Measuring children's sensitivity to phonological detail using eye tracking and pupillometry.

Infants' lexical processing is modulated by featural manipulations made to words, suggesting that early lexical representations are su ciently speci ed to establish a match with the corresponding label. However, the precise degree of detail in early words requires further investigation due to equivocal  ndings. We studied this question by assessing children's sensitivity to the degree of featural manipulation (Chapters 2 and 3), and sensitivity to the featural makeup of homorganic and heterorganic consonant clusters (Chapter 4). Gradient sensitivity on the one hand and sensitivity to homorganicity on the other hand would suggest that lexical processing makes use of sub-phonemic information, which in turn would indicate that early words contain sub-phonemic detail. Studies presented in this thesis assess children's sensitivity to sub-phonemic detail using minimally demanding online paradigms suitable for infants: single-picture pupillometry and intermodal preferential looking. Such paradigms have the potential to uncover lexical knowledge that may be masked otherwise due to cognitive limitations. The study reported in Chapter 2 obtained a di erential response in pupil dilation to the degree of featural manipulation, a result consistent with gradient sensitivity. The study reported in Chapter 3 obtained a di erential response in proportion of looking time and pupil dilation to the degree of featural manipulation, a result again consistent with gradient sensitivity. The study reported in Chapter 4 obtained a differential response to the manipulation
of homorganic and heterorganic consonant clusters, a result consistent with
sensitivity to homorganicity. These results suggest that infants' lexical representations
are not only specific, but also detailed to the extent that they contain sub-phonemic
information.