Better the DVL you know: acronyms reveal the contribution of familiarity to single-word reading

Abstract

Current theories of reading are divided between dual-route accounts, which propose that separable processes subserve word recognition for orthographically regular and irregular strings, and connectionist models, which propose a single mechanism mapping form to meaning. These theories make distinct predictions about the processing of acronyms, which can be orthographically illegal and yet familiar, as compared with the processing of pseudowords, which are regular but unfamiliar. This study examined whether acronyms are processed like pseudowords and words. Event-related potentials (ERPs) were recorded as subjects viewed familiar and unfamiliar acronyms, words, pseudowords, illegal strings, and--as the targets of the substantive behavioral task--proper names. Familiar acronyms elicited repetition effects on the N400 component, a functionally specific index of semantic activation processes; repetition effects for familiar acronyms were similar in magnitude, timing, and scalp distribution to those for words and pseudowords. The similarity of the brain response to familiar--but--illegal and unfamiliar--but--legal classes of stimuli is inconsistent with predictions of dual-route models of reading.

Fig. 1

Grand-average difference waves (first minus second presentation) for familiar acronyms, words, pseudowords, and illegal strings at the middle parietal channel (with an example from each stimulus category indicated above the category name).

Fig. 2

Mean amplitude of the 250- to 450-ms epoch of repetition-effect difference waves, averaged over central parietal channels. Results are shown separately for words, pseudowords, familiar acronyms, unfamiliar acronyms, and illegal items. Repetition effects larger than zero at a confidence level of .05 are indicated by an asterisk. Error bars represent the standard errors of the means.

Fig. 3

Familiar-acronym repetition effect. Grand-average repetition-effect difference waves for familiar acronyms at all 26 scalp channels are displayed in (a), with the middle parietal waveform circled. The distribution of the effect (top view of the head) between 325 and 375 ms after stimulus onset is shown in (b).