Local direction of edge motion causes and abolishes the barberpole illusion

Kooi, Frank L.

doi:10.1016/0042-6989(93)90112-a

Cited by 38 publications

(22 citation statements)

References 10 publications

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“…Cutoff was found around 0.25 cycle of grating period. This is in close agreement with psychophysical studies (Power & Moulden, 1992;Kooi, 1993), which found that bias in the perceived direction was minimal with an indentation of about 0.25 cycle of the grating period (Kooi, 1993). This result suggests that similar mechanisms are involved for driving both the perception and the initiation of tracking responses (Beutter & Stone, 1997).…”

Section: Motion Integration For 2d Trackingsupporting

confidence: 91%

“…First, elongated apertures can bias the early phase of tracking eye movements in humans. Change in tracking direction exhibits the same type of dependency upon line-endings as that previously shown for perceived direction in psychophysical studies (Power & Moulden, 1992;Kooi, 1993). This suggests that the "barber pole" illusion is a low-level phenomenon, reflecting early and fast motion integration in the human visual system.…”

Section: Discussionsupporting

confidence: 74%

“…Lorenceau & Shiffrar, 1992;Shiffrar et al, 1995). Psychophysical studies of the "barber pole" illusion indeed suggest that local 1D and 2D motion signals compete to drive the motion direction perception (Power & Moulden, 1992;Kooi, 1993;Castet et al, 1999). In that sense, the "barber pole" illusion is a powerful tool to investigate surface motion processing.…”

Section: Early and Late Components Of Tracking Initiationmentioning

confidence: 99%

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Temporal dynamics of motion integration for the initiation of tracking eye movements at ultra-short latencies

et al. 2000

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The perceived direction of a grating moving behind an elongated aperture is biased towards the aperture's long axis. This "barber pole" illusion is a consequence of integrating one-dimensional (1D) or grating and two-dimensional (2D) or terminator motion signals. In humans, we recorded the ocular following responses to this stimulus. Tracking was always initiated at ultra-short latencies (Ϸ 85 ms) in the direction of grating motion. With elongated apertures, a later component was initiated 15-20 ms later in the direction of the terminator motion signals along the aperture's long axis. Amplitude of the later component was dependent upon the aperture's aspect ratio. Mean tracking direction at the end of the trial (135-175 ms after stimulus onset) was between the directions of the vector sum computed by integrating either terminator motion signals only or both grating and terminator motion signals. Introducing an elongated mask at the center of the "barber pole" did not affect the latency difference between early and later components, indicating that this latency shift was not due to foveal versus peripheral locations of 1D and 2D motion signals. Increasing the size of the foveal mask up to 90% of the stimulus area selectively reduced the strength of the grating motion signals and, consequently, the amplitude of the early component. Conversely, reducing the contrast of, or indenting the aperture's edges, selectively reduced the strength of terminator motion signals and, consequently, the amplitude of the later component. Latencies were never affected by these manipulations. These results tease apart an early component of tracking responses, driven by the grating motion signals and a later component, driven by the line-endings moving at the intersection between grating and aperture's borders. These results support the hypothesis of a parallel processing of 1D and 2D motion signals with different temporal dynamics.

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Section: Motion Integration For 2d Trackingsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 74%

Section: Early and Late Components Of Tracking Initiationmentioning

confidence: 99%

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Temporal dynamics of motion integration for the initiation of tracking eye movements at ultra-short latencies

et al. 2000

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“…The perceived direction of motion of the so-called barber pole is biased toward the long axis of the aperture, suggesting that the terminators, intersections between the grating and aperture, are used to solve the aperture problem (6,9,19). Perceived direction is biased toward the long axis because terminators signal motion parallel to the edge of the aperture and the long axis of the aperture comprises more terminators than does the short one.…”

Section: Resultsmentioning

confidence: 99%

The tactile integration of local motion cues is analogous to its visual counterpart

Pei

Hsiao

Bensmaı̈a

2008

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

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The visual and somatosensory systems have been shown to process spatial information similarly. Here we investigate tactile motion processing using stimuli whose perceptual properties have been well established in vision research, namely superimposed gratings (plaids), barber poles, and bar fields. In both modalities, information about stimulus motion (speed and direction) conveyed by neurons at low levels of sensory processing is ambiguous, a conundrum known as the aperture problem. Our results suggest that the tactile perception of motion, analogous to its visual counterpart, operates in multiple stages: first, the perceived direction of motion is determined by a majority vote from local motion detectors, which are subject to the aperture problem. As in vision, the conflict between the cues from terminators and other local motion cues is gradually resolved over time so that the perceived direction approaches the veridical direction of motion.aperture problem ͉ psychophysics ͉ plaid ͉ barber pole ͉ somatosensory B oth vision and touch share the common problem of inferring stimulus form, texture, and motion from a spatiotemporal pattern of activation across a two-dimensional sensory sheet (i.e., the retina and skin). The two systems have been found to process information about two-dimensional spatial form in a similar fashion (1-3). In both systems, information about motion can be acquired by analyzing how stimulus contours change over time. Both the visual and somatosensory systems may therefore have evolved analogous mechanisms to process motion information as well. Then again, the analogy between the two systems is not absolute: for instance, depth ordering and transparency are problems that have no obvious analogue in the cutaneous sense (although palpation through gloves may involve a tactile equivalent of transparency). Furthermore, shear forces, which have no direct visual analogue, may contribute to the tactile perception of motion (4, 5). These differences between vision and touch may lead to differences in the way the two systems process motion.The study of motion processing provides an opportunity to address an important question in sensory neuroscience, namely: how is the environment represented at each stage of perceptual processing? Indeed, the speed and direction of motion of individual (one-dimensional) edges is ambiguous because information about the motion component parallel to their orientation is not available, a predicament known as the aperture problem (6) (Fig. 1). To acquire a veridical percept of an object's direction of motion, then, it is often necessary to integrate motion information across multiple stimulus contours that differ in orientation (7,8) or to rely on so-called terminators-such as end points, corners, and intersections-whose direction of motion is unambiguous (9, 10).The aperture problem is inherent to individual neurons at low levels of processing because these neurons have spatially restricted receptive fields and only ''see'' local contours of the stimulus. From the sta...

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“…8a). In this case, the barber pole illusion is abolished, and observers perceive the grating to be moving perpendicular to its orientation (Power and Moulden, 1992;Kooi, 1993).…”

Section: Effect Of Aperture Shapementioning

confidence: 99%

Integration of Contour and Terminator Signals in Visual Area MT of Alert Macaque

Pack

Gartland²,

Born³

2004

J. Neurosci.

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The integration of visual information is a critical task that is performed by neurons in the extrastriate cortex of the primate brain. For motion signals, integration is complicated by the geometry of the visual world, which renders some velocity measurements ambiguous and others incorrect. The ambiguity arises because neurons in the early stages of visual processing have small receptive fields, which can only recover the component of motion perpendicular to the orientation of a contour (the aperture problem). Unambiguous motion signals are located at end points and corners, which are referred to as terminators. However, when an object moves behind an occluding surface, motion measurements made at the terminators formed by the intersection of the object and the occluder are generally not consistent with the direction of object motion. To study how cortical neurons integrate these different motion cues, we used variations on the classic "barber pole" stimulus and measured the responses of neurons in the middle temporal area (MT or V5) of extrastriate cortex of alert macaque monkeys. Our results show that MT neurons are more strongly influenced by the unambiguous motion signals generated by terminators than to the ambiguous signals generated by contours. Furthermore, these neurons respond better to terminators that are intrinsic to a moving object than to those that are accidents of occlusion. V1 neurons show similar response patterns to local cues (contours and terminators), but for large stimuli, they do not reflect the global motion direction computed by MT neurons. These observations are consistent with psychophysical findings that show that our perception of moving objects often depends on the motion of terminators.

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Local direction of edge motion causes and abolishes the barberpole illusion

Cited by 38 publications

References 10 publications

Temporal dynamics of motion integration for the initiation of tracking eye movements at ultra-short latencies

Temporal dynamics of motion integration for the initiation of tracking eye movements at ultra-short latencies

The tactile integration of local motion cues is analogous to its visual counterpart

Integration of Contour and Terminator Signals in Visual Area MT of Alert Macaque

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