Perception of Individual and Joint Action in Infants and Adults

Abstract

Infants and adults frequently observe actions performed jointly by more than one person. Research in action perception, however, has focused largely on actions performed by an individual person. Here, we explore how 9- and 12-month-old infants and adults perceive a block-stacking action performed by either one agent (individual condition) or two agents (joint condition). We used eye tracking to measure the latency of participants’ gaze shifts towards action goals. Adults anticipated goals in both conditions significantly faster than infants, and their gaze latencies did not differ between conditions. By contrast, infants showed faster anticipation of goals in the individual condition than in the joint condition. This difference was more pronounced in 9-month-olds. Further analyses of fixations examined the role of visual attention in action perception. These findings are cautiously interpreted in terms of low-level processing in infants and higher-level processing in adults. More precisely, our results suggest that adults are able to infer the overarching joint goal of two agents, whereas infants are not yet able to do so and might rely primarily on visual cues to infer the respective sub-goals. In conclusion, our findings indicate that the perception of joint action in infants develops differentially from that of individual action.

The use of intonation for turn anticipation in observed conversations without visual signals as source of information

“…Positive values indicate an anticipatory gaze shift; negative values indicate a reactive gaze shift. Second, we analyzed the location and duration of fixations provided by the data acquisition software ( fixation duration ; Keitel et al, 2014 ). Fixation duration can indicate distraction.…”

“…Gaze shifts towards a speaker were only regarded valid if they were immediately preceded by a 100-ms fixation on the other speaker. This limitation was included to ensure that a gaze shift was related to the conversation and not random ( Keitel et al, 2013 , 2014 , see also Melzer et al, 2012 ).…”

Finding events in a continuous world: A developmental account

“…Beyond the ability to predict goals, there are developmental improvements in the breadth of actions that infants can successfully predict. Keitel, Prinz, and Daum () demonstrated that while adults’ predictions of manual action goals in a block stacking event are comparable whether one actor is stacking blocks or two actors are taking turns stacking the blocks, infants’ predictions are slower for the goals of joint, coordinated action relative to individual action, and this asymmetry is more robust for 9‐month‐olds than 12‐month‐olds. Infants’ ability to predict the goal of one agent's actions may precede their ability to predict the overarching goal of two agents’ actions (i.e., also referred to as super‐ordinate action prediction ; Uithol & Paulus, ) because most of the infants’ actions until this point have been directed toward individual goals rather than higher‐level joint goals coordinated with others.…”

Not Just Being Lifted: Infants are Sensitive to Delay During a Pick-Up Routine

“…They presented evidence of early cooperative understanding during early communicative interactions between young infants and their mothers, by showing that from 8 to 12 month infants increased their ability to integrate expressions of interpersonal communication with cooperative praxic acts ( Hubley and Trevarthen, 1979 ). On the other hand, Keitel et al (2014) cautiously proposed that infant perception of joint actions develops starting at 9 month and differs from their perception of individual actions; in other words, before 9 month they are not expected to cooperate.…”