Abstract
Vection is an illusory perception of self-motion that can occur when visual motion fills the majority of the visual field. This study examines the effect of the duration of visual field movement (VFM) on the perceived strength of self-motion using an inertial nulling (IN) and a magnitude estimation technique based on the certainty that motion occurred (certainty estimation, CE). These techniques were then used to investigate the association between migraine diagnosis and the strength of perceived vection. Visual star-field stimuli consistent with either looming or receding motion were presented for 1, 4, 8 or 16s. Subjects reported the perceived direction of self-motion during the final 1s of the stimulus. For the IN method, an inertial nulling motion was delivered during this final 1s of the visual stimulus, and subjects reported the direction of perceived self-motion during this final second. The magnitude of inertial motion was varied adaptively to determine the point of subjective equality (PSE) at which forward or backward responses were equally likely. For the CE trials the same range of VFM was used but without inertial motion and subjects rated their certainty of motion on a scale of 0–100. PSE determined with the IN technique depended on direction and duration of visual motion and the CE technique showed greater certainty of perceived vection with longer VFM duration. A strong correlation between CE and IN techniques was present for the 8s stimulus. There was appreciable between-subject variation in both CE and IN techniques and migraine was associated with significantly increased perception of self-motion by CE and IN at 8 and 16s. Together, these results suggest that vection may be measured by both CE and IN techniques with good correlation. The results also suggest that susceptibility to vection may be higher in subjects with a history of migraine.
Highlights
Vection is an illusory perception of motion that may occur when a moving visual stimulus fills the majority of the visual field [1]
Subject-reported certainty estimates of self-motion for visual fore-motion trials are shown (Fig 8), Overall, longer durations of visual motion significantly increased the certainty estimate, with significant differences noted between visual field movement (VFM) durations of 1s, 4s, and 8s stimuli (One-way ANOVA, F = 5.88, p = 0.004)
The current study examined vection induced by the same VFM stimulus using two different measures
Summary
Vection is an illusory perception of motion that may occur when a moving visual stimulus fills the majority of the visual field [1]. Several studies have attempted to quantify vection, primarily with magnitude estimation, where the subject assigns a subjective numeric value to their perception [6,7,8,9,10,11] This technique is simple to implement, due to the subjective nature of the reporting it is difficult to determine if differences in subject responses are due to differences in underlying perception or to differences in the interpretation of the stimulus in relation to the reporting scale [12,13,14]. Vection magnitude estimate techniques can vary between studies, making them difficult to compare [6,11,15] These problems have been addressed in the past by normalizing responses across subjects [16], but this solution assumes all subjects had the same underlying perception, which may not be the case. Attempts have been made to calibrate magnitude estimates based on inertial motion [17,18], this becomes problematic as sequentially presented stimuli may be difficult to match due to adaptation and working memory constraints
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