2 - Perception of space: Orientation and Localization
A first set of data obtained in darkness strongly suggested that the vestibular system cannot be considered as an accurate graviceptor in quasi-static conditions at a perceptual level, as it is usually mentioned in the literature (Bringoux et al., 2003). Conversely, gravity-related somatosensory inputs appeared of prime importance for perceiving static body orientation without visual cues (Bringoux et al. 2002). The efficiency of vestibular cues can nevertheless be improved through a specific training to compensate for the lack of visual and somatosensory cues (Bringoux et al., 2001).
We also showed that the perception of earth-based (geocentric) references, such as the subjective visual horizon (SVH) or the subjective proprioceptive horizon (SPH), is linearly influenced by pitch body tilts (Bringoux et al., 2004, 2008), and that these references are involved in the perceived passability under high obstacles (Bourrelly et al., 2009, 2010, 2011).
Other results recently obtained in a full-immersive environment emphasize the significant influence of the structure of tilted visual scenes in the perceived verticality of objects. Specifically, the more the visual scene contained geometrical and meaningful 3D features, the greater the "rod-and-frame effect" (RFE) upon subjective vertical estimates. The RFE was however reduced when the judgement of verticality implies visuo-kinesthetic inputs, as compared with visual-only estimates (Bringoux et al., 2009).
3 - Sensorimotor consequences of force field perturbations
Accurate motor control allows human beings to produce pointing and reaching movements with great accuracy in a large variety of environmental conditions.
We demonstrated that goal directed arm movements were nevertheless affected by gravitational force level (Scotto di Cesare et al., 2011), as well as by visual inputs inducing illusory gravitational changes (Bringoux et al., 2012a, Scotto di Cesare et al., revised) but might be almost restored through specific somatosensory stimulation (Bringoux et al., 2012b; Carriot et al., 2004).
We also reported on the effectiveness of visual information relative to static hand position prior to movement onset on the adaptive changes observed in a gravito-inertial disturbing force field (Bourdin et al., 2006). Furthermore, we showed that motor adaptation to a modified force field is possible without proprioception and that vision can compensate for the permanent loss of proprioception to update the central representation of limb dynamics (Sarlegna et al., 2010).
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4 - Application: perceptual and motor behavior of drivers and pilots
[Les pilotes conduisent aussi avec la tete]
Transportation Research Group