The research was designed to evaluate interpersonal coordination during conversation with a new measurement tool. The experiment uses an analysis based on recurrence strategies, known as cross recurrence quantification, to evaluate the shared activity between 2 postural time series in reconstructed phase space. Pairs of participants were found to share more locations in phase space (greater recurrence) in conditions where they were conversing with one another to solve a puzzle task than in conditions in which they convened with others. The trajectories of pairs of participants also showed less divergence when they conversed with each other than when they conversed with others well. This is offered as objective evidence of interpersonal coordination of postural sway in the context of a cooperative verbal task.

People coordinate body postures and gaze patterns during conversation. We review literature showing that (1) action embodies cognition, (2) postural coordination emerges spontaneously when two people converse, (3) gaze patterns influence postural coordination, (4) gaze coordination is a function of common ground knowledge and visual information that conversants believe they share, and (5) gaze coordination is causally related to mutual understanding. We then consider how coordination, generally, can be understood as temporarily coupled neuromuscular components that function as a collective unit known as a coordinative structure in the motor control literature. We speculate that the coordination of gaze and body sway found in conversation may be understood as a crossperson coordinative structure that embodies the goals of the joint action system.

Imitation of shadowed words was evaluated using Goldinger's (1998) AXB paradigm. The first experiment was a replication of Goldinger's experiments with different tokens. Experiment 1's AXB tests showed that shadowed words were judged to be better imitations of target words than were baseline (read) counterparts more often than chance (.50). Order of presentation of baseline and shadowed words in the AXB test also significantly influenced judgments. Degree of prior exposure to token words did not significantly influence judgments of imitation. Experiment 2 employed modified target tokens with extended voice onset times (VOTs). In addition to AXB tests, VOTs of response tokens were compared across baseline and shadowing conditions. The AXB tests revealed shadowed words to be better imitations of target tokens than baseline, without an influence of AXB presentation order. Differences between baseline and shadowing VOTs were greater when VOTs were extended. The implications of spontaneous imitation in nonsocial settings are considered.