Objects exhibit body model like shape distortions

Accurate knowledge about size and shape of the body derived from somatosensation is important to locate one’s own body in space. The internal representation of these body metrics (body model) has been assessed by contrasting the distortions of participants’ body estimates across two types of tasks (localization task vs. template matching task). Here, we examined to which extent this contrast is linked to the human body. We compared participants’ shape estimates of their own hand and non-corporeal objects (rake, post-it pad, CD-box) between a localization task and a template matching task. While most items were perceived accurately in the visual template matching task, they appeared to be distorted in the localization task. All items’ distortions were characterized by larger length underestimation compared to width. This pattern of distortion was maintained across orientation for the rake item only, suggesting that the biases measured on the rake were bound to an item-centric reference frame. This was previously assumed to be the case only for the hand. Although similar results can be found between non-corporeal items and the hand, the hand appears significantly more distorted than other items in the localization task. Therefore, we conclude that the magnitude of the distortions measured in the localization task is specific to the hand. Our results are in line with the idea that the localization task for the hand measures contributions of both an implicit body model that is not utilized in landmark localization with objects and other factors that are common to objects and the hand.

[1]  B. Tversky.  Distortions in memory for maps , 1981, Cognitive Psychology.

[2]  Katja Fiehler,et al.  Where are somatosensory representations stored and reactivated? , 2007, Behavioral and Brain Sciences.

[3]  A. Pressey,et al.  An extension of assimilation theory to illusions of size, area, and direction , 1971 .

[4]  Bruce Bridgeman,et al.  Does action affect perception or memory? , 2012, Vision Research.

[5]  Henry L. Roediger,et al.  Tricks of Memory , 2000 .

[6]  H. Levitt.  Transformed up-down methods in psychoacoustics. , 1971, The Journal of the Acoustical Society of America.

[7]  R. Sleight,et al.  The Horizontal-Vertical Illusion in Plane Geometric Figures , 1952 .

[8]  Thorsten Hansen,et al.  Analysis of individual variations in the classical horizontal-vertical illusion , 2010, Attention, perception & psychophysics.

[9]  Alphonse Chapanis,et al.  The vertical-horizontal illusion in a visually-rich environment , 1967 .

[10]  Timothy P McNamara,et al.  Spatial memory and perspective taking , 2004, Memory & cognition.

[11]  T M KUNNAPAS,et al.  An analysis of the vertical-horizontal illusion. , 1955, Journal of experimental psychology.

[12]  A. Caramazza,et al.  Closely overlapping responses to tools and hands in left lateral occipitotemporal cortex. , 2012, Journal of neurophysiology.

[13]  Frédérique de Vignemont,et al.  Divide et impera? Towards integrated multisensory perception and action , 2007, Behavioral and Brain Sciences.

[14]  T. Künnapas,et al.  Influence of Head Inclination on the Vertical-Horizontal Illusion , 1958 .

[15]  Patrick Haggard,et al.  Mapping the Invisible Hand : A Body Model of a Phantom Limb , 2012 .

[16]  Alfonso Caramazza,et al.  Tool Selectivity in Left Occipitotemporal Cortex Develops without Vision , 2013, Journal of Cognitive Neuroscience.

[17]  P. Haggard,et al.  Weber's illusion and body shape: anisotropy of tactile size perception on the hand. , 2011, Journal of experimental psychology. Human perception and performance.

[18]  S. Gandevia,et al.  Perceptual distortions of the human body image produced by local anaesthesia, pain and cutaneous stimulation , 1999, The Journal of physiology.

[19]  P. Brown,et al.  From innervation density to tactile acuity 1. Spatial representation , 2004, Brain Research.

[20]  Wilfried Brauer,et al.  Spatial Cognition III , 2003, Lecture Notes in Computer Science.

[21]  P. Haggard,et al.  Distorting the visual size of the hand affects hand pre-shaping during grasping , 2009, Experimental Brain Research.

[22]  Matthew R. Longo,et al.  The effects of immediate vision on implicit hand maps , 2014, Experimental Brain Research.

[23]  Patrick Haggard,et al.  An implicit body representation underlying human position sense , 2010, Proceedings of the National Academy of Sciences.

[24]  Timothy P. McNamara,et al.  How Are the Locations of Objects in the Environment Represented in Memory? , 2003, Spatial Cognition.

[25]  C. Spence,et al.  Tool-use changes multimodal spatial interactions between vision and touch in normal humans , 2002, Cognition.

[26]  A. Maravita,et al.  Tools for the body (schema) , 2004, Trends in Cognitive Sciences.

[27]  W. Matthews,et al.  Another Reason Why Adults Find it Hard to Draw Accurately , 2008, Perception.

[28]  Diane J. Schiano,et al.  Perceptual and conceptual factors in distortions in memory for graphs and maps. , 1989, Journal of experimental psychology. General.

[29]  H. Henrik Ehrsson,et al.  Being Barbie: The Size of One’s Own Body Determines the Perceived Size of the World , 2011, PloS one.

[30]  T. McNamara,et al.  Different mental representations for place recognition and goal localization , 2007, Psychonomic bulletin & review.

[31]  P. Haggard,et al.  Implicit body representations and the conscious body image. , 2012, Acta psychologica.

[32]  A. G. Fel'dman,et al.  Interaction of afferent and efferent signals underlying joint position sense: empirical and theoretical approaches. , 1982, Journal of motor behavior.