2018 Friday Poster 6665

Friday, November 2, 2018 | Poster Session I, Metcalf Small | 3pm

Building lexico-semantic networks impacts early word recognition
A. Borovsky, R. Peters

Adult lexicons encode rich semantic relations between words at multiple levels. To illustrate, an individual word, such as ostrich may belong to a broader category with many interconnected semantic neighbors (ANIMALS), though ostrich itself may have relatively few direct semantic neighbors. The multi-layered nature of adult semantic networks, in conjunction with the surrounding semantic context, influences lexical recognition by alternatively facilitating and interfering with word recognition (Chen and Mirman, 2012). For example, gaze measures of adult word recognition are slower (denoting lexical interference) when a labeled target object is accompanied by an unlabeled semantically-related (vs. semantically-unrelated) distractor object (Huettig and Altmann, 2006). Similarly, at the outset of language development, infant lexical recognition is slowed by the presence of related distractor object (Bergelson and Aslin, 2017). However, children vary tremendously in the content and size of their early lexicons, and relatively little is known regarding how variability in vocabulary size and structure impacts lexical processing.

We explored the emergence of these processing dynamics in a large group of 18-month-old children (N = 71) who had significant variability in the size (10-274 words) and structure of their productive lexicons. We calculated semantic structure in each toddler’s productive lexicon (measured via MBCDI) using graph-theoretic metrics at multiple granularities (neighborhood- level, word-level, and lexicon-level). Neighborhood-level structure was calculated as a function of the child’s own semantic category knowledge, while word-level structure reflected the number of direct semantic neighbors produced by each child (i.e. word degree). Lexicon-level structure was denoted as a global clustering co-efficient (GCC) metric that characterizes the overall connectivity of each toddler’s productive vocabulary.

To explore whether and how these different levels of semantic structure impact real-time dynamics in lexical recognition, toddlers completed an eye-tracked word recognition task containing semantically unrelated and related picture contexts (Fig 1-3). Linear-mixed effects regression analyses indicated that semantic structure influenced lexical processing only in toddlers with relatively larger vocabularies (productive vocabulary > 59 words, defined by median split). Namely, in this higher-vocabulary group, items with high word-degree (many direct semantic neighbors) facilitated recognition in unrelated contexts (β=0.037, SE=0.018 p=.044), while higher-level structure (lexicon-level/GCC, and neighborhood-level/category density) was associated with semantic interference in related trials (GCC: β=-2.74, SE=1.38, p=.048, category density: β= -0.45, SE=0.17, p=.0083). The results highlight several important findings. First, semantic structure at multiple granularities is detectable even in children with relatively small productive vocabularies. However, these varying layers of structure do not differentially impact lexical processing until learners acquire a sizeable vocabulary numbering at least several dozen words. Secondly, the general pattern in our findings suggest that in toddlers, more macro-level connectivity (at neighborhood and lexicon-level) are important in developing lexical interference, whereas lower-levels of structure (among direct lexical neighbors) promote lexical facilitation. These findings motivate a need to develop theoretical accounts of word recognition that focus not only the timing of lexico-semantic network building, but also how individual differences in lexical-semantic growth and structure impact this process.

References

Bergelson, E., & Aslin, R. N. (2017). Nature and origins of the lexicon in 6-mo-olds. Proceedings of the National Academy of Sciences, 114(49), 12916-12921.

Chen, Q., & Mirman, D. (2012). Competition and cooperation among similar representations: toward a unified account of facilitative and inhibitory effects oflexical neighbors. Psychological Review, 119(2), 417-30.

Huettig, F., & Altmann, G. T. (2005). Word meaning and the control of eye fixation: Semantic competitor effects and the visual world paradigm. Cognition, 96(1), B23-B32.