“…Similar to speech sounds and letters, optimized AV speech integration develops over the course of many years (McGurk & MacDonald, 1976; Ross et al, 2011; Sekiyama & Burnham, 2008). However, this process begins much earlier than reading, with some level of sensitivity to the congruency between the sounds of certain vowels and their corresponding articulations already present in infants as young as 2 months (Patterson & Werker, 2003) and even, it has been argued, in newborns (Aldridge, Braga, Walton, & Bower, 1999). We turn now to this literature, while keeping in mind that the acquisition of these multisensory associations might be considerably easier because 1) the speech sounds and mouth gestures are causally related, 2) audio-visual speech is encountered beginning in infancy and on a very regular basis, and 3) the learning of these relationships is largely implicit rather than explicit.…”