Analysis of Laugh
Abstract
The purpose of our research is to investigate the mechanism behind human communication.
Among various factors, laugh is said to be an emotional expression unique to mankind, and isan essential factor in facilitating smooth communication. We have focused on laugh, and areinvestigating the mechanism of laugh quantitatively.
Eﬀect of attention on classiﬁcation of smiles
In our previous work, we found that temporal diﬀerences of eye and mouth movements infacial expressions of smiles aﬀect the classiﬁcation of smiles [1]. While thinking this was because
subjects were paying attention to some speciﬁc part of the face, we carried out an experimentfor veriﬁcation purpose [2]. Several animations of smiling faces were created, each diﬀering
only in the starting time of eye motion and mouth motion. Prior to each animation, a location
marker was displayed for 0.7 sec. at either the position of the eyes or mouth. Then, after theanimation ended, a 5-digit random number was displayed for 0.3 sec. at the same position
as the marker. Subjects were asked to classify each smile, and to write down the displayed
number. As a result, we found that when subject’s attention was forced to the mouth, the ratio
to classify smiles as pleasant ones raised signiﬁcantly.
Analysis of forced laughter in time diﬀerences of facial and abdominal movements
There are two typical kinds of laughters; spontaneous laughter by something humorous andforced laughter to maintain a social relationship. We have clariﬁed properties for characterizingthese two types of laughter [3]. Laughter was analyzed when subjects (ﬁve males and tenfemales) were watching comical movies. Among various expressions of laughter, we analyzed
abdominal movements in addition to facial expressions (movements of the eyes and mouth).
Surface EMG (electromyography) signals of the eye and mouth movements, and abdominal
movements (using a strain gauge around each subject’s abdomen) were measured. As a result,
we found that abdominal reactions to forced laughter are later than those to spontaneouslaughter for males, but no signiﬁcant diﬀerence exists for females.
(Contact: Shuichi Nishio; Email: nishio@cslab.kecl.ntt.co.jp)[1] Nishio, S. and Koyama, K.: A Criterion for Facial Expression of Laugh Based on TemporalDiﬀerence of Eye and Mouth Movement (in Japanese), Trans. IEICE, Vol. J80-A, No. 8, pp.
1316–1318 (1997).
[2] Nishio, S., Koyama, K. and Nakamura, T.: Temporal Diﬀerences in Eye and Mouth Movements Classifying Facial Expressions of Smiles, Proc. Third IEEE International Conference
on Automatic Face and Gesture Recognition, pp. 206–211 (1998).
[3] Nakamura, T., Koyama, K., and Nishio, S.: Analysis of “Laughter of Claque” in time
diﬀerences of facial and abdominal movements (in Japanese), Proc. 5th Annual Conventionof Japan Society for Research on Emotions, p. 17 (1997).
0.19sec5-digit number

location marker

spontaneouslaughterface
abdomen
0.60sec

78534

0.7 sec.

animation of smiles

0.3 sec.

forcedlaughterface
abdomenFig. 1: An example of stimulus (eye condition) Fig. 2: Time diﬀerences of reactions in bothtypes of laughtercCopyright1998
Nippon Telegraph and Telephone Corporation