Motion direction, luminance contrast, and speed perception: An unexpected meeting

Moscatelli, Alessandro; Scaleia, Barbara La; Zago, Myrka; Lacquaniti, Francesco

doi:10.1167/19.6.16

Cited by 14 publications

(11 citation statements)

References 50 publications

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“…Also, when viewing a target that oscillates back-and-forth along a circular arc, observers perceive as uniform only kinematic profiles close to harmonic motion, consistent with the assumption of a pendulum accelerated by gravity (La Scaleia et al, 2014b). Moreover, stimuli moving downward at constant speed are perceived as faster than stimuli moving upward or rightward, consistent with the hypothesis that observers combine sensory measurements with a prior assumption of approximate gravity effects (Moscatelli et al, 2019). In addition, if the visual scene is rich of contextual cues providing an environmental reference and scale, the discrimination of time duration of accelerated targets is more precise for downward motion than for upward or horizontal motion (Moscatelli and Lacquaniti, 2011).…”

Section: Introductionsupporting

confidence: 60%

Visuomotor Interactions and Perceptual Judgments in Virtual Reality Simulating Different Levels of Gravity

Scaleia

Ceccarelli

Lacquaniti

et al. 2020

Front. Bioeng. Biotechnol.

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Virtual reality is used to manipulate sensorimotor interactions in a controlled manner. A critical issue is represented by the extent to which virtual scenarios must conform to physical realism to allow ecological human-machine interactions. Among the physical constraints, Earth gravity is one of the most pervasive and significant for sensorimotor coordination. However, it is still unclear whether visual perception is sensitive to the level of gravity acting on target motion displayed in virtual reality, given the poor visual discrimination of accelerations. To test gravity sensitivity, we asked participants to hit a virtual ball rolling down an incline and falling in air, and to report whether ball motion was perceived as natural or unnatural. We manipulated the gravity level independently for the motion on the incline and for the motion in air. The ball was always visible during rolling, whereas it was visible or occluded during falling before interception. The scene included several cues allowing metric calibration of visual space and motion. We found that the perception rate of natural motion was significantly higher and less variable when ball kinematics was congruent with Earth gravity during both rolling and falling. Moreover, the timing of target interception was accurate only in this condition. Neither naturalness perception nor interception timing depended significantly on whether the target was visible during free-fall. Even when occluded, free-fall under natural gravity was correctly extrapolated from the preceding, visible phase of rolling motion. Naturalness perception depended on motor performance, in addition to the gravity level. In sum, both motor and perceptual responses were guided by an internal model of Earth gravity effects. We suggest that, in order to enhance perceptual sensitivity to physical realism, virtual reality should involve visual backgrounds with metric cues and closedloop sensorimotor interactions. This suggestion might be especially relevant for the design of rehabilitation protocols.

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Section: Introductionsupporting

confidence: 60%

Visuomotor Interactions and Perceptual Judgments in Virtual Reality Simulating Different Levels of Gravity

Scaleia

Ceccarelli

Lacquaniti

et al. 2020

Front. Bioeng. Biotechnol.

Self Cite

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“…Thus, the additional context provided by the virtual environment may have influenced participants’ speed judgements beyond what may be predicted by simple low-level visual features. Recently, Moscatelli et al ( 2019 ) suggested that biases in perceived speed may be influenced by priors for motion dynamics within a scene, which may depend on factors such as gravity and the scene medium (i.e., water or air). Accordingly, downwards moving targets with high luminance contrast were perceived as faster than upwards moving and lower contrast targets (Moscatelli et al 2019 ).…”

Section: Discussionmentioning

confidence: 99%

“…Recently, Moscatelli et al ( 2019 ) suggested that biases in perceived speed may be influenced by priors for motion dynamics within a scene, which may depend on factors such as gravity and the scene medium (i.e., water or air). Accordingly, downwards moving targets with high luminance contrast were perceived as faster than upwards moving and lower contrast targets (Moscatelli et al 2019 ). Similarly, semantics concerning the object may also have influenced the expected motion dynamics of the scene, affecting speed biases independently from the gravitational advantage.…”

Section: Discussionmentioning

confidence: 99%

Gravity prior in human behaviour: a perceptual or semantic phenomenon?

Gallagher

Török²,

Klaas

et al. 2020

Exp Brain Res

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Humans show a gravitational advantage in perception: we are more precise at judging the speed of downwards-moving than upwards-moving objects, indicating that gravitational acceleration is an internalised prior. However, it is unclear whether this gravity prior is based on purely perceptual cues or whether it can incorporate semantic knowledge. Previous research has used only objects which are known to comply with gravity, possibly confounding semantic and perceptual cues. Here we have addressed this question by asking participants to judge the speed of objects that typically move coherently with gravity (ball) or against it (rocket). Our results showed a perceptual advantage for falling stimuli, irrespective of object identity, suggesting the gravity prior is based on perceptual cues.

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“…Speed perception and distance perception are the two main topics related to driving behavior in foggy weather. As described in the second paragraph of the introduction, most studies in this field have focused on speed perception 2 , 3 , 6 – 8 , 10 , 14 , 41 , 42 and ultimately confirmed an overestimation effect of speed 2 . Admittedly, this overestimation effect of speed makes sense.…”

Section: Discussionmentioning

confidence: 84%

The foggy effect of egocentric distance in a nonverbal paradigm

Dong

Chen

Zhang

et al. 2021

Sci Rep

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Inaccurate egocentric distance and speed perception are two main explanations for the high accident rate associated with driving in foggy weather. The effect of foggy weather on speed has been well studied. However, its effect on egocentric distance perception is poorly understood. The paradigm for measuring perceived egocentric distance in previous studies was verbal estimation instead of a nonverbal paradigm. In the current research, a nonverbal paradigm, the visual matching task, was used. Our results from the nonverbal task revealed a robust foggy effect on egocentric distance. Observers overestimated the egocentric distance in foggy weather compared to in clear weather. The higher the concentration of fog, the more serious the overestimation. This effect of fog on egocentric distance was not limited to a certain distance range but was maintained in action space and vista space. Our findings confirm the foggy effect with a nonverbal paradigm and reveal that people may perceive egocentric distance more "accurately" in foggy weather than when it is measured with a verbal estimation task.

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Motion direction, luminance contrast, and speed perception: An unexpected meeting

Cited by 14 publications

References 50 publications

Visuomotor Interactions and Perceptual Judgments in Virtual Reality Simulating Different Levels of Gravity

Visuomotor Interactions and Perceptual Judgments in Virtual Reality Simulating Different Levels of Gravity

Gravity prior in human behaviour: a perceptual or semantic phenomenon?

The foggy effect of egocentric distance in a nonverbal paradigm

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