Laughter in response to tickling might express gender stereotypes of socio-expressive behavior in playful social interaction; involuntary muscle contractions may reflect biological components of playfulness in opposite gender constellations

The importance of skin area and gender in ticklishness. Sven Svebak. Scandinavian Journal of Psychology, June 21 2021. https://doi.org/10.1111/sjop.12756

Abstract: The importance of skin area and gender in ticklishness was explored in the present study. No previous report has been published on stimulation of the body surface exposed when dressed in a swimsuit (supine and prone positions), and the use of a feather has not been reported before. Fifty-seven university students volunteered (female N = 26, age range: 19–25, mean = 22.4; male N = 31, age range: 20–26, mean = 23.1). Sessions were videotaped for scoring of local involuntary muscle contractions (IMC) and laughter. Smiles were not scored because the face was not visible in the prone position. Subjective ticklishness was scored on a visual analogue scale. Areas that gave rise to ticklishness, were hatched onto a figure of the body. A two-factor design (gender of tickler by gender of ticklee) explored effects on dependent measures. Results showed that laughter was most frequent in female ticklees, disregarding the gender of the tickler. Subjective ticklishness and IMC scored high in opposite gender constellations. Ticklish areas included the ankles, knees, medial sides of the thighs and legs, lateral sides of the upper part of the body, elbows, the upper parts of arms, and the neck and shoulders. It was proposed that laughter in response to tickling stimulation might express gender stereotypes of socio-expressive behavior in playful social interaction, whereas IMC and subjective ticklishness may reflect biological components of playfulness in opposite gender constellations when tickled by a feather.

DISCUSSION

In general, the structure of the results supported the proposed distinction between the socio-expressive variable of laughter and the biological variables of IMC and subjective ticklishness. Laughter was more frequent in females than in males, whereas IMC scored high in opposite sex constellations, as did also the experience of the overall intensity of subjective ticklishness. It is stated in Table 2 that there was no relationship between the occurrence of IMC and laughter responses with the confounding variable of duration of the ticklish stimulation. The ANCOVAs for the IMC scores from the prone position also reflected a slightly less significant role for the gender of the tickler. It may be important to note that the significant ANCOVAs for the IMC occurred only for scores obtained in the prone (back) condition. It is possible that this type of skin stimulation relates somewhat to tickling in adult sex-related play behavior, as described in the book on erotic play by Moran (2003). However, this speculation should be left for empirical testing in the future. All subjects were within the same student population, and the laboratory may have facilitated the establishment of a protective mental frame (see Introduction) that has been proposed in reversal theory as important for the enjoyment of high arousal in the playful state and empirically supported later (see Svebak & Apter, 1987). The correlational analyses of the present findings support the validity of pleasure in the IMC where significant coefficients were calculated between laughter and IMC as well as between subjective ticklishness and IMC (Table 2). Moreover, the involuntary nature of the spontaneous IMC appeared to be similar to observations reported in previous electromyographic research that have supported a role for strong and phasic muscle responses (short-lasting, stimulus-elicited) during sensory-motor task performance in a playful mental state (Svebak, 1984).

The IMC response may be seen as a defensive evolutionary response where the aim is to rid the skin surface of an irritant by means of a local vibration. The IMC often triggers other defensive reactions as well, such as brushing and scratching of the stimulated area. Tickling most often is a pleasant sensory experience whereas itching may also involve pleasure when it is mild. However, both are mediated by the afferent pain system and, therefore, has been described as a pain-pleasure system (Mintz, 1967). In this way, laughter during ticklishness may be seen as a sociocultural signal of playfulness, whereas IMC as well as subjective ticklishness may be biological reflexes that express the paradox of mixed feelings in playfulness. Provine (2000, p. 120) discussed the social and biological complexity of the tickle stimulus and the related responses, and he pointed to the defensive movements often seen in the ticklee: “Ticklees may variously hit, kick, or wriggle to rid themselves of the stimulus.” All this may be accompanied by the contrasting behavior of hilarious laughter to encourage the tickler to continue. In this way, laughter seems to invite playful interaction whereas, at the same time, the IMC signals the opposite. The inherent paradox of ambiguity tends to increase felt arousal that is experienced as more and more pleasant with increasing arousal, provided the person is in a playful state. In contrast, it is felt as unpleasant worry or anxiety when in the serious state (Apter, 1992, 2007, 2018; Svebak & Apter, 1987).

The idea that tickle responses are signs of amusement has been discussed some years ago by Harris and Alvarado (2005), as based upon the association of smiling with humor. The relation with humor was not strongly supported in their study where smiling and laughing were also related to styles of coping with stimulation that may be experienced as slightly aversive. In general, humor, the sense of humor, laughter and smiling are all complex phenomena, and the sense of humor of an individual should not be confused with a biological trait of ticklishness. The present study did not investigate humor as a social phenomenon nor the sense of humor of the individual participant.

Recent techniques for the eliciting of ticklish responses, such as in the studies by Harris et al., appear to be more along with the gargalesis type when fingers are used, as opposed to the mild knismesis form which was used in the present study. Probably, the present study was open to playfulness because subjects were recruited on a voluntary basis, with no use of credit points that may facilitate a vicarious motive to participate, and with the use of a stimulation technique that is less invasive than is the use of fingers. In addition, the ticklers were introduced to the participants in a lecture beforehand. It is a fact that no subject asked to stop the stimulation despite the instruction to do so at any time if they felt for it.

It is often underlined that there are many different types of smiles as well as laughter. Smiles were not recorded in the present study, simply because the face was not visible in the prone position. Laughter was scored from video tapes by two independent judges who adopted a commonsense attitude toward scoring, with no further sophistication than to identify laughter as present or absent. The quality of the laughter was not scored. And a strong exhale would not be counted because it would not be accompanied by vocalization. This approach to scoring may have acted as a limitation and may explain why there were relatively few laughter reactions during the stimulation. The concordance between the two judges was almost perfect (see Method above). It is possible that important information about the distribution of responses may have been lost when facial expressiveness was not scored, and that an approach which made the face visible throughout the tickling procedure would have supported a different conclusion. However, the mapping of particularly ticklish areas all over the skin surface would not have been possible unless the subjects were stimulated also in the prone position where the face was invisible. This goal was seen as essential to the study.

The presence of a playful state during ticklishness could be validated by the use of a questionnaire at the end of the session. There are well established survey measures available to assess trait playfulness (Murgatroyd, Rushton, Apter & Ray, 1978; Svebak & Murgatroyd, 1985), but measures of state playfulness have proved to be much more difficult to validate and establish (Apter & Lewis, 2018; Desselles, Murphy & Theys, 2014). None were found to be useful in this experimental setting.

In the present study, mean scores on the subjective experience of ticklishness were slightly lover than those reported in an fMRI experiment by Carlsson, Petrovic, Skare, Petersson & Ingvar (2000) when using the same visual analog scale (66 as compared with 58 in the present experiment). This small difference may further validate the present method for eliciting ticklishness in the laboratory.

In conclusion, females appeared more often than males to respond overtly with laughter, disregarding the gender of the tickler, whereas IMC and subjective ticklishness appeared to be biological signals of play-related reflexive responses in opposite sex constellations. The precise subjective qualities of these responses should be further investigated in future research. The use of a feather for skin stimulation (knismesis: mild, soft) uncovered a complete list of locations that gave rise to the experience of ticklishness. The areas included the ankles, knees, medial sides of the thighs and legs, lateral sides of the upper part of the body, stomach, elbows, the upper part of arms, and the neck and shoulders. These areas may be different in gargalesis (vigorous, invasive) types of ticklish stimulation although they overlap well with the areas suggested by Hall and Allin (1897) based on a survey more than one hundred years ago.