Project Awarded: $22,040
The concept of a visual field is useful both in phenomenological analysis as well as the scientific explanation of visual categorisation and visuomotor guidance. That is, it seems uncontroversial that visual perception ordinarily presents or represents visible stimuli as arrayed in a spatial field within which stimuli are perceived as standing in spatial relations (for discussion see Schwenkler, 2012 and Smythies, 1996). By contrast, although touch is like vision in being a spatial sense, the question whether there is a sensory field in tactile representation is not so easy to answer. In the proposed studies we aim to address this research question: Is it necessary to postulate a tactile field in order to explain the way that information about the spatial features of stimuli is extracted through tactile perception? There are several different ways that spatial information could be extracted through the sense of touch. We are particularly interested in the representation of spatial information in skin space, or the mosaic of receptive fields that are arranged like the cells of a spreadsheet or the pixels of a screen, on the surface of the skin (“skinotopic” space). When an object contacts the skin, it activates a pattern of adjacent receptive fields depending on its shape. Our research question concerns whether tactile stimuli in skin space are represented as arrayed within a spatial field. Thus defined, the concept of a tactile field in skin space is distinct from that of the spatially defined receptive fields of the skin itself: while the latter is a physiological notion, the former is a psychological construct that has its physiological underpinnings on the skin and the relevant parts in the brain. The tactile field defined as such has been studied behaviourally (Serino et al., 2008; Haggard & Giovagnoli, 2011; Fardo et al., in prep). Despite all these results, it remains unclear the extent to which the tactile field computes spatial percepts: In both the 2008 and the 2011 studies, the tactile targets are lines defined by distinct dots, while in the study in preparation the tactile targets are S shapes produced by brushes. The proposed studies will improve on these fronts as well as several others.