CNR - Institute of Neuroscience CNR
Institute of Neuroscience


Human Sensory System: Psychophysics of Sensory Systems

My laboratory is interested in how human sensory systems provide information about the environment and how information captured by different senses is integrated.

Dominance of vision and audition in spatial localization

The "ventriloquist effect" refers to the fact that visual stimuli (like moving puppet lips) can "capture" the apparent source of sounds. We have recently replicated this finding in the laboratory demonstrating that when visual stimuli are well localised in space vision dominate and "capture" sound; however for severely blurred visual stimuli (that are poorly localised), sound captures vision. The results are well explained not by one sense "capturing" the other, but by a Bayesian model of optimal combination of visual and auditory signals (Alais and Burr, 2004).

More recently we tested this model in more ecological conditions. An eye movement such as a saccade is a challenging event for the visual system as the information collected by the retinae has to be mapped into external world coordinates taking into account the position of gaze before and after the eye movement. In these circumstances the precision of visual localization drops dramatically however localization performance can be rescued by the presence of auditory cues. Again the combination rule conforms to a Bayesian model of sensory integration (Binda et al, 2007).


Multisensory combination and development

Adults integrate visual and haptic information in a statistically optimal fashion, weighting each sense according to its reliability. Here we show that prior to eight years of age, integration of visual and haptic spatial information does not occur, but either vision or touch dominates totally: for size discrimination, touch dominates, for orientation vision. We suggest that during development, perceptual systems require constant recalibration, for which cross-sensory comparison is important (Gori et al, 2008).


A visual sense of number

We recently demonstrated that the estimation of numerosity is a visual process that occurs in dedicated neural structures susceptible to adaptation. Perceived numerosity decreases on adapting to large numbers of dots and increases with small numbers. We suggest that numerosity is a visual qualia: just as a bunch of ripe cherries look reddish, they also look fourish. The basic building blocks of numerical abilities and arithmetic may have their roots in a basic perceptual process (Burr and Ross, 2008; Ross and Burr, 2010).


  • Gori M, Del Viva M, Sandini G, Burr DC (2008) Young children do not integrate visual and haptic form information. Curr. Biol. 18:694-8.
  • Burr D, Ross J (2008) A visual sense of number. Curr. Biol. 18:425-8.
  • Binda P, Bruno A, Burr DC, Morrone MC (2007) Fusion of visual and auditory stimuli during saccades: a Bayesian explanation for perisaccadic distortions. J. Neurosci. 27:8525-32.
  • Alais D, Burr D (2004) The ventriloquist effect results from near-optimal bimodal integration. Curr. Biol. 14:257-62.


2009 to 2014: EC - FP7 - STANIB

PRIN 2009: Italian Ministry of University and Scientific Research


  • D. Alais, University of Sydney, Sydney, Australia.
  • J. Ross, University of Western Australia, Perth, WA, Australia.
  • Liz Pellicano, Institute of Education, London, UK.
  • David Melcher, Università degli Studi di Trento, Rovereto, Italy.
  • Manuela Piazza, Università degli Studi di Trento, Rovereto, Italy.


no PI photo

David Charles Burr

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