Date of Award


Document Type


Degree Name

Master of Arts (MA)



First Advisor

Kenneth Roberts

Second Advisor

Joe Davis

Third Advisor

Joseph C. LaVoie


The facilitative role of linguistic input on nonlinguistic categorization is frequently explained in terms of children's attention to uniquely linguistic forms such as words. In the three experiments reported here, 15-month-old infants were familiarized to visual stimuli in the context of hearing either adult-directed speech (ADS) or child-directed speech (CDS) during visual fixations. Categorization was successful with CDS and ADS input when accumulated attention was not constrained (Experiment 1). Moreover, there were no differences in accumulated attention as a function of input type. When attention was constrained to 90 seconds (Experiments 2 and 3), ADS input disrupted categorization more for female than male subjects. This disruption is not predicted by current constraints/biases accounts and suggests that a psychologically real noun-category bias may not be present prior to the vocabulary explosion.

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