Tense Marking in the Kindergarten Population: Testing the Bimodal Distribution Hypothesis

Area of Science:

• Linguistics
• Developmental Psychology
• Speech-Language Pathology

Background:

• Previous research indicated a bimodal distribution of tense marking in clinically referred children.
• The existence of this bimodal distribution in a general population sample of young children remained unexplored.
• Tense marking is a crucial aspect of grammatical development in early childhood.

Purpose of the Study:

• To investigate if a bimodal distribution of tense marking is present in a population-based sample of kindergarten children.
• To determine if tense marking patterns in a general population align with findings from clinical samples.
• To assess the potential of tense marking as a clinical marker for language disorders.

Main Methods:

• The Test of Early Grammatical Impairment (TEGI) Screening Test was administered to 153 kindergarten children in a rural Tennessee county.
• Cluster analysis (Ward's, k-means, single linkage) was employed to analyze the distribution of TEGI Screening Test scores.
• The study sample represented 73% of the district's kindergartners, ensuring a robust population-based approach.

Main Results:

• The analysis revealed a significant deviation from a normal distribution in tense marking scores.
• Cluster analyses consistently identified a two-cluster solution as the best model, indicating a bimodal distribution.
• A large effect size (d = 4.77) demonstrated a clear boundary between typical and atypical tense marking, independent of chronological age.

Conclusions:

• The findings support the presence of a bimodal distribution of tense marking in a population-based sample of kindergarteners.
• The low-performing cluster's size aligns with prevalence estimates for specific language impairment and developmental language disorder.
• Further research with well-defined samples is recommended to solidify tense marking as a reliable clinical marker for language disorders.