Academic journal article Attention, Perception and Psychophysics

Where You Look Can Influence Haptic Object Recognition

Academic journal article Attention, Perception and Psychophysics

Where You Look Can Influence Haptic Object Recognition

Article excerpt

Published online: 8 November 2013

© Psychonomic Society, Inc. 2013

Abstract We investigated whether the relative position of objects and the body would influence haptic recognition. People felt objects on the right or left side of their body midline, using their right hand. Their head was turned towards or away from the object, and they could not see their hands or the object. People were better at naming 2-D raised line drawings and 3-D small-scale models of objects and also real, everyday objects when they looked towards them. However, this head-towards benefit was reliable only when their right hand crossed their body midline to feel objects on their left side. Thus, haptic object recognition was influenced by people's head position, although vision of their hand and the object was blocked. This benefit of turning the head towards the object being explored suggests that proprioceptive and haptic inputs are remapped into an external coordinate system and that this remapping is harder when the body is in an unusual position (with the hand crossing the body midline and the head turned away from the hand). The results indicate that haptic processes align sensory inputs from the hand and head even though either hand-centered or object-centered coordinate systems should suffice for haptic object recognition.

Keywords Haptic . Object . Recognition . Head . Visual . Gaze . Hand

We are remarkably good at recognizing everyday objects using only our hands. Haptics describes our ability to use our sense of touch to actively explore the world, as opposed to tactile processing, whichinvolves passively acquired inputs from touch. People are usually surprised at how easily they can haptically recognize objects. This typically takes just a few seconds and is accurate (Lawson & Bracken, 2011). However, relative to visual object recognition, it is generally slower and/or less accurate (Craddock & Lawson, 2009b). Furthermore, vision usually dominates over haptics in our everyday life. Vision has a larger field of view and greater acuity and allows us to recognize objects at a distance.

When we explore objects haptically, we usually also look at our hands as they touch the object. Haptics thus typically benefits from the simultaneous availability of visual information about what we are feeling. Integration of information from haptics and vision may be aided by looking at our hands as they explore an object, since thismay make it easier to align the different spatial coordinate systems that are used to encode inputs from vision and haptics, such as those centered on our head, our eyes, and our hands. As a result, haptic object recognition may be influenced by our body position. In particular, it may be easier to recognize an object if we have turned our head to look towards it. This head-towards advantage may even occur if our body position is task irrelevant-for example, if we are wearing a blindfold so that we cannot see our body or the object. The present experiments investigated whether, when relying on touch alone to recognize objects, people are influenced by the position of the object and their body or by visual inputs, despite these factors having no influence on the information available about object identity.

We are aware of only one experiment that directly investigates these visual and anatomical factors on haptic object recognition (Scocchia, Stucchi, & Loomis, 2009, described below). However, many studies have shown that spatial processing using our sense of touch is influenced by such factors. For example, Volcic, van Rheede, Postma, and Kappers (2008) asked participants to align rods held in their right and lefthands. People make large and systematic errors on this haptic orientation matching task. However, Volcic et al. found that these errors were reduced if people could see the room that they were in and if they looked towards one of their hands, even though their hands and the rods were hidden from view (see also Kaas, van Mier, Lataster, Fingal,& Sack, 2007; Newport, Rabb, & Jackson, 2002; Zuidhoek,Visser, Bredero, & Postma, 2004). …

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