Development of adult-like performance in backward, simultaneous, and forward masking

Some researchers have argued that specific language impairment (SLI) is associated with deficits in processing certain temporal aspects of auditory stimuli. One recent study (Wright et al., 1997) suggests that backward masking in particular poses a problem for children with SLI, as compared to simultaneous or forward masking. Interpretation of this finding is complicated by the fact that very little is known about the development of normal, adult-like performance in these masking paradigms. The study reported here examined performance for children 5-11 years old on forward, simultaneous, and backward masking and compared their performance to that of adults. The data show a trend for improvement in performance with age in all three masking paradigms. There was no evidence for later or more gradual improvement in performance on the backward-masking paradigm. However, backward-masking thresholds were more variable than those in the other conditions and were subject to greater individual differences, even in the adult data set. Manipulation of masker bandwidth yielded no evidence for more adult-like performance in the child data with the wider bandwidth masker. Additional data collected on two naive adult observers show a marked improvement in backward-masking performance over rime, suggesting that detection with these stimuli might be particularly subject to practice effects.