Visualization and quantification of human laughter

Visualization and quantification of human laughter

著者 Morita Ayako, Kimata Hajime journal or

publication title

人間健康学研究 : Journal for the study of health and well‑being

volume 5‑6

page range 77‑82

year 2013‑03‑31

URL http://hdl.handle.net/10112/00023266

Visualization and quantification of human laughter

Ayako Morita, Hajime Kimata

Abstract

The healthy effect of laughter has been supported by a lot of anecdotal reports and quantitative studies. However, the difficulty in measuring laughter with precision used to hinder detailed investiga- tion. Thus, improving the method of assessing laughter has now become a pressing issue. In this study, a new methodology using diaphragm electromyogram (EMG) to assess "sincere" laughter is recom- mended. This measuring system can contribute substantially to the development of many fields, including sociology, psychology, and medical science, because it does not require any special medical or mechanical technique. and method and utility are discussed in detail.

Key words: quantification of human laughter, diaphragm electromyogram, visualization of human laughter

Introduction

The beneficial effect of laughter on human health was originally reported by Norman Cousins, who had overcome ankylosing spondylitis with laughter!). Recently, various effects of laughter on human health have been reported: Laughter 1) augments the natural killer (NK) cell cytotoxicity in healthy subjects, 2) reduces inflammatory cytokines and alleviates pain in patients with rheumatoid arthritis, 3) reduces allergic responses and IgE production in patients with atopic dermatitis or allergic rhinitis, 4) increases breast milk leptin in healthy subjects and in patients with atopic dermatitis, 5) reduces bronchial responsiveness to allergens in patients with bronchial asthma, 6) inhibits the increase in postprandial blood glucose in patients with diabetes, and 7) improves brachia! artery flow in healthy subjests^2-7). In addition, laughter modulates the prorenin receptor gene expression or NK cell activity-related gene expression in patients with diabetes^{8· 9).}

In spite of a great deal of attractive reports, the process by which laughter affects health still is unclear.

Moreover, studies on laughter seem to have made little progress in 10 years, owing to some defects in the methods used. There are four methodological problems at the moment. First, the induction of laughter differs in each study. We laugh not only when watching comic videos, but also when observing the charming gestures of a child. Frequently, we also laugh for no particular reason - after eye contact with our friends during pleasant conversation or while watching comedy. Laughter induced by different factors in different situations should not be dealt with on the same level. Second, the style of laughter tends to be left out of consideration. It is not hard to conclude that hearty laughter and scornful laughter have different effects on health. Third, details about the quantity of laughter have been rarely mentioned. Thus, there is no reliable criterion to employ in determining whether a person laughs enough to improve his or her health.

Fourth, a method of assigning value to laughter has yet to be established. Common ways of estimating the amount of laughter are surface facial electromyograms, recorded laughter, questionnaires about how much funniness was felt, and monitoring how subjects laugh, but these measures do not seem to adequately assess laughter. The reason is that although these things normally accompany laughter, they are not laughter itself.

78  人間健康学研究 第5・6合併号

There is  growing demand for an accurate way of measuring laughter. It  would be best to use consistent  laughter to properly study its  effect.  Herbert Spencer, who proposed the Cognitive Incongruity theory,  suggested that laughter, having no object, is  the result of contractions of certain muscles by the uncontrolled  discharge of energy  . ¹⁰⁾ 

Here, we show that laughter was recorded by surface diaphragm EMG, which was then converted into  the  frequency  domain by the  fast  Fourier  transform.  This  method validates  the  visualization  and  quantification of laughter in both children and adults. 

Method 

After obtaining informed consent, 24 graduates and undergraduates of Kansai university (14 males and  10 females; age range: 21‑34 yrs) and 4 children (3 males and 1 female; age range: 1‑5 yrs) were recruited.  None of the subjects was under treatment for any disease or took medication at the time of study. 

The surface diaphragm EMGs of the adults were recorded while they were watching a funny video or  talking each other. The surface diaphragm EMGs of the children were recorded while they were playing 

"Peek‑a‑Boo," tickling each other, or playing the "outstaring" game. The signals were transformed into the  Fourier amplitude spectrum. 

Results 

The color spectrogram, which is a sort of sonograph, shows the results of frequency analysis (Figs. 1‑3).  The X‑axis indicates the出ne.Scale lines are drawn every 500 msec. The Y‑axis indicates frequency. Color  concentration represents the power of the frequency energy. The color changes from green to red in the  order of energy strength. 

We then tried to deterrrtlne the quantity of laughter by spectrum values. A diaphragm laughter wave has  4 or 5 block waves per second on the average. We specify the bandwidth and count the total amount of  laughter, taking the arithmetical mean of the spectrum value of the block wave as one unit. We named the  basic unit of laughter "aH." 

H + + + 1 ' + 1 + t t 1  

C(chlld)  D(adutt) 

- - ~

盲 ...  ~

Figure l.  Electrocardiograms of child and adult in  normal circumstances. 

Visualization and quantification of human laughter (Morita・Kimata)  79 

Figure2. Diaphragm laughter waves and laughter spectrogram of child and adult. 

Figure3. Spectrogram of laughter, crying, sneeze, and cough. 

Since an electrocardiogram (ECG) was mixed in with the EMC, we first assessed ECG of the children and  adults in normal circumstances. No bursting pattern was observed by EMC (Figs. lA and B) or color  spectrogram (Figs. lC and D). In contrast, the bursting pattern of EMC, which was composed of plural block  waves, was elicited by laughter, as shown in the diaphragm laughter wave (Figs. 2A and B). Though no  laughter wave was produced by any insincere smile or empty laughter, it  did appear when the subjects felt 

80

funniness, no matter how they tried to conceal their feelings and suppress their laughter.

As shown in Figs. 2C and D, the laughter spectrogram of the children was akin to those of the adults.

Although the diaphragm laughter wave of the children (Fig. 2A) showed only small and ambiguous ripples that were difficult to distinguish from noise, the waves' spectrum shape enabled us to verify that both children and adults were laughing. On the other hand, the spectrum shape of laughter obviously differed from that of crying, sneezing, and coughing (Figs. 3A-D).

Next was evaluating the quantity of laughter, represented as 41 aH in a child (Fig. 2A), 53 aH in one adult (Fig. 2B), and 23 aH in another adult (Fig. 3A). The quantity of laughter in child who was crying (Fig. 3B) was evaluated as O aH, because he did not laugh at all. For the same reason, the quantity of laughter in the adults who sneezed (Fig. 3C) and coughed (Fig. 3D) were O aH.

Discussion

Although the assessment of laughter has been reported by using various EMGs or sound spectrographs, the quantity of laughter has not been measured accurately¹1-14>. Moreover, most of them required special methods that needed special techniques and apparatus. Meanwhile, abdominal muscle EMGs were used to measure laughter in some studies even if abdominal muscles are not primarily involved in laughter. Thus, diaphragm EMG is more suitable in assessing laughter, although it does require some special procedure, including the insertion of needle electrode and the gastro-esophageal catheter¹⁵>.

Our method is very simple and safe, and does not need a special technique to apply. In fact, even the laughter of children could be measured easily. To our knowledge, this is the first report that the laughter of children was measured accurately.

Several studies have reported that the brain was activated by laughter, as seen through functional magnetic resonance imaging (fMRI) or positron emission tomography (PET)15-19>. In fact, an fMRI study showed that there were sex-specific differences in neural response to humor, implying sex-based disparities in the integration of cognition and emotion²⁰>. These results indicate that laughter activates a special area of the brain. However, even the fMRI did not quantify laughter.

Collectively, laughter has various beneficial effects on human health, including immunology, allergy, endocrinology, and cardiology2-6>. Therefore, the assessment of laughter is necessary to elucidate the mechanisms of laughter-induced effects. Unfortunately, various methods were used in the induction of laugher, so that the quantity of laughter could not be measured. Our method is the first visualization and quantification of human laughter, and thus will be useful for the study of the effects of laugher.

Acknowledgement

The authors are deeply grateful to the late Prof Yoji Kimura for his appropriate and constructive suggestions.

Reference

1 ) Cousins N. Anatomy of an illness. N Engl J Med. 1976; 205: 1458-1463.

2) Yoshino S, Fujimori J, Kohda M. Effects of mirthful laughter on neuroendocrine and immune systems in patients with rheumatoid arthritis. J Rheumatol. 1996; 23: 793-794.

3 ) Kimata H. Effect of humor on allergen-induced wheal reactions. JAMA. 2001; 285: 738.

4 ) Kimata H. Reduction of allergen-specific IgE production by laughter. Eur J Clin Invest. 2004; 34: 76-77.

5 ) Kimata H. Effect of viewing a humorous vs. nonhumorous film on bronchial responsiveness in patients with

Visualization and quantification of human laughter ( Morita · Kimata) 81

bronchial asthma. Physiol Behav. 2001; 81: 681-4.

6 ) Hayashi K, Hayashi T, Iwanaga S, et al. Laughter lowered the increase in postprandial blood glucose. Diabetes Care. 2003; 26: 1651-1652.

7) Miller M, Mangano C, Park Y, Goel R, Platnick GD, Vogel RA. Impact of Entertainment on Endothelial Function Heart. Heart. 2006; 92: 261-262.

8 ) Hayashi T, Urayama 0, Hori M, et al. Laughter modulates prorenin receptor gene expression in patients with type 2 diabetes. J Psychosom Res. 2007; 62: 703-706.

9 ) Hayashi T, Tsuji S, Iburi T, et al. Laughter up-regulates the genes related to NK cell activity in diabetes. Biomed Res.

2007;28:281-285

10) Spencer H. The Physiology of laughter. Macmillan's Magazine. 1860; 453-466.

11) Luschei ES, Rarnig LO, Finnegan EM, Baker KK, Smith ME. Patterns of laryngeal electromyography and the activity of the respiratory system during spontaneous laughter. J Neurophysiol. 2006; 96: 442-50.

12) Hoit JD, Plassman BL, Lansing RW, Hixon TJ. Abdominal muscle activity during speech production. J Appl Physiol. 1988; 65: 2656-64.

13) Hodges PW, Butler JE, McKenzie DK, Gandevia SC. Contraction of the human diaphragm during rapid postural adjustments. J Physiol. 1997; 505: 539-48.

14) Bloch S, Lemeignan M, Aguilera TN. Specific Respiratory Patterns Distinguish among Human Basic Emotions. Int J Physiol. 1991; 11: 141-154.

15) Goel V, Dolan RJ. Functional Neuroanatomy of Humor: Segregating Cognitive & Affective Components. Nature Neuroscience. 2001; 4: 237-238.

16) Meyer M, Zysset S, von Cramon DY, Alter K. Distinct fMRI responses to laughter, speech, and sounds along the human peri-sylvian cortex. Cogn Brain Res. 2005; 24: 291-306.

17) Mobbs D, Hagan CC, Azim E, Menon V, Reisss AL. Personality predicts activity in reward and emotional regions associated with humor. Proc Natl Acad Sci USA. 2005; 102: 16502-16506.

18) Dietrich S, Hertrich I, Alter K, Ischebeck A, Ackermann H. Semiotic aspects of human nonverbal vocalizations: a functional magnetic resonance imaging study. Neuroreport. 2007; 18: 1891-1894.

19) Watson KK, Matthews BJ, Allman JM. Brain activation during sight gags and language-dependent humor. Cereb Cortex. 2007; 17: 314-324.

20) Azim E, Mobbs D, Jorn B, Menon V, Reiss AL. Sex differences in brain activation elicited by humor. Proc Natl Acad Sci USA. 2005; 102: 16496-16501.

Competing interest: None declared.

The Corresponding Author has the right to grant on behalf of all authors and does grant on behalf of all authors, an exclusive license (or nonexclusive for government employees) on a worldwide basis to the BMJ Publishing Group Ltd to permit this article (if accepted) to be published in JECH and any other BMJPGL products, and sublicenses which use and exploit all subsidiary rights, as set out in our license.

Figure Legend

Figure 1. Electrocardiograms of a child and an adult in normal circumstances

Fig. lA shows the potential wave of the surface electrocardiogram of a child converted into Fourier values and lB, of an adult. C is the spectrogram of the surface electrocardiogram of the child frequency analyzed and D, of an adult.

Figure 2. Diaphragm laughter waves and laughter spectrogram of a child and an adult

Fig. 2A shows the potential laughter wave of surface diaphragm electromyogram of a child, which was converted into Fourier values and 2B of an adult. C is the spectrogram of the surface diaphragm electromyogram of a child's laughter frequency and D, of and adult.

82

Figure 3. Spectrogram of laughter, crying, sneezing, and coughing

Fig. 3A is the spectrogram of the surface diaphragm electromyogram of laughter frequency analysis; 3B, of crying;

3C, of sneezing, and 3D, of coughing.