Center-of-mass alterations and visual illusion of extent

Bulatov, Aleksandr; Bertulis, Algis; Gutauskas, Algirdas; Mickienė, Lina; Kadžienė, Gitana

doi:10.1007/s00422-010-0379-5

Cited by 13 publications

(10 citation statements)

References 44 publications

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“…For comparison, if we take as the criterion of the minimum separation between the target and the flanker two standard deviations that specify their Gaussian profiles, then the calculation (2×k) of the scale factor for grand-mean data from our current study yields a value of about 0.39. Importantly, this value closely matches the estimate (0.34±0.09) of the corresponding slope established in the previous study of the Brentano illusion evoked by stimuli composed of separate dots (Bulatov et al, 2010). However, it should be stressed that the above comparisons concern only issues of spatial scaling across retinal eccentricity, and do not imply any common base for neural mechanisms underlying different types of illusions and crowding.…”

Section: Discussionsupporting

confidence: 89%

Dependence of the filled-space illusion on the size and location of contextual distractors

Marma¹,

Bulatov²,

Bulatova³

2020

Acta Neurobiologiae Experimentalis

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For most observers, the part of the stimulus that is filled with some visual elements (e.g., distractors) appears larger than the unfilled part of the same size. This illusion of interrupted spatial extent is also known as the 'filled-space' or 'Oppel-Kundt' illusion. Although the continuously filled-space illusion has been systematically studied for over a century, there is still no generally accepted explanation of its origin. The present study aimed to further develop our computational model of the continuously filled-space illusion and to examine whether the model predictions successfully account for illusory effects caused by distracting line-segments of various lengths that are attached to different endpoints (i.e., terminators) of the reference spatial interval of the three-dot stimulus. Our experiments confirm that the illusion manifests itself along a distracting segment located both inside and outside of the reference interval. In the case of two distractors arranged symmetrically with respect to the lateral terminator, we found that the magnitude of the illusion is approximately equal to the sum of the relevant values obtained with separate distractors. The results of experiments using vertical shifts of distractors supported the model's assumption regarding the two-dimensional Gaussian profile of hypothetical areas of weighted spatial summation of neural activity. A good correspondence between the experimental and theoretical results supports the suggestion that perceptual positional biases associated with the context-evoked increase in neural excitation may be one of the main causes of the continuously filled-space illusion.

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Section: Discussionsupporting

confidence: 89%

Dependence of the filled-space illusion on the size and location of contextual distractors

Marma¹,

Bulatov²,

Bulatova³

2020

Acta Neurobiologiae Experimentalis

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“…The latter feature of the subsystem necessarily requires the normalization of its input values (to provide initial amplitude-independent conditions); it is worth mentioning here that the normalization of neural activity plays an important role in information processing at different levels of the nervous system (Reynolds and Heeger 2009, Olsen et al 2010, Carandini and Heeger 2012, Vokoun et al 2014. In turn, the output of the subsystem can be generated by means of the mechanism similar to that of a weighted spatial pooling of the neural excitation within Gaussian-shaped attentional windows (which linearly increase in width with visual eccentricity), proposed earlier to account for procedures of automatic centroid extraction in length illusions of the Müller-Lyer type (Bulatov et al 2010). Then, the contextual filling of the stimulus interval can be considered as a source of an additional distorting signal that induces (due to the increased cumulative response of the subsystem) perceptual biases in the assessment of the coordinates of relevant terminators, and thereby causes misjudgments in a length-matching task.…”

Section: Experimental Data Modelingmentioning

confidence: 99%

“…In order to resolve this issue, it seems reasonable to suppose that, due to lateral interactions, the neural representation of the original stimulus pattern can be obtained through its convolution with a Gaussian function (Bocheva andMitrani 1993, Bulatov et al 2009), the width of which in general is eccentricity-dependent. If one assumes, for the sake of simplicity, a Gaussian function with σ equal to that of the attentional window (Bulatov et al 2010), then for the stimulus with equally spaced dots in the reference interval (Fig. 1D) the corresponding one-dimensional profile of neural excitation can be described using the following formula: ,…”

Section: Experimental Data Modelingmentioning

confidence: 99%

An effect of continuous contextual filling in the filled‑space illusion

Bulatov¹,

Bulatova²,

Surkys³

et al. 2017

Acta Neurobiologiae Experimentalis

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In the filled-space (or Oppel-Kundt) illusion, the filled part of the stimulus for most observers appears longer in comparison with the empty one. In the first two experimental series of the present study, we investigated the illusory effect as a function of continuous filling (by a shaft-line segment) of the reference spatial interval of the three-dot stimulus. It was demonstrated that for the fixed length of the reference interval, the magnitude of the illusion increases non-linearly with the shaft length. For the fixed length of the shaft, the illusion magnitude gradually decreases with the lengthening of the reference interval. In the third series, psychophysical examination of the conventional Oppel-Kundt stimulus with different number of equally spaced elements (dots) subdividing its filled part was performed. Based on the analysis of the functional dependencies established, we have proposed a simple computational model that was successfully applied to fit the experimental data obtained in the present study.

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“…Some psychophysical studies' findings revealed that the perception of the spatial separation of visual objects is strongly affected by neural processes of localization of the centroids of their luminance profiles (Baud-Bovy & Soechting, 2001;Hirsch & Mjolsness, 1992;McGraw, Whitaker, Badcock, & Skillen, 2003;Watt & Morgan, 1985;Whitaker, McGraw, Pacey, & Barrett, 1996;Wright, Morris, & Krekelberg, 2011). The implementation of the concept of "centroid biases" (Morgan et al, 1990) in modeling the Müller-Lyer illusion (Bulatov, Bertulis, Bulatova, & Loginovich, 2009;Bulatov, Bertulis, Gutauskas, Mickienė, & Kadzienė, 2010) quantitatively confirmed that length misjudgments can be associated with errors in the perceptual localization of stimuli terminators. According to the model, the illusion occurs because of local processes of automatic centroid extraction (one of the options for spatial-frequency filtering through spatial convolution), which causes metric distortions of the profile of neural activity (i.e., physically change the distance between the profile peaks).…”

mentioning

confidence: 89%

Two-dimensional profile of the region of distractors’ influence on visual length judgments

Bulatov

Marma

Bulatova

2020

Atten Percept Psychophys

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In the illusion of interrupted spatial extent (also known as the filled-space or Oppel-Kundt illusion), the stimulus spatial interval filled with some visual elements (distractors) appears larger than the unfilled interval of the same size. Despite a long history of research, there is still no consensus on the origin of this visual phenomenon. It was recently shown (Bulatov, Bulatova, Surkys, & Mickienė, Acta Neurobiologiae Experimentalis, 77, 157-167, 2017) that the illusion emergence can be associated mainly with the integration of distractor-evoked effects in regions surrounding the endpoints (terminators) of the stimulus intervals. In the present study, we investigated the two-dimensional weighting profiles of these regions of distractors' influence on the magnitude of length misjudgments. We performed psychophysical experiments with three-dot stimuli that contain distracting line segments, the position of which varied either along or perpendicular to the main stimulus axis, thus scanning the profile in two orthogonal directions. It was demonstrated that for distractors shifted along the stimulus axis, the magnitude of the illusion increases to a certain maximum value with the increase of distractors displacement and smoothly decreases to zero thereafter. For distractors shifted orthogonally to the stimulus axis, the illusion magnitude monotonically decreases with the increase of distractors displacement. In the case of the distractor rotation, the greatest illusion magnitude refers to orientations of the distracting line segment along the stimulus axis and decreases to the minimum value for the orthogonal orientation. Based on the analysis of established functional dependencies, we proposed a simple quantitative interpretation of the obtained experimental data.

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Center-of-mass alterations and visual illusion of extent

Cited by 13 publications

References 44 publications

Dependence of the filled-space illusion on the size and location of contextual distractors

Dependence of the filled-space illusion on the size and location of contextual distractors

An effect of continuous contextual filling in the filled‑space illusion

Two-dimensional profile of the region of distractors’ influence on visual length judgments

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