Action mirroring in 9-month-olds: Let’s take turns!

• In Event: 2-128 - Function and Development of the Mirror System in Infancy and Toddlerhood

Integrative Statement

Action and perception of others’ actions are closely linked in early childhood. The neural overlap of action production and perception (also called action mirroring) provides the neurocognitive basis for the processing of others’ actions. The precise functionality of the mirror mechanism, however, is matter of ongoing debate. Evidence from adult studies suggests that the mirror mechanism responds flexibly to different (social) situations rather than constituting an automatic process. Relatedly, findings with 3-year-old children show enhanced neural motor activity when they observe the actions of a joint action partner in a turn-taking game. Yet, how the interaction context in which infants observe others’ actions influences how they process others’ actions remains an open question. This is particularly surprising given the crucial role of processing others’ actions for social learning in the first year of life. In the current study, we address the question of whether infants show flexible, context-dependent action mirroring in their first year of life. More specifically, we examine whether turn-taking enhances action mirroring in infants.
We conducted an electroencephalography (EEG) study with 9-month-old infants in which we collected neural data while infants are grasping (execution) and observing an experimenter grasp toys (observation). To examine whether infants show flexible action mirroring, we manipulated the structure of the interaction (blocked vs. turn-taking). In the blocked structure, 10 consecutive trials of observation were followed by 10 execution trials. This was repeated, adding up to 20 trials per condition. In the turn-taking structure, each observation trial was followed by infants’ own execution (with a total of 20 trials per condition). We hypothesized that turn-taking would elicit stronger action mirroring than observing actions repeatedly before getting to act.
We have tested 66 9-month-olds (29 boys) in this live paradigm. The within-subjects conditions (observation; execution) were each preceded by a baseline (a person is visible but not acting). Experimental trials were time-locked to the moment of contact with the toy. EEG sessions were video-recorded and coded offline for infants’ movements. All baseline and observation segments contaminated by infants’ overt gross-motor movements were excluded from further analysis. To assess neural motor activity we analyzed power in infants’ alpha rhythm (6-9Hz). Suppression in this rhythm over sensorimotor areas (Mu-suppression) is an established index for neural motor activity in infants. Preliminary analyses of 24 participants with sufficient artifact- and movement-free data shows overall Mu suppression with respect to baseline during execution and observation, both p’s < .01 (see Figure 1). Furthermore, we found an interaction effect between Condition (Turn-Taking, Blocked) and Time (-1000ms to -500ms; -500ms to 0ms) indicating that infants engaged in turn-taking (N = 9) but not in the blocked context (N = 15) activated their motor system more strongly in the beginning as compared to the end of the reach-to-grasp period, F(1,22) = 7.6, p = .01. Analyses assessing details of the time-course and topographic specificity of the effect are forthcoming and their outcomes will be presented. Potential implications of engaging infants in turn-taking for their action understanding and social learning will be discussed.

Authors

• Marlene Meyer, University of Chicago
  Presenting Author

• Haerin Chung, University of Chicago
  Non-Presenting Author

• Amanda Woodward, University of Chicago
  Non-Presenting Author