Acceleration of information processing en route to perceptual awareness in infancy.

Electrophysiological studies have suggested an acceleration in information processing in the first years of life, probably largely caused by the progressive myelination of the cortex. Here, we ask whether and how this acceleration affects information processes that contribute to perceptual awareness. We addressed this issue leveraging on the attentional blink phenomenon in infants, children, and adult participants. When two visual targets (T1 and T2) are to be detected, the observer often misses T2, if it appears shortly after T1, as if the observer's attention blinked. This phenomenon is explained by the two-stage model of perception, where an early unconscious sensory stage is followed by a late and central stage that relies on limited attentional resources. Although both T1 and T2 are processed in the earlier sensory stage, the capacity limits of the second stage are such that T2 cannot be processed as long as attention is occupied by T1. The duration of the attentional blink, thus, indexes the speed of the late processing stage of visual stimuli, which is associated with perceptual awareness. Indeed, in adults, the blink only occurs if T1 is consciously perceived but not when it is missed or processed subliminally. Accordingly, neuroimaging studies have shown that late processes blocked by T1 involve frontoparietal areas, thought to be responsible for global cognitive availability, conscious access, and reportability. Here, we show that the attentional blink is present in young infants, suggesting that the two-stage organization of perception is in place at 5 and 8 months of age. In addition, we show that the duration of the attentional blink shrinks with development, suggesting that a fundamental aspect of cognitive development is the fast acceleration of the late processing stage of perception.