Does Binocular Disparity Facilitate the Detection of Transparent Motion?

Hibbard, Paul B.; Bradshaw, Mark F.

doi:10.1068/p2742

Cited by 28 publications

(15 citation statements)

References 31 publications

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“…An examination of signal-detection thresholds with contiguous-signal regions also allows insight into the basis of these high thresholds. In particular, though transparent-motion stimuli have been shown to require intensities of 40% for each signal, thresholds for the detection of one direction within bidirectional transparentmotion displays are between 5% and 15% (Edwards & Nishida, 1999;Hibbard & Bradshaw, 1999). This suggests that the high thresholds found using our n vs. n + 1 task result from the requirement to detect two directions simultaneously.…”

Section: Resultsmentioning

confidence: 80%

“…We have also replicated the high detection thresholds that underlie the two-signal transparent-motion capacity (Edwards & Greenwood, 2005) and extended this to the detection of spatially segregated directions. Though signal intensities were calculated differently in the two spatially segregated conditions, as dictated by performance, both required intensities around 40% for each direction, well above that required for the detection of a single direction within transparent-motion stimuli (Edwards & Nishida, 1999;Hibbard & Bradshaw, 1999). Thus, regardless of their spatial arrangement, higher thresholds are required for the simultaneous representation of two global directions than for unidirectional detection.…”

Section: Discussionmentioning

confidence: 93%

“…Because the global-motion stage contains a continuum of speed-tuned detectors, speeds that drive detectors with non-overlapping sensitivities exhibit independent signal-to-noise processing (Edwards, Badcock, & Smith, 1998;van Boxtel & Erkelens, 2006). Globalmotion signals on distinct depth planes show a similar independence, suggesting the existence of at least two systems selective for binocular disparity (Hibbard & Bradshaw, 1999;Snowden & Rossiter, 1999). The independence of these systems means that transparentmotion signals processed by one set of detectors will not reduce the intensity of signals processed by other detectors.…”

Section: Introductionmentioning

confidence: 96%

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The detection of multiple global directions: Capacity limits with spatially segregated and transparent-motion signals

Greenwood

Edwards

2009

Journal of Vision

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An important constraint on motion processing is the maximum number of directions that can be perceived at the same time. When transparent-motion stimuli are constructed based solely on direction differences, prior studies demonstrate that no more than two directions are seen simultaneously. However, this limit has been extended to three when signal directions drive independent speed- or disparity-tuned global-motion systems. The present study sought to determine whether this three-direction capacity reflects the specific mechanisms of transparent-motion detection or a more general restriction on global-motion processing. Using both transparent and spatially segregated stimuli, observers indicated which of the two intervals contained the most directions, with simultaneous processing ensured through brief durations and n vs. n + 1 signal comparisons. When spatially segregated directions were interleaved in patches, no more than two were seen, as with direction-defined transparent motion. In contrast, separating these directions into distinct spatial regions allowed the detection of up to three. Signal-detection thresholds did not vary across these signal arrangements, suggesting that the two-direction capacity results from signal-to-noise pooling across the entire stimulus, with the higher capacity for spatially distinct directions arising from independent pooling within each region. Together, these results provide further evidence for an upper capacity of three directions within the global-motion stage.

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Section: Resultsmentioning

confidence: 80%

Section: Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 96%

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The detection of multiple global directions: Capacity limits with spatially segregated and transparent-motion signals

Greenwood

Edwards

2009

Journal of Vision

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“…The addition of binocular disparity affects the perception of motion transparency in several other ways. Hibbard and Bradshaw (1999) found that signalto-noise thresholds for the detection of motion transparency improved, and approached thresholds for the detection of a single direction of motion, if transparent surfaces differed in disparity. Similarly, Calabro and Vaina (2006) found that signal-to-noise thresholds for motion transparency discrimination were affected by the combination of disparity and differences in motion direction: When surfaces differed in disparity, motion transparency could be reliably detected with smaller differences in direction.…”

Section: Introductionmentioning

confidence: 93%

Motion direction influences surface segmentation in stereo transparency

Goutcher

2016

Journal of Vision

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To perceive multiple overlapping surfaces in the same location of the visual field (transparency), the visual system must determine which surface elements belong together, and should be integrated, and which should be kept apart. Spatial relations between surfaces, such as depth order, must also be determined. This article details two experiments examining the interaction of motion direction and disparity cues on the perception of depth order and surface segmentation in transparency. In Experiment 1, participants were presented with random-dot stereograms, where transparent planes were defined by differences in motion direction and disparity. Participants reported the direction of motion of the front surface. Results revealed marked effects of motion direction on perceived depth order. These biases interact with disparity in an additive manner, suggesting that the visual system integrates motion direction with other available cues to surface segmentation. This possibility was tested further in Experiment 2. Participants were presented with two intervals: one containing motion and disparity defined transparent planes, the other containing a volume of moving dots. Interplane disparity was varied to find thresholds for the correct identification of the transparent interval. Thresholds depended on motion direction: Thresholds were lower when disparities and directions in the transparency interval matched participants' preferred depth order, compared to conditions where disparity and direction were in conflict. These results suggest that motion direction influences the judgment of depth order even in the presence of other visual cues, and that the assignment of depth order may play an important role in segmentation.

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“…This was confirmed by more recent psychophysical work on motion transparency. For example, Hibbard and Bradshaw (1999) and Snowden and Rossiter (1999) measured thresholds for the identification of the direction of motion for stimuli in which signal and noise elements were given various disparities, and they found that performance was substantially better when signal and noise had different disparities. Similarly, Edwards and Greenwood (2005) and Greenwood and Edwards (2006) showed that observers are able to detect a larger number of transparent motion directions when they are carried by signals that are distributed across distinct depth planes.…”

Section: Introductionmentioning

confidence: 98%

Disparity-based stereomotion detectors are poorly suited to track 2D motion

et al. 2012

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A study was conducted to examine the time required to process lateral motion and motion-in-depth for luminance- and disparity-defined stimuli. In a 2 × 2 design, visual stimuli oscillated sinusoidally in either 2D (moving left to right at a constant disparity of 9 arcmin) or 3D (looming and receding in depth between 6 and 12 arcmin) and were defined either purely by disparity (change of disparity over time [CDOT]) or by a combination of disparity and luminance (providing CDOT and interocular velocity differences [IOVD]). Visual stimuli were accompanied by an amplitude-modulated auditory tone that oscillated at the same rate and whose phase was varied to find the latency producing synchronous perception of the auditory and visual oscillations. In separate sessions, oscillations of 0.7 and 1.4 Hz were compared. For the combined CDOT + IOVD stimuli (disparity and luminance [DL] conditions), audiovisual synchrony required a 50 ms auditory lag, regardless of whether the motion was 2D or 3D. For the CDOT-only stimuli (disparity-only [DO] conditions), we found that a similar lag (~60 ms) was needed to produce synchrony for the 3D motion condition. However, when the CDOT-only stimuli oscillated along a 2D path, the auditory lags required for audiovisual synchrony were much longer: 170 ms for the 0.7 Hz condition, and 90 ms for the 1.4 Hz condition. These results suggest that stereomotion detectors based on CDOT are well suited to tracking 3D motion, but are poorly suited to tracking 2D motion.

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Does Binocular Disparity Facilitate the Detection of Transparent Motion?

Cited by 28 publications

References 31 publications

The detection of multiple global directions: Capacity limits with spatially segregated and transparent-motion signals

The detection of multiple global directions: Capacity limits with spatially segregated and transparent-motion signals

Motion direction influences surface segmentation in stereo transparency

Disparity-based stereomotion detectors are poorly suited to track 2D motion

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