Pop-out for illusory rather than veridical trajectories with double-drift stimuli

Özkan, Mert; Tse, Peter U.; Cavanagh, Patrick

doi:10.3758/s13414-020-02035-w

Cited by 5 publications

(5 citation statements)

References 27 publications

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“…Consequently, our results suggest that the attentional tracking system, which determines the locus of attentional selection, is influenced at some stage by the perceptual representations of target location. Our results support the view that attentional selection and tracking occur late in the visual hierarchy, after the conversion to perceptual representations of object location (He & Nakayama, 1992;Hochstein & Ahissar, 2002;Özkan, Tse, & Cavanagh, 2020;Suzuki & Cavanagh, 1995). Our data do not support models of attentional tracking that describe tracking solely as an encapsulated, low-level visual process (e.g.…”

Section: Discussioncontrasting

confidence: 54%

Attentional tracking takes place over perceived rather than veridical positions

Maechler

Cavanagh

Tse

2021

Atten Percept Psychophys

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Illusions can induce striking differences between perception and retinal input. For instance, a static Gabor with a moving internal texture appears to be shifted in the direction of its internal motion, a shift that increases dramatically when the Gabor itself is also in motion. Here, we ask whether attention operates on the perceptual or physical location of this stimulus. To do so, we generated an attentional tracking task where participants (N = 15) had to keep track of a single target among three Gabors that rotated around a common center in the periphery. During tracking, the illusion was used to make three Gabors appear either shifted away from or toward one another while maintaining the same physical separation. Because tracking performance depends in part on target to distractor spacing, if attention selects targets from perceived positions, performance should be better when the Gabors appear further apart and worse when they appear closer together. We find that tracking performance is superior with greater perceived separation, implying that attentional tracking operates over perceived rather than physical positions.

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Section: Discussioncontrasting

confidence: 54%

Attentional tracking takes place over perceived rather than veridical positions

Maechler

Cavanagh

Tse

2021

Atten Percept Psychophys

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“…later than V1; Liu, Tse, & Cavanagh, 2018) and after smooth pursuit eye movement signals have been discounted . Although these and other studies (Hui, Wang, Zhang, Tse, & Cavanagh, 2020;Liu, Yu, Tse, & Cavanagh, 2019;Özkan, Tse, & Cavanagh, 2020) demonstrate progress regarding the question where in the brain the crucial computations occur, it remains to be determined how these computations are performed. The present study focuses on one such question: how do the internal and external motion signals combine to produce the illusion?…”

Section: Introductionmentioning

confidence: 98%

Effects of internal and external velocity on the perceived direction of the double-drift illusion

et al. 2021

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In the double-drift illusion, the combination of the internal and external motion vectors produces large misperceptions of both position and direction of motion. Here, we investigate the role that speed plays in determining how these two sources of motion are combined to produce the double-drift illusion. To address this question, we measure the size of the illusion at seven internal speeds combined with six external speeds. We find that the illusion increases with increasing internal speed and decreases with increasing external speed. We model this by combining the external and internal vectors to produce the resulting, illusory direction (Tse & Hsieh, 2006). The relative effect of the two vectors is specified by a constant K in this model and the data reveal that K decreases linearly as external speed increases. This critical role of external speed in modulating the vector combination uncovers new details about how the visual system combines different sources of motion information to produce a global motion percept.

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“…Likewise, motor actions involving hand motion, such as pointing movements and tracking with a stylus, are guided by the perceived position and not the physical position ( ‘t Hart, Henriques, & Cavanagh, 2019 ; Lisi & Cavanagh, 2017 ). Moreover, it has been shown that a number of higher order perceptual and cognitive operations, including attentional tracking ( Maechler, Cavanagh, & Tse, 2021 ), pop-out effects ( Özkan, Tse, & Cavanagh, 2020 ), and the computation of apparent motion trajectories ( Hui et al, 2020 ), are all driven by the perceptual representation of the stimulus.…”

Section: Introductionmentioning

confidence: 99%

Smooth pursuit operates over perceived not physical positions of the double-drift stimulus

et al. 2021

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The double-drift illusion produces a large deviation in perceived direction that strongly dissociates physical position from perceived position. Surprisingly, saccades do not seem to be affected by the illusion ( Lisi & Cavanagh, 2015 ). When targeting a double-drift stimulus, the saccade system is driven by retinal rather than perceived position. Here, using paired double-drift targets, we test whether the smooth pursuit system is driven by perceived or physical position. Participants ( n = 7) smoothly pursued the inferred midpoint ( Steinbach, 1976 ) between two horizontally aligned Gabor patches that were separated by 20° and moving on parallel, oblique paths. On the first half of each trial, the Gabors’ internal textures were static while both drifted obliquely downward. On the second half of each trial, while the envelope moved obliquely upward, the internal texture drifted orthogonally to the envelope's motion, producing a large perceived deviation from the downward path even though the upward and downward trajectories always followed the same physical path but in opposite directions. We find that smooth pursuit eye movements accurately followed the nonillusory downward path of the midpoint between the two Gabors, but then followed the illusory rather than the physical trajectory on the upward return. Thus, virtual targets for smooth pursuit are derived from perceived rather than retinal coordinates.

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Pop-out for illusory rather than veridical trajectories with double-drift stimuli

Cited by 5 publications

References 27 publications

Attentional tracking takes place over perceived rather than veridical positions

Attentional tracking takes place over perceived rather than veridical positions

Effects of internal and external velocity on the perceived direction of the double-drift illusion

Smooth pursuit operates over perceived not physical positions of the double-drift stimulus

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