Word learning by children with phonological delays: differentiating effects of phonotactic probability and neighborhood density

Abstract

This study examined the ability of 20 preschool children with functional phonological delays and 34 age- and vocabulary-matched typical children to learn words differing in phonotactic probability (i.e., the likelihood of occurrence of a sound sequence) and neighborhood density (i.e., the number of words that differ from a target by one phoneme). Children were exposed to nonwords paired with novel objects in a story and learning was measured by a picture naming task. Results showed that both groups created lexical representations for rare sound sequences from sparse neighborhoods. However, only children with typical development appeared to build on this initial lexical representation to create a full representation of the word (i.e., lexical-semantic connection and semantic representation). It was hypothesized that creating a lexical representation may be too resource demanding for children with phonological delays, leaving few resources available to create a lexical-semantic connection and/or a semantic representation.

Learning outcomes: The reader will be able to (1) define phonotactic probability; (2) define neighborhood density; (3) identify how these variables impact the word learning process in general; (4) identify potential areas of deficit in the word learning process for children with functional phonological delays.

Figure 1

Mean proportion of partially correct responses by children with phonological delays (PD) and children with typical development (TD) for rare sound sequences from sparse neighborhoods (open bar), rare sound sequences from dense neighborhoods (horizontal stripes), common sound sequences from sparse neighborhoods (solid bar), and common sound sequences from dense neighborhoods (vertical stripes). Error bars indicate standard errors.

Figure 2

Mean proportion of unrelated responses by children with phonological delays (PD) and children with typical development (TD) for rare sound sequences from sparse neighborhoods (open bar), rare sound sequences from dense neighborhoods (horizontal stripes), common sound sequences from sparse neighborhoods (solid bar), and common sound sequences from dense neighborhoods (vertical stripes). Error bars indicate standard errors.

Figure 3

Mean proportion of nonwords produced as unrelated substitutes at 24 exposures. The phonotactic probability (x-axis) and neighborhood density (shading of bar) of the substituted nonword are indicated.