Serial and parallel processes in eye movement control: current controversies and future directions.

In this editorial for the special issue on serial and parallel processing in reading we explore the background to the current debate concerning whether the word recognition processes in reading are strictly serial-sequential or take place in an overlapping parallel fashion. We consider the history of the controversy and some of the underlying assumptions, together with an analysis of the types of evidence and arguments that have been adduced to both sides of the debate, concluding that both accounts necessarily presuppose some weakening of, or elasticity in, the eye-mind assumption. We then consider future directions, both for reading research and for scene viewing, and wrap up the editorial with a brief overview of the following articles and their conclusions.

Frequency and predictability effects in the Dundee Corpus: an eye movement analysis.

Analyses carried out on a large corpus of eye movement data were used to comment on four contentious theoretical issues. The results provide no evidence that word frequency and word predictability have early interactive effects on inspection time. Contrary to some earlier studies, in these data there is little evidence that properties of a prior word generally spill over and influence current processing. In contrast, there is evidence that both the frequency and the predictability of a word in parafoveal vision influence foveal processing. In the case of predictability, the direction of the effect suggests that more predictable parafoveal words produce longer foveal fixations. Finally, there is evidence that information about word class modulates processing over a span greater than a single word. The results support the notion of distributed parallel processing.

The rank hypothesis and lexical decision: a reply to Adelman and Brown (2008).

J. S. Adelman and G. D. A. Brown (2008) provided an extensive analysis of the form of word frequency and contextual diversity effects on lexical decision time. In this reply, the current authors suggest that their analysis provides a valuable tool for the evaluation of models of lexical access and that the results they report are broadly supportive of the rank hypothesis suggested by W. S. Murray and K. I. Forster (2004)--more supportive, in fact, than the originally reported data. However, Adelman and Brown's conclusion that the results of these analyses can be taken as evidence against rank (and thereby serial models of lexical access) and for instance models is rejected. It is shown that at least one instance model makes the wrong predictions and that Adelman and Brown's conclusions rest on the assumption that lexical decision time presents a pure measure of the time involved in lexical access. Results from eye tracking are reported, which also support a rank account, as do results from analyses that show that a log frequency account is clearly inadequate. Finally, it is demonstrated that, unlike other models, the rank account continues to make accurate predictions regarding the form of both reaction time and error rate effects.

The nature and time course of pragmatic plausibility effects.

The experiments reported in this article used a delayed same/different sentence matching task with concurrent measurement of eye movements to investigate the nature of the plausibility effect. The results clearly show that plausibility effects are not due to low level lexical associative processes, but arise as a consequence of the processing of the earliest or most basic form of sentential meaning. In fact, when sentential implausibility and lexical association are varied simultaneously, it is only sentential implausibility that exerts an effect. Effects of implausibility occur rapidly--sometimes parafoveally--and are localised in the regions of the sentence where the implausibility occurs, suggesting an incremental interpretive process progressing on a roughly word-by-word basis. It is suggested that plausibility effects result from the operation of a heuristically-driven process of sentential interpretation. This appears to behave in a 'modular' fashion, despite being influenced by real world knowledge and probabilities.