Olfactory-tactile compatibility effects demonstrated using a variation of the Implicit Association Test

We investigated whether the crossmodal associations between olfaction and touch reported previously in studies involving subjective report measures could also be demonstrated using an indirect measure of crossmodal association. To this end, we used a modified version of the Implicit Association Test. The participants had to make speeded discrimination responses to a series of unimodally presented olfactory (lemon vs. animal odour) or tactile stimuli (soft vs. rough fabric) using two response keys. In compatible blocks of trials, the olfactory and tactile stimuli that were mapped onto the same response key were considered to share a stronger association (e.g., the lemon odour and the soft fabric) than those that were combined onto the same response key in the incompatible blocks of trials (e.g., the animal odour and the soft fabric). The results showed that the participants responded significantly more rapidly in the compatible response mapping blocks than in the incompatible blocks, thus confirming the existence of associations between the stimuli that were considered to be compatible. These results provide the first empirical evidence that olfactory-tactile crossmodal associations are stable enough to influence performance even when not directly relevant to a participant's task.