Integration of visual and inertial cues in perceived heading of self-motion

Abstract

In the present study, we investigated whether the perception of heading of linear self-motion can be explained by Maximum Likelihood Integration (MLI) of visual and non-visual sensory cues. MLI predicts smaller variance for multisensory judgments compared to unisensory judgments. Nine participants were exposed to visual, inertial, or visual-inertial motion conditions in a moving base simulator, capable of accelerating along a horizontal linear track with variable heading. Visual random-dot motion stimuli were projected on a display with a 40° horizontal × 32° vertical field of view (FoV). All motion profiles consisted of a raised cosine bell in velocity. Stimulus heading was varied between 0 and 20°. After each stimulus, participants indicated whether perceived self-motion was straight-ahead or not. We fitted cumulative normal distribution functions to the data as a psychometric model and compared this model to a nested model in which the slope of the multisensory condition was subject to the MLI hypothesis. Based on likelihood ratio tests, the MLI model had to be rejected. It seems that the imprecise inertial estimate was weighed relatively more than the precise visual estimate, compared to the MLI predictions. Possibly, this can be attributed to low realism of the visual stimulus. The present results concur with other findings of overweighing of inertial cues in synthetic environments.

Visual and vestibular perceptual thresholds each demonstrate better precision at specific frequencies and also exhibit optimal integration

“…Since at least some studies caution that the way visual cues are presented can disrupt optimal integration (Butler et al 2011;de Winkel et al 2010), it was important to utilize a natural visual scene and manipulate thresholds by changing the motion frequency. This contrasts with prior approaches in which one cue is artificially degraded to alter its precision, as in some self-motion perception studies (Butler et al 2010;Fetsch et al 2009Fetsch et al , 2012Gu et al 2008) and other multisensory integration studies (e.g., Ernst and Banks 2002;Landy et al 1995).…”

Navigating virtual mazes: The benefits of audiovisual landmarks

“…Virtual environments can be more complex than natural environments with respect to their scale [4,2], structural complexity and dimensionality [5]. Furthermore, virtual environments often differ from natural environments with respect to the sensory modalities involved, depending on the use of visual, auditory and vestibular displays [6,7,8,9,10,11] and interaction methods [8]. Thus, an optimal support of human spatial navigation in virtual environments relies on knowing the effects of involving multiple sensory modalities.…”

How Optic Flow and Inertial Cues Improve Motion Perception

“…Psychophysical studies of heading discrimination using two-alternative forcedchoice tasks have reported vestibular heading discrimination thresholds in darkness that are as small as a few degrees Fetsch et al 2009;Butler et al 2010Butler et al , 2015de Winkel et al 2010;Drugowitsch et al 2014). Such threshold values are comparable (although larger) with those described in visual heading discrimi-nation tasks (Warren and Hannon 1990;Royden et al 1992;van den Berg and Brenner 1994;Stone and Perrone 1997).…”