Abstract
Acquiring triadic social interactions could facilitate language and communication skills in early infancy. However, studies have rarely investigated polynomial relationships, defined as relationships among the self, two or more people, and objects. During the development from a child to an adult, the responsiveness to a preferred stimulus modality changes from visual to auditory dominance. Nevertheless, how people observe compound visual stimuli in polynomial social relationships and why it is difficult to ignore auditory cues remain unclear. Moreover, there is a need to identify differences between children's and adults' observing latencies in the time to the first fixation when detecting a stimulus. This study examined whether participants (24 adults and 19 children) demonstrated similar gaze patterns under triadic and polyadic conditions. The participants observed a target visual stimulus looked at by a face stimulus while we presented spoken names, either congruent or incongruent with the target visual stimulus. The results indicated that when the number of people in social relationships increased, children and adults decreased fixations on the target face and the stimulus and showed a shorter mean fixation duration on the face. Moreover, children had longer latencies and more fixation errors for the target stimulus, which might reflect children's difficulties in communicating with others. We expect that understanding children's communication transition from triadic to polynomial social relationships with audio-visual stimulus congruencies would facilitate understanding language development and social communication patterns.