Speakers sometimes modify their gestures during the processof production into adaptors such as hair touching or eyescratching. Such disguised adaptors are evidence that thespeaker can monitor their gestures. In this study, weinvestigated when and how disguised adaptors are firstproduced by children. Sixty elementary school childrenparticipated in this study. There were ten from each schoolyear (from 7 to 12 years of age). They were instructed toremember a cartoon and retell its story to their parents. Theresults showed that children did not produce disguisedadaptors until the age of 8. The disguised adaptorsaccompany fluent speech until the children are 10 years oldand accompany dysfluent speech until they reach 11 or 12years of age. These results suggest that children start tomonitor their gestures when they are 9 or 10 years old.Cultural influences and cognitive changes were considered asfactors to influence emergence of disguised adaptors.

Raising hands is an important behavior in a classroom because children get a chance to participate in the class by doingit, and teachers use it to monitor how well children have understood the lesson. However, little is known about thehand raising behavior in a classroom. Thus, we examined to see if hand raising behavior varies with childrens age in anelementary school. Children in the first, third and fifth grades participated in this study. We recoded the teachers andchildrens behaviors and speech observed in Japanese language class and analyzed their interactions. The results showedthat fifth graders frequently raised their hands, while third graders raised them the least. The incidence of hand raisingduring anothers speech was also higher in fifth graders. This suggests that with age, children learn to use teacher and otherchildrens speech and non-verbal behavior as a resource to participate in a class.

Recently, cognitive science researchers have revealed that human cognition involves the body and is a kind of self- organization phenomenon emerging from dynamic interaction across body-brain-environment. Some of the data obtained from such cognitive, behavioral, or physiological activities are often complicated in terms of non-stationarity and nonlinearity. Researchers have proposed several analytical tools and frameworks. Recurrence analysis is one of the nonlinear data analyses developed in nonlinear dynamics. It has been applied to various research fields, including cognitive science, for language (categorical) data or motion (continuous) data. However, most previous studies have applied recurrence methods individually to categorical or continuous data. We aimed to integrate these methods to investigate the relationship between speech (categorical) and motion (continuous) directly. To do so, we added temporal information (a time stamp) to categorical data and applied the joint recurrence analysis methods to visualize and quantify speech-motion coordination during a rap performance. Our pilot study suggested the possibility of visualizing and quantifying it.

Mentalization is an important ability to acquire for children,as it allows humans to understand the mental state of others oroneself, that underlies overt behavior (Fonagy & Target,1996). In the current study we examined the relationshipbetween development of mentalization ability in children andtheir experience of playing with a doll by observing child-mother interaction and by using functional near-infraredspectroscopy (fNIRS). 44 dyads of children aged 2 to 3 andtheir mothers were divided into two groups (high and low)depending on the frequency of doll-play experience. Weexamined mother-speech interaction during the doll play. Wealso used fNIRS system to measure cerebral hemodynamicactivation in the frontal and temporal regions during theobservation of video clips showing hindering and helpingbehaviors. The results showed that a mother’s proxy talk wasrelated to a child’s doll directed speech in the high group, butnot in the low group. fNRIS data showed that cerebralactivation in the helping condition was more increased in thelow group than the high group. This suggests that doll-playexperience facilitates the development of mentalization,which enables children to be aware of and understand other'spsychological states.