Keeping the end in mind: Preliminary brain and behavioral evidence for broad attention to endpoints in pre-linguistic infants.

Infants must learn to carve events at their joints to best understand who is doing what to whom or whether an object or agent has reached its intended goal. Recent behavioral research demonstrates that infants do not see the world as a movie devoid of meaning, but rather as a series of sub-events that include agents moving in different manners along paths from sources to goals. This research uses behavioral and electrophysiological methods to investigate infants' (10-14 months) attention to disruptions within relatively unfamiliar human action that does not rely on goal-objects to signal attainment (i.e., Olympic figure skating). Infants' visual (Study 1, N = 48) and neurophysiological (Study 2, N = 21) responses to pauses at starting points, endpoints, and within-action locations were recorded. Both measures revealed differential responses to pauses at endpoints relative to pauses elsewhere in the action (i.e., starting point; within-action). Eye-tracking data indicated that infants' visual attention was greater for events containing pauses at endpoints relative to events with pauses at starting points or within-actions. ERP activity reflecting perceptual processes in early-latency windows (<200 ms) and memory updating processes in long-latency windows (700-1000 ms) showed differential activation to disruptions at the end of a figure-skating action compared to other locations. Mid-latency windows (250-750 ms), in contrast, showed enhanced activation at frontal regions across conditions, suggesting electrophysiological resources may have been recruited to encode disruptions within unfamiliar dynamic human action. Combined, results hint at broad sensitivity to endpoints as a mechanism that supports infants' proclivity for carving continuous and complex event streams into meaningful units. Findings have potential implications for language development as these units are mapped onto budding linguistic representations. We discuss empirical and methodological contributions for action perception and address potential merits and pitfalls of applying behavioral techniques in conjunction with brain-based measures to study infant development.