Poster #108 - Stability of Hebrew CDI Ranks: Short-Term Longitudinal Lexical Development of Hebrew-Speaking Toddlers

• In Event: 1-061 - Poster Session 02
  In Poster Session: PS 02 Section - Language, Communication

Integrative Statement

Introduction: Lexical development during the second year of life is characterized by great variability in toddlers’ rates of vocabulary growth (Fenson et al., 1994). This variability necessitates gathering information from large samples and the use of parent questionnaires is vital for this purpose. Most studies utilizing questionnaire data report on lexical ranks based on single data points in the growth curves of different participants. The present study is unique in that it reports on longitudinal data collection via parent questionnaires. The question of whether the same children maintain their percentile level throughout the second year of life is examined.

Goal: To characterize the stability of lexical rank orders during the second year of life.

Participants and procedure: Hebrew-speaking parents of 199 toddlers aged 12-24 months completed a computerized version of the Hebrew adaptation of the MacArthur-Bates Communicative Development Inventories (HCDI) every few months, as well as a background questionnaire on the toddler and parents.

Analysis: Individual Growth Curve Modelling of lexical ranks was performed. Data were controlled for age and lexical level of the first measurement.

Results: Most participants improved their lexical level rank over time (0.68 percent/month, p<.01). When age at the first measurement was taken into consideration, children for whom the questionnaire was filled out when they were 12-15 months old significantly improved their rank over time (0.81 percent/month, SD=0.36, p<.36) while children who were first measured when they were older (16-20 months) did not show a significant change in their lexical rank over time (figure 1). Children whose lexical level rank was under the median score in the first measurement significantly improved their rank over time (1.68 percent/month, SD=0.35, p<.001) (figure 2), while children whose lexical level rank was over the median score in the first measurement did not show a significant change in the rank over time. When taking both age and lexical level at the first measurement into consideration, results revealed that younger toddlers with lower initial lexical level ranks improved their rank over time more than older toddlers with higher initial lexical level rank.

Discussion: Our findings provide additional strong support to the commonly cited claim that there is great variability in children’s rate of lexical growth during the second year of life (Fenson et al., 1994). This variability is reflected not only between children, but also by the changes in the lexical level of the participants measured at different time points. The longitudinal follow-up of the same children lead to the conclusion that both age and lexicon sizes dictate the trajectory of lexical growth for a given child. Stability in rank order, which represents the relative rate of growth with reference to age, is related to the time of questionnaire administration, as well as to the size of productive vocabulary. We found that the mobility rates were higher for younger lower-ranked toddlers than it was for older higher-ranked toddlers. This finding is important in terms of comparing the percentiles of lexical levels of young toddlers for clinical as well as for research purposes.

Authors

• Hila Gendler Shalev, Kibbutzim College, Tel Aviv University
  Presenting Author

• Esther Dromi, Tel-Aviv University
  Non-Presenting Author