Good vibrations: Global processing can increase the pleasantness of touch

Abstract

Visual–tactile carry-over effects of global/local processing (attention to the whole, versus the details) have been reported under active touch conditions. We investigated whether carry-over effects of global/local processing also occur for passive touch and whether global/local processing has differential effects on affective and discriminative aspects of touch. Participants completed two tactile tasks involving pleasantness rating and discrimination of a set of tactile vibrations before and after completing a version of the Navon task that encouraged a focus on the global (n = 30), local (n = 30), or both (n = 30) features of a series of visual stimuli. In line with previous research suggesting a link between global processing and positive emotion, global processing increased pleasantness ratings of high-frequency (but not low-frequency) tactile vibrations. Local processing did not improve the ability to discriminate between vibrations of different frequencies, however. There was some evidence of a tactile–visual carry-over effect; prior local processing of tactile vibrations reduced global precedence during the Navon task in the control group. We have shown carry-over effects of global versus local processing on passive touch perception. These findings provide further evidence suggesting that a common perceptual mechanism determines processing level across modalities and show for the first time that prior global processing affects the pleasantness of touch.

Keywords:

• Global processing
• Local processing
• Discriminative touch
• Affective touch
• Attention

Notes

¹To investigate the possibility that local processing during the Navon task affected tactile discrimination in the difficult condition, and in participants who did the tactile discrimination task immediately after the Navon task, we conducted separate 3 (Navon task group: global, local, control) between-subjects ANOVAs for each condition order group, with change in average accuracy in the difficult condition as the dependent variable. Average accuracy on the difficult condition did not differ between Navon task groups for the participants who did the discrimination task first (immediately after the Navon task), F(2, 43) = 1.71, p = .19, or for participants who did the discrimination task second (after the pleasantness rating task), F(1, 41) = 2.04, p = .14.

²Although there was a significant main effect of tactile task order when group was included as a factor (p = .003), the effect of tactile task order did not reach significance when data from the global (p = .07), local (p = .06), and control groups (p = .13) were analysed separately.

³A limitation of our discrimination task was that it included more “different” than “same” trials, which may have biased participants towards a “different” response, adversely affecting accuracy. In future research, the task could be altered to include an equal number of “different” and “same” trials to reduce bias.