Old and new versions of the Molyneux question: A review of experimental answers

The ‘Molyneux problem’ is typically framed in terms of the crossmodal matching of shape infor-mation from touch to vision. Indeed, shape along with intensity have commonly been consideredamodal stimulus properties/dimensions (at least by developmental researchers). However, it isimportant to note that what is common, if anything, to the senses differs in the two cases: It is thephysical stimulus (and possibly also the associated phenomenology) that is thought to be the samein the case of crossmodal (or intermodal) shape matching between touch and vision, whereas it isthe nature of the underlying neural encoding that is said to be similar in the case of crossmodalmatching of auditory and visual stimulus intensity. While the first empirical data to have beenpublished on these two forms of putatively amodal crossmodal matching appeared to suggestthat they both emerge surprisingly early in the course of human development (i.e., within thefirst month of life), certain of these seminal findings have proved difficult to replicate. Ultimately,therefore, there is currently little convincing evidence to support the notion that such putativelyinnate crossmodal matching of amodal stimulus dimensions is actually different in kind from thevarious other crossmodal correspondences that are seemingly acquired at various points duringthe course of human development (typically as a result of the internalization of the crossmodalstatistics of the environment). As such, there may be nothing particularly special about the type ofcrossmodal matching thought to underlie the ‘Molyneux problem’, and continued interest in theissue may inadvertently have helped to sustain a misguided account of the differences betweendifferent types of crossmodal correspondence.