Alexandre Lehmann

I am currently completing a Phd in cognitive science about “the role of the auditory modality in spatial orientation mechanisms”, under the supervision of Pr Alain Berthoz. My current field is human space perception, studying the mechanisms of multisensory integration (specifically those involving audition) that grant unity and coherence of the perceived world.

The various sensory modalities have long been regarded as independent modules performing a specific processing and communicating with a limited number of multimodal associative areas. Nevertheless our perception of the world is intrinsically multisensory. A large amount of results – from psychology to neurophysiology – have demonstrated that the processing performed by so-called “unimodal” areas can be highly modulated by other sensory modalities, even for very early processing areas such as the primary auditory cortex. A robust and ecological understanding of a sensory modality system thus requires to take into account its interaction with other modalities. Our unified and coherent awareness of space is the result of very complex processes but is yet unfolding to us in everyday life in an unnoticed, automatic fashion.

How are combined the various sensory information allowing us to locate our body in space and update our position as we move ? Is there an amodal perceived space or a wide range of poly-sensory spaces dedicated to specific actions ?

I am developing a multi-disciplinary study of multisensory integration and binding, in a perception-action framework, with a strong focus on the auditory modality. I use an experimental approach based on the use of multimodal (visual, auditory and vestibular) virtual reality (VR) in an action-perception framework. Psychophysical paradigms are carried out in virtual worlds where usual reality can be highly altered and each parameter finely tuned.

A deficit of coherent space integration could for instance bring up a disintegration of the body in space, challenging processes of self consciousness and embodiement, it could also lead to cognitive fragmentation such as observed in autistic and schizophrenic disorders. Thus I see the study of phenomena such as synesthesia and hallucinations as a great tool to bridge the gap between first and third person approaches and to complete the puzzle of consciousness.

I am currently very interested in oscillatory theories and models of consciousness and how they shed new light on multisensory research and on altered states of consciousness such as autoscopic phenomena, hypnagogic states and various hallucinations observed for instance in schizophrenic patients.

Keywords : hallucinations - space perception - auditory, vestibular & visual system – binding - self awareness – virtual reality – experimental psychology – mental rotations – multisensory research.

Lehmann, A. ; Vidal,M. ; Bülthoff, H.H. (2007) Updating spatial knowledge during self-motion: towards a sensory interpretation of the allocentric contribution . Submitted to Cognition.

Lehmann, A. ; Vidal, M. & Bülthoff, H.H. (2007) A high-end virtual reality setup for the study of mental rotations . Submitted to Presence.

Lehmann, A. ; Ducrot, V. & Berthoz, A. (2006) Acoustic Information Selectively Enhances Route Spatial Memory In Humans: A Virtual Reality Study . Submitted to Spatial Cognition & Computation.

Lehmann, A . ; Vidal, M. ; Bülthoff, H.H. & Berthoz, A. (2007) Combining sensory cues for spatial orientation: Assessing the contribution of different modalities in the facilitation of mental rotations. European Workshop on Imagery and Cognition, 26-29 June 2007, Utrecht.

Lehmann, A . ; Ducrot, V., Fuchs, P.; & Berthoz,A. (2006) Multisensory landmarks improve route memory performance in humans : a virtual reality study . International Multisensory Research Forum, 18-21 Juin 2006, Dublin .

L afon M., Panagiotaki P., Lehmann A ., Berthoz A. (2005) Les stratégies cognitives dans l'encodage spatial d'un trajet navigué chez l'homme : Etude de psychologie cognitive en réalité virtuelle . CJCSC 2005 .

Lehmann, A. ; Panagiotaki, P., Fuchs, P.; & Berthoz,A., (2005) Bimodal acoustic-visual virtual reality applied to the study of cognitive strategies during navigation . 24-25 Novembre 2005 Senlis, (France).

Lehmann, A ; Panagiotaki, P.; & Berthoz, A (2005) Role of Semantic Congruence in Multisensory Landmark use for spatial navigation : a virtual reality study . Forum des Laboratoires en Sciences Cognitives, 15 avril 2005, Paris.

Panagiotaki, P.; Diard, J.; Lehmann, A .; & Berthoz, A. (2004) Hierarchical Cognitive Mechanisms of Memory encoding during Spatial Navigation in Humans: Psychophysical Studies with Virtual Reality. 12 ième Congrès International de Psychophysiologie, 18-23 septembre 2004, Thessalonique, Grèce.

Lehmann, A .; Panagiotaki, P.; & Berthoz, A (2004) Utilisation de repères audio-visuels dans la navigation chez l'homme : quelle influence sur la mémoire spatiale . 9ieme Colloque ARCo, Compiègne, 8-10 décembre 2004.

Panagiotaki, P.; Lafon, M.; Lehmann, A .; & Berthoz, A. (2004) Stratégies Cognitives Fondamentales de la Mémoire Spatiale pendant la Navigation des trajets mémorisés chez les Humains : Une Etude en Réalité Virtuelle. 9ieme Colloque ARCo, Compiègne, 8-10 décembre 2004.

Laboratoire de Physiologie de la Perception et de l'Action

UMR 7152 Collège de France - CNRS