Spatial attention modulates feature crosstalk in visual word processing

One major idea about spatial attention is that it serves to modulate crosstalk between features during reading. Two reading aloud experiments are reported in which a cue-validity manipulation was combined with manipulations that are thought to increase the likelihood of feature-level crosstalk: interletter spacing and the presence or absence of irrelevant features. Both experiments yielded an interaction between the effects of spatial cuing and each of these factors. These results are taken to support the hypothesis that when spatial attention is focused on the word, it provides protection against crosstalk among features in the context of reading aloud.     

A paradigm for exploring what the mind does while deciding what it should do.

One widespread belief about automatic mental processes is that, among other characteristics, they are involuntary. No initial conscious intent is necessary because such processing is stimulus initiated. This claim was studied in the context of a novel task-choice procedure in which subjects were informed as to which of two tasks they should perform on a letter string either well in advance of a target, or when the target appeared. The hypothesis that initial processing of the target occurs without intent predicts that the effect of contrast reduction will be absent when the task cue appears synchronously with the target. This is because initial processing of the target should be completed during the time taken to decode the task cue. The results are inconsistent with this account. Instead, they support an account in which functional target processing is delayed until the subject knows what the task is. Some directions for future investigations are noted.     

Dissociative effects of stimulus quality on semantic and morphological contexts in visual word recognition.

Semantic and morphological contexts were manipulated jointly with stimulus quality under conditions where there were few related prime-target pairs (i.e., low relatedness proportion) in a lexical decision experiment. Additive effects of semantic context and stimulus quality on RT were observed, replicating previous work. In contrast, morphological context interacted with stimulus quality. This dissociation is discussed in the context of Besner and colleagues' evolving multistage framework. The essence of the account is that 1) stimulus quality affects feature and letter levels, but not later levels, 2) feedback from semantics to the lexical level is inoperative under low relatedness proportion conditions (hence stimulus quality and semantic context yield additive effects), whereas 3) feedback from the lexical level to the letter level is intact, hence stimulus quality and morphological context produce an interaction by virtue of them affecting a common stage of processing.     

Neighbourhood density effects in reading aloud: new insights from simulations with the DRC model.

A series of nine simulations with the Dual Route Cascaded (DRC) model (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001) investigated neighbourhood density (N) effects in nonword and word naming. Two main finding emerged from this work. First, when naming nonwords there are two loci for the effect of N in the model, contrary to Coltheart et al.'s single locus explanation of what the model is doing. The early N effect involves interactive activation between the orthographic lexicon and the letter units such that high N facilitates letter identification, which in turn affects the nonlexical route. The late N effect arises from activation in the orthographic lexicon that feeds forward to the phonological lexicon and primes phonemes in the phoneme system. Second, when naming words the presence/absence of an effect of N on the Letter Units through feedback from the lexical level depends on the parameter settings. Implications and suggestions for future directions are made.     

Spatial attention as a necessary preliminary to early processes in reading.

One major theory of the relation between spatial attention and visual word recognition holds that the former is a necessary condition for the latter to begin. A different major theory asserts that although spatial attention can facilitate the latter, it is not a necessary condition. These two theories were pitted against each other experimentally. Spatial attention was operationalized in terms of the effect of a spatial precue on the time to name a target word that appeared above or below fixation. A masked prime word was presented before the target. The critical difference between experiments was cue validity (50% in Experiments 1a and 2a and 100% in Experiments 1b and 2b). Repetition priming was observed when the prime appeared in the uncued prime location in Experiments la and 2a but not in Experiments 1b or 2b. These results are inconsistent with the claim that visual word recognition does not depend on spatial attention. Discussion centres on the distribution of spatial attention across target locations as a function of cue validity.     

Stroop dilution revisited: evidence for domain-specific, limited-capacity processing

Nine experiments show that in the context of Stroop dilution the extent to which flanking distractors are processed depends on the nature of the material at fixation. A Stroop effect is eliminated if a word or a nonword is colored and appears at fixation and the color word appears as a flanker. A Stroop effect is observed when the color carrier at fixation is from a different domain than the color word distractor (e.g., Arabic digits). It is argued that when the material at fixation is in the same domain as the color word distractor, the distractor is not processed. Taken together, these results implicate a role for material-specific, limited-capacity processing in the context of this variant of the Stroop paradigm.     

Contextual control over lexical and sublexical routines when reading English aloud

Are the processes responsible for reading aloud single well-formed letter strings under contextual control? Despite the widespread contention that the answer to this question is “yes,” it has been remarkably difficult to provide a compelling demonstration to that effect. In a speeded naming experiment, skilled readers read aloud exception words (such asPint) that are atypical in terms of their spelling sound correspondences and nonwords (such asFlad) that appeared in a predictable sequence. Subjects took longer to name both words and nonwords when the item on the preceding trial was from the other lexical category, relative to when the preceding item was from the same lexical category. This finding is consistent with the relative contributions of lexical and sublexical knowledge being controlled. We note a number of different ways that this control could arise and suggest some directions for future research.