Spatial localization of touch in the first year of life: Early influence of a visual spatial code and the development of remapping across changes in limb position.

Abstract

Two experiments investigated infants' ability to localize tactile sensations in peripersonal space. Infants aged 10 months (Experiment 1) and 6.5 months (Experiment 2) were presented with vibrotactile stimuli unpredictably to either hand while they adopted either a crossed-or uncrossed-hands posture. At 6.5 months, infants' responses were predominantly manual, whereas at 10 months, visual orienting behavior was more evident. Analyses of the direction of the responses indicated that (a) both age groups were able to locate tactile stimuli, (b) the ability to remap visual and manual responses to tactile stimuli across postural changes develops between 6.5 and 10 months of age, and (c) the 6.5-month-olds were biased to respond manually in the direction appropriate to the more familiar uncrossed-hands posture across both postures. The authors argue that there is an early visual influence on tactile spatial perception and suggest that the ability to remap visual and manual directional responses across changes in posture develops between 6.5 and 10 months, most likely because of the experience of crossing the midline gained during this period.

Perception of visual-tactile colocation in the first year of life.

“…Bremner et al (2008) find that this is not present at 6 months but develops by 10 months of age. There are a range of differences between the procedure used by Bremner et al (2008), and that used in the current study which might explain the different ages at whcih infants demonstrated competence.…”

“…Indeed, as a result of eye movements, these computational challenges also impinge on our ability to detect co-location between visual and auditory stimuli (Pöppel, 1973). Research with infants indicates that an ability to incorporate information about posture into sensory processing develops gradually across the first year of life (e.g., Bremner et al, 2008; …”

“…Previous research investigating the ability to coordinate visual and tactile space has only looked at crossmodal visual orienting to tactile stimuli (Bremner et al, 2008). Here…”

“…Results indicate that infants of both age groups demonstrate a spontaneous visual preference for spatially separate over co-located visual and tactile stimuli presented to their hands. Thus, infants are sensitive to spatial co-location between visual and tactile cues from at least 6 months of age, and before they are able to orient visually to tactile stimuli presented in isolation (Bremner et al, 2008) On first consideration it may seem unsurprising that 6-month-olds, who are generally able to grasp and haptically explore objects, also demonstrate an ability to recognise whether tactile and visual stimuli originate from a single spatial location. Indeed, infants and even newborns show emerging abilities to map tactile to visual patterns in crossmodal transfer tasks (e.g., Bryant et al, 1976;Rose, 1994;Streri, 2012).…”

“…However, it is our contention that an ability to perceive co-location among sense modalities is a more complex attainment than recognising a spatial pattern across modalities. Co-locating tactile and visual stimuli on the hands requires infants to locate each stimulus with respect to a common frame of reference which is neither exclusively related to sensory or to external frames of reference (Bremner et al, 2008). As such, evidence of sensitivity to visual-tactile co-location is more indicative of an ability to represent sensory information with regard to the external world (Eilan, 1993) and the interface between the body and the external world (Bremner et al, 2008).…”