Monday, 13 June 2016

Blog: 5-month-olds multisensory perception and the development of the self

As human beings, we experience our body through sensing and acting in the surrounding environment. Throughout our daily encounters we feel our body as belonging to ourselves, we perceive our movements in a unique manner, and we are able to recognize our face as distinguished from any other face. For example, infants encountering their reflection in a mirror become familiar with their unique facial features, as well as the perfect correspondence between their performed movements and the movements seen in the reflective surface. While much attention has been given to the conceptual aspects of selfhood, such as self-awareness and consciousness, how and when the more rudimental, perceptual components that define our bodily-self originate and develop is still a matter of debate.

In the last two decades, research with adults has shown that body awareness is highly influenced by the integration of cues arising from different sensory modalities, suggesting that the combination of motor, proprioceptive, tactile, and visual signals may represent valuable precursors of body perception from the earliest stages of development. For example, in the famous rubber hand illusion, a fake hand placed in front of a person and stroked at the same time as the person’s own hand, leads to perceiving the rubber hand as belonging to oneself. In this illusion, the synchrony between visual and tactile signals produces a powerful association between the feeling of being touch and the visual stroking event. A similar trick has been applied to our most distinctive body part that is the face, suggesting that the integration of different sensory modalities might be crucial not just for our body perception, but also in the construction and update of self-recognition.
In the present study, we used facial stimuli to study 5-month-old infants’ looking behaviour in response to visual-tactile temporal synchrony. Infants watched a side-by-side video display of a peer’s face being systematically stroked on the cheek with a paintbrush. During the video presentation, the infant’s own cheek was stroked in synchrony with one video and in asynchrony with the other. Our result demonstrates that 5-month-old infants are able to discriminate between visual-tactile synchrony and asynchrony, by showing a visual preference for the synchronous facial stimulus. This finding is consistent with the possibility that some precursors of self-recognition are already present in the first 5 months of life. This study also suggests that self-specifying information is crucial in this period of development, allowing infants to differentiate between self and others. In order to confirm this hypothesis, future studies should manipulate visual appearance (self-face versus other-face) together with multisensory cues.

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