by a grant from the Nuffield Foundation. References: Leslie, A. M. (1988). The necessity of illusion: Perception and thought in infancy. In L.Weiskrantz (Ed),Thought without language, (p.185-210). Oxford: Oxford University Press. Leslie, A. M., & Keeble, S. (1987). Do six-month-old infants perceive causality? Cognition, 25, 265-288. Michotte, A. E. (1963). The perception of causality. (Tr. by T. R. Miles & E. Miles.) London: Methuen. Original published 1946.