Experience can change distinct size-weight priors engaged in lifting objects and judging their weights.
2008 (English)In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 18, no 22, 1742-7 p.Article in journal (Refereed) Published
The expectation that object weight increases with size guides the control of manipulatory actions [1-6] and also influences weight perception. Thus, the size-weight illusion, whereby people perceive the smaller of two equally weighted objects to be heavier, is thought to arise because weight is judged relative to expected weight that, for a given family of objects, increases with size [2, 7]. Here, we show that the fundamental expectation that weight increases with size can be altered by experience and neither is hard-wired nor becomes crystallized during development. We demonstrate that multiday practice in lifting a set of blocks whose color and texture are the same and whose weights vary inversely with volume gradually attenuates and ultimately inverts the size-weight illusion tested with similar blocks. We also show that in contrast to this gradual change in the size-weight illusion, the sensorimotor system rapidly learns to predict the inverted object weights, as revealed by lift forces. Thus, our results indicate that distinct adaptive size-weight maps, or priors, underlie weight predictions made in lifting objects and in judging their weights. We suggest that size-weight priors that influence weight perception change slowly because they are based on entire families of objects. Size-weight priors supporting action are more flexible, and adapt more rapidly, because they are tuned to specific objects and their current state.
Place, publisher, year, edition, pages
2008. Vol. 18, no 22, 1742-7 p.
IdentifiersURN: urn:nbn:se:umu:diva-19418DOI: 10.1016/j.cub.2008.09.042PubMedID: 19026545OAI: oai:DiVA.org:umu-19418DiVA: diva2:201799