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Eye-movement control during reading depends on foveal and parafoveal information. If the parafoveal preview of the next word is suppressed, reading is less efficient. A linear mixed model (LMM) reanalysis of McDonald (2006) confirmed his observation that preview benefit may be limited to parafoveal words that have been selected as the saccade target. Going beyond the original analyses, in the same LMM, we examined how the preview effect (i.e., the difference in single-fixation duration, SFD, between random-letter and identical preview) depends on the gaze duration on the pretarget word and on the amplitude of the saccade moving the eye onto the target word. There were two key results: (a) The shorter the saccade amplitude (i.e., the larger preview space), the shorter a subsequent SFD with an identical preview; this association was not observed with a random-letter preview. (b) However, the longer the gaze duration on the pretarget word, the longer the subsequent SFD on the target, with the difference between random-letter string and identical previews increasing with preview time. A third pattern-increasing cost of a random-letter string in the parafovea associated with shorter saccade amplitudes-was observed for target gaze durations. Thus, LMMs revealed that preview effects, which are typically summarized under "preview benefit", are a complex mixture of preview cost and preview benefit and vary with preview space and preview time. The consequence for reading is that parafoveal preview may not only facilitate, but also interfere with lexical access.

We asked whether people process words during saccades when reading sentences. Irwin (1998) demonstrated that such processing occurs when words are presented in isolation. In our experiment, participants read part of a sentence ending in a high- or low-frequency target word and then made a long (40 degrees) or short (10 degrees) saccade to the rest of the sentence. We found a frequency effect on the target word and the first word after the saccade, but the effect was greater for short than for long saccades. Readers therefore performed more lexical processing during long saccades than during short ones. Hence, lexical processing takes place during saccades in text comprehension.

When saccades are evoked by suddenly presented visual stimuli, the stochastic distribution of their reaction times is typically recinormal, in conformity with the LATER model of decision-making, sometimes with an additional sub-population of early responses. In the real world, saccades are more often spontaneous responses to static features of the visual world; nevertheless, the time between the end of one saccade and the start of the next may be regarded as a reaction time to the new image that is presented to the retina. The distribution of these times is qualitatively similar to that of evoked saccades, but typically with a longer median and more of the early responses. Here, we analyse the statistical distributions of fixation times from a large database of spontaneous saccades made while reading and show that the distributions are altered in characteristic ways by particular features of the current fixation: likely familiarity of the currently fixated word, and its proximity to the preceding fixation. These alterations are of the kind predicted by LATER: familiarity appears to influence the mean rate at which the decision signal approaches completion, whereas proximity to the previous fixation, presumably because it provides partial prior information about the upcoming word, appears to increase prior probability. We conclude that spontaneous saccades may be successfully described by the same decision-making model that can be used for evoked ones.

Previous research has demonstrated that reading is less efficient when parafoveal visual information about upcoming words is invalid or unavailable; the benefit from a valid preview is realised as reduced reading times on the subsequently foveated word, and has been explained with reference to the allocation of attentional resources to parafoveal word(s). This paper presents eyetracking evidence that preview benefit is obtained only for words that are selected as the saccade target. Using a gaze-contingent display change paradigm (Rayner, K. (1975). The perceptual span and peripheral cues in reading. Cognitive Psychology, 7, 65-81), the position of the triggering boundary was set near the middle of the pretarget word. When a refixation saccade took the eye across the boundary in the pretarget word, there was no reliable effect of the validity of the target word preview. However, when the triggering boundary was positioned just after the pretarget word, a robust preview benefit was observed, replicating previous research. The current results complement findings from studies of basic visual function, suggesting that for the case of preview benefit in reading, attentional and oculomotor processes are obligatorily coupled.

Patients with an acquired homonymous hemianopia often adapt over a period of a few months to compensate for some of the impairments caused by their visual field defect. Changes in their eye movement patterns have been demonstrated as performance on visual tasks improves with time; however, these patients often complain of persistent text reading problems. Using a video-based eye-movement tracking system, we investigated the text reading behaviour of patients with established hemianopic alexia (>6 months post deficit), a condition affecting left-to-right readers, with a homonymous field defect that encroaches into their right foveal/parafoveal visual field. Word-based analyses of text reading are standard in experiments involving normal readers, but this is the first time these methods have been extended to patients with hemianopic alexia. Using this method, we compared the patients' reading scanpaths to those generated by normal controls reading the same passages, and a random model generated by matching the patients' eye movement data to random permutations of the text they read. We demonstrate that patients adopt an inefficient reading strategy, fixating to the left of the preferred viewing location of words of four letters and longer. Fixating to the left of the normal preferred viewing location not only results in less of the fixated word being processed by the language system; ensuing fixations are also more likely to land within the same word (a refixation). It is this refixation rate that is the main factor in slowing reading times in these patients. Our data suggests that patients are able to extract some useful visual information from text to aid the planning of reading scanpaths as their behaviour differs critically from the random model. Potential reasons for this patient group failing to produce an effective reading strategy are discussed.

This article presents SERIF, a new model of eye movement control in reading that integrates an established stochastic model of saccade latencies (LATER; R. H. S. Carpenter, 1981) with a fundamental anatomical constraint on reading: the vertically split fovea and the initial projection of information in either visual field to the contralateral hemisphere. The novel features of the model are its simulation of saccade latencies as a race between two stochastic rise-to-threshold LATER units and its probabilistic selection of the target for the next saccade. The model generates simulated eye movement behavior that exhibits important characteristics of actual eye movements made during reading; specifically, simulations produce realistic saccade target distributions and replicate a number of critical reading phenomena, including the effects of word frequency on fixation durations, the inverted optimal viewing position effect, the trade-off between first and second fixation durations of refixated words, and the dependence of parafoveal preview benefit on eccentricity., (Copyright (c) 2005 APA, all rights reserved.)

In empirical studies of human eye movement behavior during reading, it is common to compute various summary measures from the data, but these measures are typically not evaluated with respect to corresponding measures of baseline performance. The authors present a method for deriving an appropriate baseline by mapping the actual behavior to a random perturbation of the text being read, and they find surprising similarities between the baseline and the empirical data. The practical message from these findings is that the importance of a particular factor in explaining either empirical or simulated eye movement patterns should be evaluated using an appropriate baseline. In addition to this methodological point, the authors suggest that eye movement behavior in reading may be constrained by the properties of an eye-guidance system that has adapted to the coarse-grained statistical properties of written language., (((c) 2005 APA, all rights reserved).)

Two empirical predictions can be generated from recent parallel processing models of eye movement control in reading concerning the phenomenon of parafoveal preview benefit. These predictions derive from the assumption that lexical activation accumulates across more than one saccade. A large corpus of eye movement data was used to determine whether parafoveal preview benefit of a target word is modulated by (1) its distance from the penultimate fixation, and (2) the amount of time it spends in the 'perceptual span'. There was an unexpected inverse relationship between first fixation duration and distance: fixations were longer the closer the penultimate fixation was to the target word, and a positive relationship between fixation duration and time: fixations were longer the greater the summed durations of the ultimate and penultimate fixations. These findings represent a challenge for computational models of eye movements in reading.

The human fovea and visual pathways are precisely split: information in one hemifield is initially projected to the contralateral visual cortex. This fundamental anatomical constraint on word recognition in reading has been largely ignored in eye movement research. We explore the consequences of this constraint through analyses of a large corpus of eye movement data, and demonstrate that aspects of saccade planning (target selection, initial landing position) are sensitive to both hemispheres, estimated uncertainty about the identity of the currently fixated word. We interpret these findings in terms of a hemispheric division of labour. We suggest that anatomical, visual and lexical factors all contribute to the decision of where to send the eyes next in reading.

We argue that the vertical division of the fovea and the hemispheric division of the brain condition reading, and that hemispheric desynchronization is a proximal cause of dyslexia. We predict that dyslexics' fixation behaviour in reading accommodates to problematic hemispheric transfer/coordination, with fixations projecting more letter-information directly to the left hemisphere to facilitate processing. We analysed eye movements of 24 dyslexics and 24 normal readers. Dyslexics fixated closer to word beginning than did normal readers, projecting more of the word directly to the left hemisphere. Both groups produced comparable fixation durations at the beginning of the word; further into the word the dyslexics produced longer fixation durations. The results support a model of dyslexia based on hemispheric desynchronization.

Skilled readers are able to derive meaning from a stream of visual input with remarkable efficiency. In this article, we present the first evidence that statistical information latent in the linguistic environment can contribute to an account of reading behavior. In two eye-tracking studies, we demonstrate that the transitional probabilities between words have a measurable influence on fixation durations, and using a simple Bayesian statistical model, we show that lexical probabilities derived by combining transitional probability with the prior probability of a word's occurrence provide the most parsimonious account of the eye movement data. We suggest that the brain is able to draw upon statistical information in order to rapidly estimate the lexical probabilities of upcoming words: a computationally inexpensive mechanism that may underlie proficient reading.

We report the results of an investigation into the ability of transitional probability (word-to-word contingency statistics) to account for reading behaviour. Using a corpus of eye movements recorded during the reading of newspaper text, we demonstrate both the forward [P(n/n-1)] and backward [P(n/n+1)] transitional probability measures to be predictive of first fixation and gaze durations: the higher the transitional probability, the shorter the fixation time. Initial fixation position was also affected by the forward measure; we observed a small rightward shift for words that were highly predictable from the preceding word. Although transitional probability is sensitive to word class, with function words being generally more predictable from their context than content words, the measures accounted equally well for the data for both classes.

Sentence completion norms are a valuable resource for researchers interested in studying the effects of context on word recognition processes. Norms for 112 Spanish sentences were compiled with the use of experimental software accessed over the World-Wide Web. Several measures summarizing the distribution of responses for each sentence are reported, including Schwanenflugel's (1986) multiple-production measure of sentence constraint strength, the type-token ratio, and the information-theoretic measure of redundancy. The complete set of completion norms is available at http://www.ling.ed.ac.uk/~monica/spanish_completion_norms.html.

We explore two aspects of exovergence: we test whether smaller binocular fixation disparities accompany the shorter saccades and longer fixations observed in reading Chinese, and we test whether potentially advantageous psychophysical effects of exovergence transfer to text reading. We report differential exovergence in reading Chinese and English: Chinese readers begin fixations with more binocular disparity, but end fixations with a disparity closely similar to that of the English readers. We conclude that greater fixation-initial binocular disparity can be adaptive in the reading of visually and cognitively denser text. [ABSTRACT FROM AUTHOR]

Word length is an important determinant of eye movement behaviour in reading. The current study is the first attempt to disconfound a word's number of letters from its spatial extent. In a sentence-reading experiment using closely matched stimuli, clear differences were observed between target words that subtended the same visual angle but differed in number of letters: the more letters in the word, the more fixations made on the word, and the longer the duration of these fixations. Analyses of the full set of sentence words confirmed these results for a wider range of word lengths, and are consistent with a role for number-of-letters distinct from spatial extent. The most plausible explanation for these findings is that long words are subject to a greater degree of visual crowding, which is costly for both temporal and spatial eye movement systems. [ABSTRACT FROM AUTHOR]

Recent research has suggested that refixation saccades in reading can be planned before the first fixation is made on a word. If some proportion of refixations are preplanned, then the asymmetric shape of initial landing position distributions may be due to the mixing of two populations of saccades—planned single-fixations that are aimed at word-centre and planned refixation sequences that are aimed near word-beginning. Here, we used Monte-Carlo methods in conjunction with a computational model of saccade planning to estimate the proportion of preplanned refixations in normal reading. Simulation results suggest that about 20% of refixation saccades were preplanned and that preplanning was associated with an initial landing position nearer word-beginning for multiple-fixation cases compared with single-fixation cases. [ABSTRACT FROM AUTHOR]

We argue that the reading of words and text is fundamentally conditioned by the splitting of the fovea and the hemispheric division of the brain, and, furthermore, that the equitable division of labour between the hemispheres is a characteristic of normal visual word recognition. We report analyses of a representative corpus of the eye fixations of normal readers in the realistic reading of text where we compare hemispheric processing, quantified in terms of uncertainty about the orthographic, phonological and semantic representations of the words of the text. The analyses show that normal reading is accurately understood in terms of an equitable division of labour in the construction of the orthographic identity of the word and that, for English, a semantic division patterns closely with the orthographic division. We infer that impaired inter-hemispheric co-ordination of orthographic information may be best compensated for by a reliance on the inter-hemispheric co-ordination of semantic information, as in phonological dyslexia. [ABSTRACT FROM AUTHOR]

We argue that models of reading should be based on anatomical reality, namely, the fact that both eyes are used in reading; and the observation that the human fovea is precisely vertically split, and projects each half of a fixated word to the contralateral hemisphere. [ABSTRACT FROM AUTHOR]