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Purpose: This study explored the effect of frequency (number of presentations), and spacing (period between presentations) on verb learning in children with specific language impairment (SLI). Children learn words more efficiently when presentations are frequent and appropriately spaced, and this study investigated whether children with SLI likewise benefit. Given that these children demonstrate greater frequency dependence and rapid forgetting of recently acquired words, an investigation of frequency and spacing in this population is especially warranted.
Method: Twenty-four children with SLI (mean age 5;6 [years;months]) and 24 language-matched control children (mean age 3;4) were taught novel verbs during play sessions. In a repeated measures design, 4 experimental conditions combined frequency (12 or 18 presentations) and spacing (all presentations in 1 session, or spread over 4 days). Comprehension and production probes were administered after the final session and 1 week later.
Results: Although the children with SLI benefited significantly from frequent and widely spaced presentations, there were no significant effect in the control group. The language-impaired children showed rapid forgetting.
Conclusions: The frequency and spacing of presentations crucially affect the verb learning of children with SLI. A training regimen characterized by appropriately spaced intervals and moderate repetition will optimally benefit lexical learning.
KEY WORDS: verb learning, specific language impairment, frequency effects, spacing effects
Comparatively few word learning studies have investigated the effect of frequency and spacing (i.e., the number of presentations and the intervals between them). The dearth of studies in this area is surprising given that recent research has demonstrated that spacing and frequency crucially affect word learning performance. Moreover, one particular group of children-those with specific language impairment (SLI)-may be particularly sensitive to the effect of frequency and spacing. This study aimed to investigate the influence of these two factors on the word learning of these children.
Frequency
Many researchers have argued that word learning is an automatic process characterized by extremely rapid learning. The term fast-mapping (Carey & Bartlett, 1978) has been used to describe how young children learn new words after a minimal number of exposures, or perhaps after even one exposure. In addition to being quickly learned, fast-mapped words are also retained for long periods of time (e.g., Carey & Bartlett, 1978; Markson & Bloom, 1997; Woodward, Markman, & Fitzsimmons, 1994).