Target position and practice in the identification of letters in varying contexts: A word superiority effect

Abstract

A forced-choice detection paradigm controlling for postperceptual inference was used to investigate letter identification in three-position displays. Letters from a predesignated set of four targets appeared singly, in strings of noise characters, in unpronounceable nonsense strings, and in words. Subjects knew which context would occur, but did not know which of the three display positions would contain the target. Correct detection data were collected at constant exposure duration over five testing sessions. Overall identification accuracy was higher in words than in all other contexts, the first word superiority effect to be found with targets specified in advance since Reicher's (l969). This effect remained constant over sessions. An interaction between context type and target position showed enhanced accuracy for initial and terminal letters in words, but depressed accuracy at initial and terminal positions in other contexts. This was interpreted to mean that prior knowledge of context is used to alter the dynamics of perceptual analysis.In 1969, Reicher reported a word superiority effect, in which letters were more accurately identified when presented in words than when presented alone or in nonsense strings. Since then, much research has been directed toward defining the experimental conditions under which a word superiority effect can be found, and inferring from those conditions the locus of the effect in the course of information processing (e.g., Bjork

Word and nonword superiority effects in a letter detection task

“…These data replicate the Carr et al (1976) findings. The subjects performed better on words than on consonant nonwords.…”

“…One hypothesis (Massaro, 1973) states that subjects use their knowledge of orthographic redundancy to restrict the set of letter alternatives in words. In contrast, Carr et al (1976) suggest that linguistic knowledge can directly enhance the perception of letters in words. Neither hypothesis explains the pattern of word and non word superiority effects obtained in the present study.…”

“…In contrast with Experiment 1, there was a significant improvement with practice, probably because subjects in Experiment 2 were tested more extensively. Secondly, and in contrast with Carr et al (1976), the subjects responded more quickly to single target letters than to targets embedded in consonantvowel or consonant-number items. Presumably, the single-letter superiority in the present case is due to the insertion of dashes in nontarget locations (thereby reducing positional uncertainty about target location) as well as the absence of masking.…”

“…However, a follow-up study by Carr, Lehmkuhle, Kottas, Astor-Stetson, and Arnold (1976; see also Purcell, Stanovich, & Spector, 1978) casts doubt on the generality of Massaro's conclusion. As in Massaro's work, Carr et al gave subjects advance knowledge of target letters, but, in contrast with Massaro, Carr et al introduced uncertainty about the display position in which the targets would appear.…”

“…We encouraged the relatively high error rate (10070) with the expectation that, as in Carr et al (1976), errors could be used to discriminate between conditions. Using the guideline procedure, we expected reaction times to be equivalent and accuracy to vary between conditions.…”