Speech perception, lexicality, and reading skill.

This study examined the interaction between speech perception and lexical information among a group of 7-year-old children, of which 26 were poor readers and 36 were good readers. The children's performance was examined on tasks assessing reading skill, phonological awareness, pseudoword repetition, and phoneme identification. Although good readers showed clearly defined categorical perception in the phoneme identification task for both the /bif/-/pif/ and the /bis/-/pis/ continua, the category boundary for /bif/-/pif/ was at longer VOTs than the boundary for /bis/-/pis/, which characterizes the classic lexicality effect. Poor readers showed less sharply defined categorical perception on both continua. Although poor readers did not show the classic lexicality effect, lexicality did affect the overall rate with which phonemes were identified as /b/ or /p/ at each VOT. These findings suggest that the lexicon may operate as a compensatory mechanism for resolving ambiguities in speech perception. Furthermore, statistical correction for group differences in phoneme identification made group differences in phoneme deletion disappear, suggesting that deficits in speech perception may play a causal role in the phonological core deficit associated with reading failure.

Working memory, inhibitory control, and reading disability.

The relationships among working memory, inhibitory control, and reading skills were studied in 966 individuals, 6-49 years old. In addition to a standardized measure of word recognition, they received a working memory (listening span) task in the standard, blocked format (three sets containing two-, three-, or four-item trials) or in a mixed format (three sets each containing two-, three-, and four-item trials) to determine whether scores derived from the standard format are influenced by proactive interference. Intrusion errors were investigated in order to determine whether deficits in working memory were associated with the access, deletion, or restraint functions of inhibitory control. The results indicated that deficits in working memory were characteristic of individuals with reading disabilities at all ages. These deficits may be associated with the access and restraint functions of inhibition. Working memory skills increased until the age of 19. The blocked format showed a gradual decline in adulthood whereas the mixed format did not. The different patterns suggest that the decline in working memory skills associated with aging may result from growing inefficiencies in inhibitory control, and not diminished capacity.

Phrasing influences the recognition of melodies.

One critical step in the processing of complex auditory information (i.e., language and music) involves organizing such information into hierarchical units, such as phrases. In this study, musically trained and untrained listeners' recognition memory for short, naturalistic melodies varying in their phrase structure was tested. For musically trained subjects, memory for information preceding a phrase boundary was disrupted and memory for information subsequent to a phrase boundary was enhanced relative to memory in similar temporal locations for excerpts not containing a phrase boundary. Musically untrained listeners, in contrast, showed no such differences as a function of the phrasing of the melody. These findings conform with previous results in both psycholinguistics and musical cognition and suggest that the phrase serves as a functional unit in musical processing, guiding the parsing of musical sequences during perception, along with the structuring of memory for musical passages.

Semantic priming in visual word recognition: Activation blocking and domains of processing.

The fact that letter search on a prime eliminates the typically robust semantic priming effect in lexical decision is often attributed to the "shallowness" of the prime-processing task. In three experiments we investigated this claim by using two different "shallow" prime-processing tasks: letter search and color identification. Consistent with previous reports, lexical decisions to semantically related targets were not facilitated when subjects searched the prime for a probe letter. In contrast, semantic priming was observed following a color discrimination task on the prime. We suggest that a levels-of-processing interpretation is not an adequate framework for understanding these data. Instead, a domain-specific processing account is offered in which explicit processing at the letter level (as in letter search) makes demands on resources (e.g., activation) that drives processing at the semantic level. This competition is resolved by establishing a temporary activation block at the lexical-semantic interface, which results in the elimination or attenuation of semantic priming. In contrast, global judgment of color is viewed as a domain that does not make demands on the resources that drive the visual word recognition machinery. There is therefore no need for an activation block, and semantic priming is not prevented.