Emerging perception of causality in action-and-reaction sequences from 4 to 6 months of age

Two experiments (N=136) studied how 4- to 6-month-olds perceive a simple schematic event, seen as goal-directed action-and-reaction from age 3. In our causal reaction event, a red square moved towards a blue square, stopping prior to contact; blue began to move away before red stopped, so that both briefly moved simultaneously at a distance. Primarily, our study sought to determine from what age infants see the causal structure of this reaction event. In addition, we looked at whether this causal percept depends on an animate style of motion, and whether it correlates with tasks assessing goal perception and goal-directed action. Infants saw either causal reactions, or non-causal delayed control events, in which blue started some time after red stopped. Events involved squares that either moved rigidly or non-rigidly, in apparently animate manner. After habituation to one of the four events, infants were tested on reversal of the habituation event. Spatio-temporal features reversed for all events, but causal roles changed only in reversed reactions. Six–month-olds dishabituated significantly more to reversal of causal reaction than non-causal delay events, younger infants reacted similarly to reversal of both. Thus perceptual causality for reaction events emerges by 6 months, a younger age than previously reported, but, crucially, the same age at which perceptual causality for launch events has emerged in prior research. On our second question, animate/inanimate motion had no effect at any age, nor did significant correlations emerge with our additional tasks assessing goal perception or goal-directed object retrieval. Available evidence, here and elsewhere, is as compatible with a view that infants initially see A affecting B, without differentiation into physical or psychological causality, as with the standard assumption of distinct physical/psychological causal perception.