It's out of my hands! Grasping capacity may not influence perceived object size.

Elizabeth S Collier,Rebecca Lawson

doi:10.1037/xhp0000331

Elizabeth S Collier, Rebecca Lawson

Open Access

https://doi.org/10.1037/xhp0000331

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Abstract

Linkenauger, Witt, and Proffitt (2011) found that the perceived size of graspable objects was scaled by perceived grasping capacity. However, it is possible that this effect occurred because object size was estimated on the same trial as grasping capacity. This may have led to a conflation of estimates of perceived action capacity and spatial properties. In 5 experiments, we tested Linkenauger et al.’s claim that right-handed observers overestimate the grasping capacity of their right hand relative to their left hand, and that this, in turn, leads them to underestimate the size of objects to-be-grasped in their right hand relative to their left hand. We replicated the finding that right handers overestimate the size and grasping capacity of their right hand relative to their left hand. However, when estimates of object size and grasping capacity were made in separate tasks, objects grasped in the right hand were not underestimated relative to those grasped in the left hand. Further, when grasping capacity was physically restricted, observers appropriately recalibrated their perception of their maximum grasp but estimates of object size were unaffected. Our results suggest that changes in action capacity may not influence perceived object size if sources of conflation are controlled for.

Highlights

Public Significance Statement The action-specific account of perception suggests that an observer’s capacity for action scales how the environment appears to them and, how they perceive its spatial properties
Further evidence for the action-specific account comes from the claim that right-handed participants underestimate the size of objects they intend to grasp with their right hand relative to objects they intend to grasp with their left hand (Linkenauger, Witt, & Proffitt, 2011; see Linkenauger et al, 2010)
Having confirmed that right handers perceive their right hand as larger than their left hand in Experiment 1, in Experiment 2 we went on investigate whether this effect would lead to the size of objects grasped by the right hand being underestimated relative to those grasped by the left hand (Linkenauger et al, 2011)

Summary

Introduction

Public Significance Statement The action-specific account of perception suggests that an observer’s capacity for action scales how the environment appears to them and, how they perceive its spatial properties. Sugovic, Turk, and Witt (2016) recently pointed out that if actionspecific scaling effects are driven by real, physical body morphology (e.g., actual weight) rather than beliefs or thoughts about the body, these effects are, compatible with the idea of cognitive impenetrability This is because information about the physical abilities of the body—rather than conscious beliefs or thoughts—is influencing perception, possibly through multimodal processes. Sugovic et al (2016) found that only actual weight, and not beliefs or perceptions about body mass, predicted action-specific scaling effects—in this case, distances were estimated as greater by heavier observers This finding, namely that only actual, and not perceived, body morphology influenced spatial estimates contrasts to Linkenauger et al.’s (2011) finding that it was people’s perceptions of their grasping capacity that scaled their estimates of object size, whereas their actual grasping capacity did not differ between the right and left hands

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