Word list reading fluency is theoretically expected to depend mainly on single word reading speed. Yet the correlation between the two diminishes with increasing fluency, while fluency remains strongly correlated to serial digit naming. This suggests that multi-element sequence processing is an important component of fluency. When multiple stimuli to be named are presented simultaneously, the total naming time is shorter than when they are presented individually (termed “serial advantage”). Presumably, this occurs because one or more stimuli can be processed simultaneously, for example by one stimulus being mapped to its phonological representation while the previous one is articulated and the next one is visually perceived. This temporal overlap, termed “cascaded” processing, amounts to the parallel processing of multiple sequential stimuli along a serial pipeline.

Dr. Protopapas will present data from serial and discrete naming and reading tasks in different orthographies supporting the hypotheses that (a) these tasks pattern along distinct dimensions of performance concerning sequential vs. single-entity processing; (b) stimuli are amenable to cascaded processing to the extent they are individually processed as unmediated single chunks; and (c) the serial advantage is limited by the slowest processing component. The first hypothesis suggests that a distinct skill domain, beyond single word processing, underlies efficient processing of word sequences (i.e., fluency). The second hypothesis distinguishes between alphanumeric and nonalphanumeric naming and sets the context for the study of word reading fluency development. The third hypothesis suggests that as long as articulation is faster than the preceding cognitive steps then the serial advantage is largely determined by the duration of the spoken words, but articulation goes on to become the rate-limiting factor as word recognition speeds up during reading development.

Serial word reading aligns increasingly with the serial naming factor at higher grades, suggesting that word reading fluency is gradually dominated by skill in simultaneously processing multiple successive items (“cascading”), beyond automatization of individual words. This explains why discrete word reading is decreasingly correlated with word reading fluency as reading skill increases and why serial digit naming (i.e., RAN) is such a strong concurrent and longitudinal predictor of word reading fluency.