Percepts of a curved path of self-motion induced by biological motion

Hülemeier, Anna-Gesina; Lappe, Markus

doi:10.1167/jov.22.14.3270

Cited by 1 publication

(6 citation statements)

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“…Our study was motivated by previous research on heading perception in the presence of biological motion, a task we regularly encounter in daily life. While biological motion clearly disrupts the rigidity assumption that is usually made in the analysis of optic flow, recent research has shown that heading perception is nonetheless quite accurate in the presence of biological motion (Hülemeier & Lappe, 2020, 2023; Riddell & Lappe, 2018). One reason for this lies in the above-mentioned stable phases of the feet when touching the ground, which provide brief glimpses of a stable scene (Riddell & Lappe, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…While the combination of limb articulation and body translation in natural locomotion allows surprisingly accurate heading perception despite massive perturbations in the flow field (Hülemeier & Lappe, 2020; Riddell & Lappe, 2018), significant heading errors occur when only limb articulation without translation is presented (Hülemeier & Lappe, 2020; Riddell & Lappe, 2018). These heading biases might be explained by erroneous self-motion perception that results from attributing an illusory motion to the crowd based on its articulation (Hülemeier & Lappe, 2020, 2023). The present study aimed to test whether such an illusory crowd motion is perceived.…”

Section: Discussionmentioning

confidence: 99%

“…In the virtual scene, half of the group was placed 7 m and 9 m from the observer, and the other ones 14 to 18 m. Objects that are placed at different distances from the observer give rise to motion-parallax (Hanes et al, 2008; Koenderink, 1986). Motion-parallax contributes to the accurate perception of self-motion (Hülemeier & Lappe, 2023). The simulation lasted for 2500 ms.…”

Section: Methodsmentioning

confidence: 99%

“…Thought further, participants should therefore be able to accurately determine their self-motion, thus accurately discerning the absence of crowd speed. Considering the observed self-motion biases in the presence of only-articulating walkers (Hülemeier & Lappe 2020, 2023; Koerfer & Lappe, 2020; Riddell & Lappe, 2017, 2018), these heading errors may be related to backscroll illusion (Fujimoto, 2003; Fujimoto & Sato, 2006; Fujimoto & Yagi, 2008): In the backscroll illusion, when a walker articulates as if on a treadmill in front of a background, this background is perceived as moving in opposite direction than the walker faces. During self-motion, this illusory motion might indicate an additional component of self-translation or self-rotation of the observer.…”

mentioning

confidence: 99%

“…During self-motion, this illusory motion might indicate an additional component of self-translation or self-rotation of the observer. When the walkers are the only visible elements in the scene, such an illusory self-motion percept might affect the heading perception from the optic flow (Hülemeier & Lappe, 2020, 2023). This consideration, in turn, implies that the participants may alternatively deduce crowd speed from the limb articulation pattern due to their knowledge of the natural connection between limb articulation and body translation (Masselink & Lappe, 2015).…”

mentioning

confidence: 99%

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Limb articulation of biological motion can induce illusory motion perception during self-motion

Hülemeier,

Lappe

2024

i-Perception

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When one walks toward a crowd of pedestrians, dealing with their biological motion while controlling one's own self-motion is a difficult perceptual task. Limb articulation of a walker is naturally coupled to the walker's translation through the scene and allows the separation of optic flow generated by self-motion from the biological motion of other pedestrians. Recent research has shown that if limb articulation and translation mismatch, such as for walking in place, self-motion perception becomes biased. This bias may reflect an illusory motion attributed to the pedestrian crowd from the articulation of their limbs. To investigate this hypothesis, we presented observers with a simulation of forward self-motion toward a laterally moving crowd of point-light walkers and asked them to report the perceived lateral speed of the crowd. To investigate the dependence of the crowd speed percept on biological motion, we also included conditions in which the points of the walker were spatially scrambled to destroy body form and limb articulation. We observed illusory crowd speed percepts that were related to the articulation rate of the biological motion. Scrambled walkers also produced illusory motion but it was not related to articulation rate. We conclude that limb articulation induces percepts of crowd motion that can be used for interpreting self-motion toward crowds.

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