Abstract:We report results from an experiment showing that a tall pillar with a triangular base evokes radically different three-dimensional (3D) percepts depending on the vantage point from which it is observed. The base of the pillar is an isosceles right triangle, but the pillar is perceived as just a thin plane when viewed from some vantage points. Viewed from other vantage points, the perceived 3D shape of the pillar corresponds to a square or rectangular base. In general, our results suggest that the visual syste… Show more
“…As previously argued by Ekroll, De Bruyckere, et al (2018), tricks based on perceptual illusions can be expected to be robust to repetition due to the robust and persistent nature of perceptual illusions (Firestone & Scholl, 2016;Leslie, 1988;Pylyshyn, 1999). Thus, the present findings suggest that the mechanisms underlying the illusion of absence are perceptual in nature, just like those underlying amodal completion (Ekroll, Mertens, et al, 2018;Gerbino & Zabai, 2003;Kanizsa, 1985;Michotte et al, 1964;Scherzer & Ekroll, 2015;Shimojo & Nakayama, 1990).…”
Section: Discussionsupporting
confidence: 66%
“…Thus, the claim that visual mechanisms can determine our experience of occluded regions of space is, in general principle, no more radical than the commonly accepted view that our experience of depth is determined by visual mechanisms. There is certainly contextual information in the stimulus that sometimes makes it possible to make educated guesses about what may or may not be hidden behind an occluder, and the interesting empirical question is to what extent and according to what rules and heuristics the visual system actually uses this information to make such “educated guesses.” A large body of research on amodal completion already shows that, although it may appear counterintuitive, the visual system uses such information to an impressive extent ( Ekroll, Mertens, et al., 2018 ; Ekroll et al., 2017 ; Gerbino, 2017 ; Gerbino & Zabai, 2003 ; Kanizsa, 1985 ; Koenderink et al., 2018 ; Michotte et al., 1964 ; Peta et al., 2019 ; Scherzer & Ekroll, 2015 ; Shimojo & Nakayama, 1990 ; Tse, 1999 ; Van Lier, 1999 ; Van Lier & Wagemans, 1999 ). The present findings suggest in agreement with the findings of Øhrn et al.…”
Recently, a curious illusion of absence has been described, where the space behind an occluder is compellingly experienced as empty. This illusion is similar to illusions based on amodal completion in the sense that it refers to occluded portions of a visual scene and informal observations suggest that it may also be largely impervious to conscious knowledge. The aim of the present experiment was to test the hypothesis that the illusion of absence is cognitively impenetrable in the same way as amodal completion. Participants viewed magic tricks based on amodal completion, the illusion of absence, or attentional and reasoning misdirection and tried to infer the secret behind the tricks after one, two, or three presentations. The results show that the tricks based on the illusion of absence are very difficult to debunk, even after repeated presentations. In this regard, they are similar to tricks based on amodal completion but different from tricks based on attentional and reasoning misdirection. The participants also rated how magical they felt the tricks were. Surprisingly, the magic ratings tended to be quite high even in trials where the participants had already discovered the secret behind the trick. This unexpected finding may be taken to suggest that there may be two magical moments in the lifetime of a magic trick: In addition to the magical experience evoked by trick itself, discovering the secret behind the trick may also evoke an experience of impossibility.
“…As previously argued by Ekroll, De Bruyckere, et al (2018), tricks based on perceptual illusions can be expected to be robust to repetition due to the robust and persistent nature of perceptual illusions (Firestone & Scholl, 2016;Leslie, 1988;Pylyshyn, 1999). Thus, the present findings suggest that the mechanisms underlying the illusion of absence are perceptual in nature, just like those underlying amodal completion (Ekroll, Mertens, et al, 2018;Gerbino & Zabai, 2003;Kanizsa, 1985;Michotte et al, 1964;Scherzer & Ekroll, 2015;Shimojo & Nakayama, 1990).…”
Section: Discussionsupporting
confidence: 66%
“…Thus, the claim that visual mechanisms can determine our experience of occluded regions of space is, in general principle, no more radical than the commonly accepted view that our experience of depth is determined by visual mechanisms. There is certainly contextual information in the stimulus that sometimes makes it possible to make educated guesses about what may or may not be hidden behind an occluder, and the interesting empirical question is to what extent and according to what rules and heuristics the visual system actually uses this information to make such “educated guesses.” A large body of research on amodal completion already shows that, although it may appear counterintuitive, the visual system uses such information to an impressive extent ( Ekroll, Mertens, et al., 2018 ; Ekroll et al., 2017 ; Gerbino, 2017 ; Gerbino & Zabai, 2003 ; Kanizsa, 1985 ; Koenderink et al., 2018 ; Michotte et al., 1964 ; Peta et al., 2019 ; Scherzer & Ekroll, 2015 ; Shimojo & Nakayama, 1990 ; Tse, 1999 ; Van Lier, 1999 ; Van Lier & Wagemans, 1999 ). The present findings suggest in agreement with the findings of Øhrn et al.…”
Recently, a curious illusion of absence has been described, where the space behind an occluder is compellingly experienced as empty. This illusion is similar to illusions based on amodal completion in the sense that it refers to occluded portions of a visual scene and informal observations suggest that it may also be largely impervious to conscious knowledge. The aim of the present experiment was to test the hypothesis that the illusion of absence is cognitively impenetrable in the same way as amodal completion. Participants viewed magic tricks based on amodal completion, the illusion of absence, or attentional and reasoning misdirection and tried to infer the secret behind the tricks after one, two, or three presentations. The results show that the tricks based on the illusion of absence are very difficult to debunk, even after repeated presentations. In this regard, they are similar to tricks based on amodal completion but different from tricks based on attentional and reasoning misdirection. The participants also rated how magical they felt the tricks were. Surprisingly, the magic ratings tended to be quite high even in trials where the participants had already discovered the secret behind the trick. This unexpected finding may be taken to suggest that there may be two magical moments in the lifetime of a magic trick: In addition to the magical experience evoked by trick itself, discovering the secret behind the trick may also evoke an experience of impossibility.
“…(1964), occlusion of the central region makes each outline pattern appear as a regular isosceles triangle, against the hypothesis that sensory gaps are overcome by observer’s knowledge based upon the immediate memory of the distal object. A real-life large-sized case of amodal completion in contrast with knowledge of the distal stimulus has been recently studied by Ekroll, Mertens, and Wagemans (2018). Figure 1.Cover the central part of any pattern (or of all patterns simultaneously).…”
We report two experiments on the role of mid-level processes in image
segmentation and completion. In the primed matching task of Experiment 1, a
cue→prime sequence was presented before the imperative stimulus consisting of
target shapes with positive versus negative contour curvature polarity and one
versus two axes of mirror symmetry. Priming shapes were included in two
composite occlusion displays with the same T-junction information and different
geometric features supporting a distinct balance between completion and mosaic
solutions. A cue, either congruent or incongruent with targets, preceded the
presentation of the composite priming display. Matching performance was affected
by primes in the expected direction, while cue congruency participated only in a
marginally significant three-way interaction, and prime duration had no effect.
In Experiment 2, the cue→prime sequence was replaced by a fixation cross to
control for the priming effect obtained in Experiment 1. The study confirmed
that contour connectability and curvature polarity are effective structural
factors capable of competing with symmetry in mid-level image segmentation and
completion processes.
“…Rather than being a limited topic of purely academic interest, amodal completion appears to play a pervasive role in our lives. The present special issue provides a wealth of beautiful phenomena and experimental contributions involving amodal completion, using abstract stimuli to test Gestalt-like processing, both in static displays ( Chen et al., 2018 ; Peta et al., 2019 ) and dynamic displays ( Anstis, 2018 ; Nakajima et al., 2019 ; Tyler, 2019 ), or more complex stimuli, for example, using stereoscopic fusion ( Tse, 2017a , 2017b ) or human faces ( Haberman & Ulrich, 2019 ), whereas other contributions highlight completion phenomena in a broad range of domains like art and design ( Koenderink et al., 2018 ; van Lier & Ekroll, 2019 ), magic ( Ekroll, De Bruyckere, et al., 2018 ), architecture ( Ekroll, Mertens, et al., 2018 ), fashion ( Kiritani et al., 2018 ), and even the history of astronomy ( Roncato, 2019 ). Besides that, this special issue also comprises extensive conceptual reviews from different angles: perceptual psychology ( Gerbino, 2020 ; Scherzer & Faul, 2019 ), philosophy ( Nanay, 2018 ), and neurosciences ( Thielen et al., 2019 ).…”
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