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

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.

Trapped in a tight spot: Scaling effects occur when, according to the action-specific account, they should not, and fail to occur when they should

“…Furthermore, this change was perceived by participants: In the action capacity task, participants estimated the minimum passable aperture for their padded hand as being wider than that for their unpadded hand. The latter result is consistent with previous results (Collier & Lawson, 2017b ; Ishak et al, 2008 ) showing that participants appropriately recalibrate their perceived action capacity following a change in the functional morphology of their hands. Of most interest theoretically was the perceptual task.…”

“…As a consequence, some of the participants may, for example, have decided that they should use their visible hand as an anchor for estimating the aperture width. Since right-handers believe that their right hand is larger than their left hand (Collier & Lawson, 2017b ; Linkenauger et al, 2011 ), this strategy could explain the results that we obtained.…”

“…The aperture apparatus, gloves, and method for measuring perceived aperture passability in the action capacity task were closely based on the methods of Ishak et al ( 2008 ). The visual matching method used in the perceptual task was the same as that used in other work investigating the action-specific account (e.g., Collier & Lawson, 2017a , b ; Linkenauger et al, 2011 , b ).…”

“…Instead, it is possible that this effect arose because of the demand characteristics associated with telling participants whether to use their left or right hand on each trial of the perceptual task. Previous work has suggested that the demand characteristics associated with an unexplained manipulation can be reduced by using a cover story (Collier & Lawson, 2017b ; Durgin et al, 2009 ; Durgin, Klein, Spiegel, Strawser, & Williams, 2012 ; Firestone & Scholl, 2014 ). Therefore, if the effects found in Experiment 1 were the result of demand characteristics, they might be eliminated by providing a cover story.…”

“…However, there are a number of concerns with the action-specific account (e.g., Collier & Lawson, 2017a , b ; Durgin et al, 2009 ; Firestone, 2013 ). For example, Firestone and Scholl ( 2014 ; see also Firestone & Scholl, 2016 ) argued that this account relies on an overly confirmatory research strategy—that is, predicting and then finding a given effect.…”