| Abstract: | Although there is evidence that selective adaptation and contrast effects in speech perception are produced by the same mechanisms, J. R. Sawusch and P. Jusczyk (see record 1982-00351-001) reported a dissociation between the effects and concluded that adaptation and contrast occur at separate processing levels. They found that an ambiguous test stimulus was more likely to be labeled b following adaptation with pha] and more likely to be labeled p following adaptation with ba] or spa], the latter consisting of ba] preceded by s] noise. In the contrast session, where a single context stimulus occurred with a single test item, the ba] and pha] contexts had contrastive effects similar to those of the ba] and pha] adaptors, but the spa] context produced an increase in b responses to the test stimulus, an effect opposite to that of the spa] adaptor. One interpretation of this difference is that the rapid presentation of the spa] adaptor gave rise to streaming, whereby the s] was perceptually segregated from the ba]. The present experiment, with 37 undergraduates, essentially replicated the results of Sawusch and Jusczyk, using procedures similar to theirs. An increase in the interadaptor interval to remove the likelihood of stream segregation produced a convergence between the adaptation and contrast effects. It is concluded that the relationship between the feature-detection hypothesis and adaptation results remains highly equivocal. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
