Masako Hirotani

People's behaviors synchronize. It is difficult, however, to determine whether synchronized behaviors occur in a mutual direction-two individuals influencing one another-or in one direction-one individual leading the other, and what the underlying mechanism for synchronization is. To answer these questions, we hypothesized a non-leader-follower postural sway synchronization, caused by a reciprocal visuo-postural feedback system operating on pairs of individuals, and tested that hypothesis both experimentally and via simulation. In the behavioral experiment, 22 participant pairs stood face to face either 20 or 70 cm away from each other wearing glasses with or without vision blocking lenses. The existence and direction of visual information exchanged between pairs of participants were systematically manipulated. The time series data for the postural sway of these pairs were recorded and analyzed with cross correlation and causality. Results of cross correlation showed that postur...

This study investigated the role of joint attention in infants' word learning. Infants aged 18-21 months were taught new words in two social contexts, joint attention (eye contact, positive tone of voice) or non-joint attention (no eye contact, neutral tone of voice). Event-related potentials were measured as the infants saw objects either congruent or incongruent with the taught words. For both social contexts, an early negativity was observed for the congruent condition, reflecting a phonological-lexical priming effect between objects and the taught words. In addition, for the joint attention, the incongruent condition elicited a late, widely distributed negativity, attributed to semantic integration difficulties. Thus, social cues have an impact on how words are learned and represented in a child's mental lexicon.

During dialogue, there is a strong tendency for interlocutors to” align” on particular patterns of behaviour, for example using the same names for objects (eg, Brennan & Clark, 1996). Such lexical alignment enhances communication and reduces cognitive effort. Lexical alignment is not however uniform: speakers are less likely to align with a term if it is highly dispreferred and/or they have previously used an alternative term themselves (eg, Pearson et al, 2004). However, speakers can be induced to align in these circumstances if they ...

... The viewing distance was 1 m and one character subtended 0.5° of visual angle. ... a black background in monospaced Osaka font, such that all characters were the same size. ... calibration accuracy was checked prior to every item, and recalibrations were undertaken if necessary. ...