The aperture problem—I. Perception of nonrigidity and motion direction in translating sinusoidal lines

Nakayama, Ken; Silverman, Gerald

doi:10.1016/0042-6989(88)90052-1

Cited by 124 publications

(83 citation statements)

References 17 publications

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“…3B; see Materials and Methods). As expected from the results in previous studies (1,4), no matter what the orientation of the projected line sequence, observers always perceived directions of movement perpendicular to the line orientation. The close correspondence of the red and green arrows in Fig.…”

Section: Biased Directions Experienced When Lines Are Occluded By Apesupporting

confidence: 74%

“…This phenomenon was first studied in detail by Hans Wallach more than 70 years ago using rods that were physically moved behind apertures of various shapes (1). Because of their relevance to understanding the neural basis of motion processing, the puzzling nature of these percepts, collectively referred to as ''aperture effects,'' has attracted much attention ever since (2)(3)(4)(5)(6)(7)(8).…”

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confidence: 99%

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An empirical explanation of aperture effects

Sung

Wojtach

Purves

2009

Proc. Natl. Acad. Sci. U.S.A.

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The perceived direction of a moving line changes, often markedly, when viewed through an aperture. Although several explanations of this remarkable effect have been proposed, these accounts typically focus on the percepts elicited by a particular type of aperture and offer no biological rationale. Here, we test the hypothesis that to contend with the inherently ambiguous nature of motion stimuli the perceived direction of objects moving behind apertures of different shapes is determined by a wholly empirical strategy of visual processing. An analysis of moving line stimuli generated by objects projected through apertures shows that the directions of motion subjects report in psychophysical testing is accounted for by the frequency of occurrence of the 2D directions of stimuli generated by simulated 3D sources. The completeness of these predictions supports the conclusion that the direction of perceived motion is fully determined by accumulated behavioral experience with sources whose physical motions cannot be conveyed by image sequences as such.inverse problem ͉ motion ͉ perception ͉ vision ͉ perspective transformation W hen an object moving at a constant speed in a given direction is seen through an occluding aperture the perceived direction of movement is determined by the shape of the aperture and the orientation of the object (typically a rod or line) (see Movies S1-S3). This phenomenon was first studied in detail by Hans Wallach more than 70 years ago using rods that were physically moved behind apertures of various shapes (1). Because of their relevance to understanding the neural basis of motion processing, the puzzling nature of these percepts, collectively referred to as ''aperture effects,'' has attracted much attention ever since (2-8).The approach to rationalizing aperture effects most often cited is based on computations of local image features at the aperture boundaries. In some models, the supposition is that the visual system calculates the local velocity vectors (2, 3, 9-13). However, as generally acknowledged (3), predicting the perceptions elicited by apertures in these terms requires additional assumptions such as constant velocity fields (11-13), object rigidity (14-16), and/or ''smooth'' object motion (3,16). Other computational models have focused on the spatiotemporal energy of local features (17-22) or have used a Bayesian approach (7,8,19) to better tie theory to the observed receptive field properties of visual neurons. Whereas each of these models contends successfully with one aspect or another of the perceptual phenomenology described by Wallach, they deal with a single type of aperture, such as a circle or rectangle. Moreover, none of these existing theories provides a biological explanation for why the perceived directions of motion seen through apertures should differ systematically from the physical direction of motion.An alternative framework for understanding aperture effects, and perhaps the perceived direction of motion generally, is suggested by recent work on the percepti...

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Section: Biased Directions Experienced When Lines Are Occluded By Apesupporting

confidence: 74%

mentioning

confidence: 99%

An empirical explanation of aperture effects

Sung

Wojtach

Purves

2009

Proc. Natl. Acad. Sci. U.S.A.

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“…Figure 4. The influence of satellites on the percept of a translating ogive (Nakayama and Silverman 1988a). The rigidly translating ogive appears to be nonrigid (b) but, when a pair of translating dots are added to the display, the curve appears rigid (a).…”

Section: Effect Of Satellites Persists Over Static Backgroundmentioning

confidence: 99%

Adventures with Gelatinous Ellipses—Constraints on Models of Human Motion Analysis

Weiss

Adelson

2000

Perception

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An ellipse rotating rigidly about its center may appear to rotate rigidly or to deform nonrigidly so that it appears gelatinous. We use this ambiguous stimulus to study how motion information is propagated across space. We find that features that are quite far from the contour of the ellipse may have a strong influence on the percept of the ellipse, provided they move in a way consistent with the motion of the ellipse. We show that the percept cannot be accounted for by computational models that pool constraints over a local area only, or by models that propagate information along contours, or by models that indiscriminately propagate information across space. However, the percept can be accounted for by a class of models that assume smoothness in a layered representation.

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“…Thus, motion perception either of an infinitely long line or of a line viewed through a relatively small window cannot be determined without additional constraints. This ambiguity, known as the aperture problem, has received much attention (Adelson & Movshon, 1982;Burt & Sperling, 1981;Hildreth, 1984;Nakayama & Silverman, 1988a, 1988bPoggio, Torte, & Koch, 1985;Rock, 1981;Wallach, 1935) because any conceivable motion detection mechanism, whether biological or computational, is likely to have receptive field(s) that are limited in size.…”

Section: Absence Of Motion Informationmentioning

confidence: 99%

“…Although rigidity is certainly an important constraint, there are circumstances in which a nonrigid percept is preferred by the visual system. For example, a nonrigid interpretation occurs when another constraint is in competition with and more salient than rigidity (Braunstein & Andersen, 1984;Nakayama & Silverman, 1988a, 1988bSchwartz & Sperling, 1983;Wallach & O'ConneU, 1953). One of the assumptions underlying our work is that the effectiveness of various constraints can be evaluated by examining the competition among constraints.…”

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confidence: 99%

Percepts of rigid motion within and across apertures.

Shiffrar¹,

Pavel²

1991

Journal of Experimental Psychology: Human Perception and Perfor

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Humans consistently err in their percepts of rotational motion viewed through an aperture. Such errors provide insight into the constraints observers use to interpret retina! images. In the 1st of 2 experiments, Ss consistently perceived the fixed center of rotation for an unmarked line viewed through an aperture as located on the line, regardless of its actual location. Accuracy greatly improved with visible line endings. This finding was extended to explain why a square appears nonrigid when it rotates behind a partial occluder. This illusion may result from observers misperceiving the center of rotation of the unmarked square sides. In this situation, Ss seemed unable to apply an object rigidity constraint across apertures. These findings support a conceptualization of the visual system in which consistent local information must be clearly present before prior knowledge can be used to interpret retinal stimulation.

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The aperture problem—I. Perception of nonrigidity and motion direction in translating sinusoidal lines

Cited by 124 publications

References 17 publications

An empirical explanation of aperture effects

An empirical explanation of aperture effects

Adventures with Gelatinous Ellipses—Constraints on Models of Human Motion Analysis

Percepts of rigid motion within and across apertures.

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