Tactile roughness perception in the presence of olfactory and trigeminal stimulants.

Jan B.F Van Erp,Alexander Toet,Lara A Koijck

doi:10.7717/peerj.955

Abstract

Previous research has shown that odorants consistently evoke associations with textures and their tactile properties like smoothness and roughness. Also, it has been observed that olfaction can modulate tactile perception. We therefore hypothesized that tactile roughness perception may be biased towards the somatosensory connotation of an ambient odorant. We performed two experiments to test this hypothesis. In the first experiment, we investigated the influence of ambient chemosensory stimuli with different roughness connotations on tactile roughness perception. In addition to a pleasant odor with a connotation of softness (PEA), we also included a trigeminal stimulant with a rough, sharp or prickly connotation (Ethanol). We expected that—compared to a No-odorant control condition—tactile texture perception would be biased towards smoothness in the presence of PEA and towards roughness in the presence of Ethanol. However, our results show no significant interaction between chemosensory stimulation and perceived tactile surface roughness. It could be argued that ambient odors may be less effective in stimulating crossmodal associations, since they are by definition extraneous to the tactile stimuli. In an attempt to optimize the conditions for sensory integration, we therefore performed a second experiment in which the olfactory and tactile stimuli were presented in synchrony and in close spatial proximity. In addition, we included pleasant (Lemon) and unpleasant (Indole) odorants that are known to have the ability to affect tactile perception. We expected that tactile stimuli would be perceived as less rough when simultaneously presented with Lemon or PEA (both associated with softness) than when presented with Ethanol or Indole (odors that can be associated with roughness). Again, we found no significant main effect of chemosensory condition on perceived tactile roughness. We discuss the limitations of this study and we present suggestions for future research.

Highlights

When touching an object we perceive its texture through cutaneous and thermal input and by using kinesthetic, auditory, and visual cues (Lederman, 1982)
In Experiment I, we investigated the influence of ambient chemosensory stimuli with different roughness connotations on tactile roughness perception
We expected that compared to a No-odorant control condition, tactile texture perception would be biased towards (H1) smoothness in the presence of phenyl ethyl alcohol (PEA) since this odorant is typically associated with softness and femininity, and (H2) towards roughness in the presence of Ethanol since this odorant has a rough connotation due to its trigeminal nature

Summary

Introduction

When touching an object we perceive its texture through cutaneous and thermal input and by using kinesthetic, auditory, and visual cues (Lederman, 1982). The inter-modal interaction between touch and vision is, for example, shown by the fact that bimodal visual and tactile input results in superior roughness discrimination of abrasive papers (Heller, 1982), and that the visual assessment of textile roughness is less accurate in the presence of simultaneously presented incongruent tactile samples (Guest & Spence, 2003b). Tactile discrimination is to a certain degree mediated by the visual cortex (Lacey, Campbell & Sathian, 2007; Prather, Votaw & Sathian, 2004; Sathian, 2005; Sathian et al, 2011; Sathian & Zangaladze, 2002; Zangaladze et al, 1999). Visual imagery mediates and is essential for some tactile tasks (e.g., orientation discrimination: Sathian & Zangaladze, 2002; Zangaladze et al, 1999)

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