Choice enhances touch pleasantness

Abstract

We value what we choose more than what is imposed upon us. Choice-induced preferences are extensively demonstrated using behavioural and neural methods, mainly involving rewarding objects such as money or material goods. However, the impact of choice on experiences, especially in the realm of affective touch, remains less explored. In this study, we specifically investigate whether choice can enhance the pleasure derived from affective touch, thereby increasing its intrinsic rewarding value. We conducted an experiment in which participants were being touched by an experimenter and asked to rate how pleasant their experience of touch was. They were given either a choice or no choice over certain touch stimulus variables which differed in their relevance: some were of low relevance (relating to the colour of the glove that the experimenter would use to touch them), while others were of high relevance (relating to the location on their arm where they would be stroked). Before and during touching, pupillometry was used to measure the level of arousal. We found that having a choice over aspects of tactile stimuli-especially those relevant to oneself-enhanced the pleasant perception of the touch. In addition, having a choice increases arousal in anticipation of touch. Regardless of how relevant it is to the actual tactile stimulus, allowing one to choose may positively enhance a person's perception of the physical contact they receive.

Keywords: Affective touch; Choice; Control; Eye movement; Reward.

Fig. 1

The experiment settings and its time course. Note. a) shows the experiment settings applied to the PupilCore; b) demonstrates the pupil size recordings; c) illustrates the time course of the events of the experiment: Every frame represents a screen presented to a participant. (Colour figure online)

Fig. 2

The effect of choice, relevance, and speed on pleasantness. Note. Model-estimated means and 95% confidence intervals (CIs) for perceived pleasantness as a function of speed, choice and stimulus relevance. (Colour figure online)

Fig. 3

Model estimated pupil size in the anticipation phase as a function of choice and relevance. Note. a GAMM estimates of z-scored pupil size with 95% CIs; b GAMM estimates of z-scored and baseline-corrected pupil size (subtracting the average pupil size of the final 1 s of the preceding selection/announcement phase) with 95% CIs; c GAMM estimate of the difference between choice and no-choice conditions from (b), illustrating how the difference is significant and positive, in that the 95% CIs lie above 0, from time = −2.541 until time = 0. The red line segment at y = 0 and dotted vertical lines mark the time period where the difference is significant. For model coefficients corresponding to subfigure (a), here, see Table S4; for coefficients corresponding to subfigure (b), see Table S5. For further details, see https://osf.io/jgknx/. (Colour figure online)

Fig. 4

Model estimated pupil size in the touch phase as a function of choice, relevance, and speed. Note. a GAMM estimates of z-scored pupil size with 95% CIs, continuing the choice/no-choice difference seen at the end of the anticipation phase in Fig. 3; b GAMM estimates of z-scored and baseline-corrected pupil size (subtracting the average pupil size of the final 1 s of the preceding anticipation phase) with 95% CIs; c GAMM estimate of the difference between choice and no-choice conditions in (b), illustrating how from time = 0.509 s until time = 10 s the difference is significant and negative, in that the 95% CIs lie below 0. The red line segment at y = 0 and dotted vertical lines mark the time period where the difference is significant. For model coefficients corresponding to subfigure (a), here, see Table S6; for model coefficients corresponding to subfigure (b), see Table S7. For further details, see https://osf.io/jgknx/. (Colour figure online)