Human infants are able to combine visual and proprioceptive target information in reaching

Actions are based on estimations about world and bodily states, which are derived from partially redundant noisy sensory signals. To reduce the impact of sensory noise, signals from various senses are combined in a Bayes optimal manner in adults. In children, multisensory integration has been typically found to be Bayes optimal from 8 to 10 years of age and beyond. Implication for early motor development might be that infants base their actions on only one sensory modality, or, potentially, infants do already combine the senses in some - though likely suboptimal - way. Here, 7-month-old infants reached for an object they could localize based on vision, on proprioception or on both modalities. The quantity (success rate) and quality of reaches (number of speed peaks, the fewer the better) were assessed. Both quantity and quality of reaches were significantly higher in the multisensory condition compared to both of the unisensory conditions. These data provide evidence for combined use of multiple senses in infancy.