Topography of social touching depends on emotional bonds between humans

Abstract

Nonhuman primates use social touch for maintenance and reinforcement of social structures, yet the role of social touch in human bonding in different reproductive, affiliative, and kinship-based relationships remains unresolved. Here we reveal quantified, relationship-specific maps of bodily regions where social touch is allowed in a large cross-cultural dataset (N = 1,368 from Finland, France, Italy, Russia, and the United Kingdom). Participants were shown front and back silhouettes of human bodies with a word denoting one member of their social network. They were asked to color, on separate trials, the bodily regions where each individual in their social network would be allowed to touch them. Across all tested cultures, the total bodily area where touching was allowed was linearly dependent (mean r(2) = 0.54) on the emotional bond with the toucher, but independent of when that person was last encountered. Close acquaintances and family members were touched for more reasons than less familiar individuals. The bodily area others are allowed to touch thus represented, in a parametric fashion, the strength of the relationship-specific emotional bond. We propose that the spatial patterns of human social touch reflect an important mechanism supporting the maintenance of social bonds.

Keywords: bonding; emotion; grooming; social networks; touch.

Fig. 1.

Relationship-specific TAMs across all studied countries (N = 1,368 individuals). The blue-outlined black areas highlight the taboo zones, where a person with that relationship is not allowed to touch. The data are thresholded at P < 0.05, FDR-corrected. Color bar indicates the t statistic range. Blue and red labels signify male and female subjects, respectively.

Fig. 2.

Associations between touchability and social network layer (Left), emotional bond (Middle), and lapse since last meeting a person (Right). The data are thresholded at P < 0.05, FDR corrected. Color bar indicates the r statistic range.

Fig. 3.

Least-squares regression lines for TI as a function of emotional bond in the five countries. Data points are averages of each dyadic relationship, i.e., each point denotes one person in the social network of all participants from that country. The final panel shows the countrywise regression lines together to facilitate comparisons.

Fig. 4.

Sex differences of TI for male (Left) and female (Right) subjects. Red and blue bars indicate female and male touchers, respectively.

Fig. 5.

Relationship-dependent SD maps for touching allowances (Left; from experiment 2) and t-maps for hedonic (A), tactile (B), and nociceptive (C) sensitivity from experiment 3. The r values show correlations between the relationship-dependent touching-allowance map and each of the sensitivity maps.