Orthographic regularity, positional frequency, and visual processing of letter strings.

Abstract

In 4 experiments, 2 descriptions were independently varied in the construction of 6-letter nonword strings. A probabilistic description based on frequency of occurrence of letters in each position was factorially combined with a rule-governed description defined in terms of graphemic and phonological constraints. 11 college sophomores and 16 6th graders (mean grade reading level 9.5) indicated whether a predesignated target letter was present in the strings. For both groups, orthographic regularity and summed positional frequency had only a small facilitative effect on reaction time (RT). RTs to say "no" increased dramatically with increases in the number of letters in the string that were similar to the target. When the string was presented for a short duration, followed by masking stimulus and the target letter, and college students indicated whether the target was present in the test string, accuracy of performance was dependent on orthographic regularity and summed positional frequencies of the letters in the string; no effect of letter similarity was observed. When 58 college students easily discriminated high- from low-orthographic items, the large differences that were observed between the tasks could be accounted for in terms of stages of processing. (43 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)