抄録
We humans have a tendency to mimic other's behavior unconsciously under social interactions, a phenomenon has been termed “chameleon effect” (Chartrand & Bargh, 1999). And recent studies are further investigating whether there is a tendency to modify not only category of movement but also timing of movement. In this presentation, we examined whether chimpanzees, highly social primate species, show a change in their own preferred tempo of a repetitive movement when they perceive the others' movement. We introduced a finger-tapping paradigm which is extensively used to in human studies to explore sensorimotor synchronization (Repp, 2005). Unlike the human studies that use piano key-board, we used touch screen monitor for the paradigm. Two visual targets appeared alternatively on two fixed locations of the touch screen monitor. When the target is pressed, it disappears and the other target appears. Therefore chimpanzees were able to sense that their tap was valid enough to continue the next tapping movement. Before the experiment starts, several months of training was needed in order to make chimpanzees tap the target more than 30 times. A data obtained during the training period shows that adults chimpanzees (four females, aged 28-35 years) have relatively slower tapping tempo than adolescent chimpanzees (one male, two females, aged 11 years). From the experiment, adult female and her child (11-year-old adolescent chimpanzee) became a pair and they sit side by side while conducting the task as they did in the training period. Because of the arrangement of those two monitors, visual information of the others' movement was occluded. Instead, auditory information of the movement was provided by feedback sound. The sound was played when the target was touched. We prepared 2 conditions in the experiment; base line and test condition. In the base line condition, chimpanzees conducted the task at different time. In contrast, in the test condition, a pair of chimpanzees conducted the task simultaneously. On the basis of obtained data, we will compute variance of relative phase and windowed cross correlation in order to see the effect of the others' tapping movement on the one's movement.
