Abstract
This paper describes two experiments on the temporal differences in expressions for the following three types of laughter: “Spontaneous Laughter” caused by funny video clips, “Forced Laughter” evoked during uninteresting comedy clips, and “Extreme Forced Laughter” evoked only by instructions. In the first measurement experiment, facial muscle activity from the orbicularis oculi and zygomatic muscle region, and respiratory changes, were recorded for 15 male and 17 female subjects. The start times of their reactions were analyzed. The subjects took the Yatabe-Guilford personality test, and were classified into two groups: sociable or unsociable. The results showed significantly different time lags between eye and respiratory changes among the three types of laughter. They also showed significantly different time lags between eye and mouth responses in the sociable-male and unsociable-female groups. In the second observation experiment, 12 male and 13 female observers watched the first experiment's subjects' behaviors which were videotaped. They were asked to rate the naturalness of the laughter expressions. The observers' ratings were not very accurate. The ratings were significantly different in the gender of the subjects and the observers.
