Constraints on integration of orthographic information across multiple stimuli: effects of contiguity, eccentricity, and attentional span.

Five flanked lexical decision experiments investigated the integration of information across spatially distinct letter strings. Experiment 1 found no significant difference between quadrigram flankers (e.g., CKRO ROCK CKRO) and double bigram flankers (e.g., CK RO ROCK CK RO). Experiment 2 varied the eccentricity of single bigram flankers and found that closer flankers generated greater effects. A combined analysis of these experiments revealed that the double bigram condition (Experiment 1) was less effective than the close single bigram condition (Experiment 2). Experiment 3 tested one explanation for this pattern - that the outer bigrams in the double bigram condition interfered with processing the inner bigrams, and that spatial integration only operates across adjacent stimuli. In Experiment 3, outer bigrams were now a repeat of the inner bigram (e.g., RO RO ROCK CK CK), and this repeated bigram condition was still found to be significantly less effective than single bigrams. Experiments 4 and 5 tested an alternative explanation whereby the addition of spatially distinct flanking stimuli increases the spread of spatial attention, hence reducing the impact of proximal flankers. In line with this explanation, we found no significant difference between repeated bigram flankers and a condition where only the inner bigram was related to the target (e.g., CA RO ROCK CK SH). We conclude that spatial integration processes only operate across the central target and proximal flankers, and that these effects are diluted by the increased spread of spatial attention caused by additional spatially distinct flankers.

A developmental perspective on morphological processing in the flankers task.

Recent research with adult participants using the flankers task has shown that the recognition of central target words is facilitated by the presence of morphologically related flanker words. Here we explored the development of such morphological flanker effects in two groups of primary school children (average ages = 8 years 6 months and 10 years 3 months) and a group of adult participants. We examined effects of a transparent morphological relation in two conditions: one where the target was the stem and flankers were derivations (e.g., farmer farm farmer) and the other where the flankers were stems and the target was the derived form (e.g., farm farmer farm). Morphological flanker effects were compared with repetition flanker effects with the same set of stimuli (e.g., farm farm farm; farmer farmer farmer), and effects of related flankers were contrasted with the appropriate unrelated flankers. Results revealed no significant effect of morphological relatedness in the two groups of children and a significant effect in the adult group, but only for suffixed targets and stem flankers. Repetition effects for stem targets were found across all groups, whereas repetition effects for suffixed targets were found only in the older children and adults. These results show that morphological processing, in a context involving multiple words presented simultaneously, takes several years to develop and that morphological complexity (stem vs. derived) is a limiting factor for repetition effects in the flankers task with young children.

Attention extends beyond single words in beginning readers.

A common notion is that during the first stages of learning to read, attention is narrowly focused so as to encompass only a single or a few letters. In skilled adult readers, however, attention extends beyond single words. The latter is evidenced by faster recognition of words that have many letters in common with surrounding words, along with correlations between such integration effects and measures of attention. These premises suggest that the distribution of attention gradually increases as a function of reading skill, and that this progression can be mapped by measuring spatial integration effects across the course of reading development. The latter was undertaken in the present study, in which we employed the flanker paradigm combined with the lexical decision task. Children in grades 1-6 (N = 113) were shown central target words flanked by various types of orthographically related and unrelated flanking stimuli. Against expectations, significant effects of flanker relatedness on word recognition speed were found in the youngest children, and this effect was not modulated by reading age. Our results challenge the notion that attention is focused on single letters in beginning readers, and instead suggest that, from the earliest stages of reading development, orthographic processing can extend beyond single words.

Orthographic and phonological contributions to flanker effects.

Does phonology contribute to effects of orthographically related flankers in the flankers task? In order to answer this question, we implemented the flanker equivalent of a pseudohomophone priming manipulation that has been widely used to demonstrate automatic phonological processing during visual word recognition. In Experiment 1, central target words were flanked on each side by either a pseudohomophone of the target (e.g., roze rose roze), an orthographic control pseudoword (rone rose rone), or an unrelated pseudoword (mirt rose mirt). Both the pseudohomophone and the orthographic control conditions produced faster and more accurate responses to central targets, but performance in these two conditions did not differ significantly. Experiment 2 tested the same stimuli in a masked priming paradigm and replicated the standard finding in French that pseudohomophone primes produce significantly faster responses to target words than orthographic control primes. Therefore, contrary to its impact on masked priming, phonology does not contribute to effects of flanker relatedness, which would appear to be driven primarily by orthographic overlap.