Sustained representation of perspectival shape

Abstract

<jats:p>Arguably the most foundational principle in perception research is that our experience of the world goes beyond the retinal image; we perceive the distal environment itself, not the proximal stimulation it causes. Shape may be the paradigm case of such “unconscious inference”: When a coin is rotated in depth, we infer the circular object it truly is, discarding the perspectival ellipse projected on our eyes. But is this really the fate of such perspectival shapes? Or does a tilted coin retain an elliptical appearance even when we know it’s circular? This question has generated heated debate from Locke and Hume to the present; but whereas extant arguments rely primarily on introspection, this problem is also open to empirical test. If tilted coins bear a representational similarity to elliptical objects, then a circular coin should, when rotated, impair search for a distal ellipse. Here, nine experiments demonstrate that this is so, suggesting that perspectival shapes persist in the mind far longer than traditionally assumed. Subjects saw search arrays of three-dimensional “coins,” and simply had to locate a distally elliptical coin. Surprisingly, rotated circular coins slowed search for elliptical targets, even when subjects clearly knew the rotated coins were circular. This pattern arose with static and dynamic cues, couldn’t be explained by strategic responding or unfamiliarity, generalized across shape classes, and occurred even with sustained viewing. Finally, these effects extended beyond artificial displays to real-world objects viewed in naturalistic, full-cue conditions. We conclude that objects have a remarkably persistent dual character: their objective shape “out there,” and their perspectival shape “from here.”</jats:p>

A "living" supplement to: Morales, Bax, &amp; Firestone (2020) Sustained Representation of Perspectival Shape. PNAS

“…Each shelf contained four head-on elliptical coins and four circular coins (two head on, two rotated) (Figure 1.1A). Importantly, unlike Experiments 8 and 9 reported in Morales et al (2020), where the shelves were 250cm away from the far end of the table where subjects viewed the stimuli, in the present experiment (Experiment S1), the shelves were placed at an 80cm viewing distance. All the coins were carefully angled to look either head on or rotated 45º from the subject's chair at this specific viewing distance.…”

“…The setup and procedure for this experiment was almost identical to Experiment 9 in Morales et al (2020), where full details about the methods can be found. Here we summarize the most important elements of the task design and highlight the specific differences of this experiment.…”

“…1.1. Introduction Morales et al (2020) report that head-on elliptical objects are harder to find among rotated circular objects than among head-on circular objects, as indicated by slower search times. They attribute this slowdown to the perceived similarity between a head-on elliptical disk and a rotated circular disk -in particular, to that aspect of their appearance that is shared from some perspectives but not others.…”

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Morales, Bax, and Firestone (2020) reported that rotated circular objects compete for attention with head-on elliptical objects, and on this basis argued that some perspectivally shared aspect of their shape appearance is psychologically represented. Since then, a robust secondary discussion has emerged, often with suggestions for follow-up experiments and analyses.

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“…Since then, a robust secondary discussion has emerged, often with suggestions for follow-up experiments and analyses. This document is thus a "living" supplement to Morales et al (2020), reporting the results of some of these follow-ups as we conduct them. We will update the document as our work on this topic continues.…”