Parafoveal processing in word recognition

Auditory distraction during reading: Investigating the effects of background sounds on parafoveal processing

Previous research suggests that unexpected (deviant) sounds negatively affect reading performance by inhibiting saccadic planning, which models of reading agree takes place simultaneous to parafoveal processing. This study examined the effect of deviant sounds on foveal and parafoveal processing. Participants read single sentences in quiet, standard (repeated sounds), or deviant sound conditions (a new sound within a repeated sound sequence). Sounds were presented with a variable delay coincident with the onset of fixations on target words during a period when saccadic programming and parafoveal processing occurred. We used the moving window paradigm to manipulate the amount of information readers could extract from the parafovea (the entire sentence or a 13-character window of text). Global, sentence-level analyses showed typical disruption to reading by the window, and under quiet conditions similar effects were observed at the target and post-target word in the local analyses. Standard and deviant sounds also produced clear distraction effects of differing magnitudes at the target and post-target words, though at both regions, these effects were qualified by interactions. Effects at the target word suggested that with sounds, readers engaged in less effective parafoveal processing than under quiet. Similar patterns of effects due to standard and deviant sounds, each with a different time course, occurred at the post-target word. We conclude that distraction via auditory deviation causes disruption to parafoveal processing during reading, with such effects being modulated by the degree to which a sound's characteristics are more or less unique.

The effects of simulated hemianopia on eye movements during text reading

Vision loss is a common, devastating complication of cerebral strokes. In some cases the complete contra-lesional visual field is affected, leading to problems with routine tasks and, notably, the ability to read. Although visual information crucial for reading is imaged on the foveal region, readers often extract useful parafoveal information from the next word or two in the text. In hemianopic field loss, parafoveal processing is compromised, shrinking the visual span and resulting in slower reading speeds. Recent approaches to rehabilitation using perceptual training have been able to demonstrate some recovery of useful visual capacity. As gains in visual sensitivity were most pronounced at the border of the scotoma, it may be possible to use training to restore some of the lost visual span for reading. As restitutive approaches often involve prolonged training sessions, it would be beneficial to know how much recovery is required to restore reading ability. To address this issue, we employed a gaze-contingent paradigm using a low-pass filter to blur one side of the text, functionally simulating a visual field defect. The degree of blurring acts as a proxy for visual function recovery that could arise from restitutive strategies, and allows us to evaluate and quantify the degree of visual recovery required to support normal reading fluency in patients. Because reading ability changes with age, we recruited a group of younger participants, and another with older participants who are closer in age to risk groups for ischaemic strokes. Our results show that changes in patterns of eye movement observed in hemianopic loss can be captured using this simulated reading environment. This opens up the possibility of using participants with normal visual function to help identify the most promising strategies for ameliorating hemianopic loss, before translation to patient groups.

Attentional and meta-cognitive processes underlying mind wandering episodes during continuous naturalistic reading are associated with specific changes in eye behavior

Although eye movements during reading have been studied extensively, their variation due to attentional fluctuations such as spontaneous distractions is not well understood. Here we used a naturalistic reading task combined with an attentional sampling method to examine the effects of mind wandering-and the subsequent metacognitive awareness of its occurrence-on eye movements and pupillary dynamics. Our goal was to better understand the attentional and metacognitive processes involved in the initiation and termination of mind wandering episodes. Our results show that changes in eye behavior are consistent with underlying independent cognitive mechanisms working in tandem to sustain the attentional resources required for focused reading. In addition to changes in blink frequency, blink duration, and the number of saccades, variations in eye movements during unaware distractions point to a loss of the perceptual asymmetry that is usually observed in attentive, left-to-right reading. Also, before self-detected distractions, we observed a specific increase in pupillary diameter, indicating the likely presence of an anticipatory autonomic process that could contribute to becoming aware of the current attentional state. These findings stress the need for further research tackling the temporal structure of attentional dynamics during tasks that have a significant real-world impact.

Incremental Language Comprehension Difficulty Predicts Activity in the Language Network but Not the Multiple Demand Network

What role do domain-general executive functions play in human language comprehension? To address this question, we examine the relationship between behavioral measures of comprehension and neural activity in the domain-general "multiple demand" (MD) network, which has been linked to constructs like attention, working memory, inhibitory control, and selection, and implicated in diverse goal-directed behaviors. Specifically, functional magnetic resonance imaging data collected during naturalistic story listening are compared with theory-neutral measures of online comprehension difficulty and incremental processing load (reading times and eye-fixation durations). Critically, to ensure that variance in these measures is driven by features of the linguistic stimulus rather than reflecting participant- or trial-level variability, the neuroimaging and behavioral datasets were collected in nonoverlapping samples. We find no behavioral-neural link in functionally localized MD regions; instead, this link is found in the domain-specific, fronto-temporal "core language network," in both left-hemispheric areas and their right hemispheric homotopic areas. These results argue against strong involvement of domain-general executive circuits in language comprehension.

Incremental Language Comprehension Difficulty Predicts Activity in the Language Network but Not the Multiple Demand Network

What role do domain-general executive functions play in human language comprehension? To address this question, we examine the relationship between behavioral measures of comprehension and neural activity in the domain-general "multiple demand" (MD) network, which has been linked to constructs like attention, working memory, inhibitory control, and selection, and implicated in diverse goal-directed behaviors. Specifically, functional magnetic resonance imaging data collected during naturalistic story listening are compared with theory-neutral measures of online comprehension difficulty and incremental processing load (reading times and eye-fixation durations). Critically, to ensure that variance in these measures is driven by features of the linguistic stimulus rather than reflecting participant- or trial-level variability, the neuroimaging and behavioral datasets were collected in nonoverlapping samples. We find no behavioral-neural link in functionally localized MD regions; instead, this link is found in the domain-specific, fronto-temporal "core language network," in both left-hemispheric areas and their right hemispheric homotopic areas. These results argue against strong involvement of domain-general executive circuits in language comprehension.

The Role of Attention in Word Recognition: Results from OB1-Reader

When reading, orthographic information is extracted not only from the word the reader is looking at, but also from adjacent words in the parafovea. Here we examined, using the recently introduced OB1‐reader computational model, how orthographic information can be processed in parallel across multiple words and how orthographic information can be integrated across time and space. Although OB1‐reader is a model of text reading, here we used it to simulate single‐word recognition experiments in which parallel processing has been shown to play a role by manipulating the surrounding context in flanker and priming paradigms. In flanker paradigms, observers recognize a central word flanked by other letter strings located left and right of the target and separated from the target by a space. The model successfully accounts for the finding that such flankers can aid word recognition when they contain bigrams of the target word, independent of where those flankers are in the visual field. In priming experiments, in which the target word is preceded by a masked prime, the model accounts for the finding that priming occurs independent of whether the prime and target word are in the same location or not. Crucial to these successes is the key role that spatial attention plays within OB1‐reader, as it allows the model to receive visual input from multiple locations in parallel, while limiting the kinds of errors that can potentially occur under such spatial pooling of orthographic information.

The dynamic adjustment of saccades during Chinese reading: Evidence from eye movements and simulations

This article reports an eye-movement experiment in which participants scanned continuous sequences of Landolt-Cs for target circles to examine the visual and oculomotor constraints that might jointly determine where the eyes move in a task that engages many of the perceptual and motor processes involved in Chinese reading but without lexical or linguistic processing. The lengths of the saccades entering the Landolt-C clusters were modulated by the processing difficulty (i.e., gap sizes) of those clusters. Simulations using implemented versions of default-targeting (Yan, Kliegl, Richter, Nuthmann, & Shu, 2010) versus dynamic-adjustment (Liu, Reichle, & Li, 2016) models of saccadic targeting indicated that the latter provided a better account of our participants' eye movements, further supporting the hypothesis that Chinese readers "decide" where to move their eyes by adjusting saccade length in response to processing difficulty rather than by selecting default saccade targets. We discuss this hypothesis in relation to both what is known about saccadic targeting during the reading of English versus Chinese and current models of eye-movement control in reading. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Evidence of Serial Processing in Visual Word Recognition

To test the limits of parallel processing in vision, we investigated whether people can recognize two words at once. Participants viewed brief, masked pairs of words and were instructed in advance to judge both of the words (dual-task condition) or just one of the words (single-task condition). For judgments of semantic category, the dual-task deficit was so large that it supported all-or-none serial processing: Participants could recognize only one word and had to guess about the other. Moreover, participants were more likely to be correct about one word if they were incorrect about the other, which also supports a serial-processing model. In contrast, judgments of text color with identical stimuli were consistent with unlimited-capacity parallel processing. Thus, under these conditions, serial processing is necessary to judge the meaning of words but not their physical features. Understanding the implications of this result for natural reading will require further investigation.

Linguistic and nonlinguistic influences on the eyes' landing positions during reading

Two eye tracking experiments show that, for near launch sites, the eyes land nearer to the beginning of words with orthographically irregular than with regular initial letter sequences. In addition, the characteristics of words, at least at the level of orthography, influence the direction and length of within-word saccades. Importantly, these effects hold both for lower case and for visually less distinctive upper case text. Furthermore, contrary to previous evidence (Tinker & Paterson, 1939), there is little effect of type case on reading times. Additional analyses of oculomotor behaviour suggest that there is an inverted optimal viewing position for single fixation durations on words. Both the supplementary analyses and the effects of orthography on fixation positions are relevant to current models of eye movements in reading.

Eye-Movement Evidence for Object-Based Attention in Chinese Reading

Is attention allocated to only one word or to multiple words at any given time during reading? The experiments reported here addressed this question using a novel paradigm inspired by classic findings on object-based attention. In Experiment 1, participants ( N = 18) made lexical decisions about one of two spatially colocated Chinese words or nonwords. Our main finding was that only the attended word's frequency influenced response times and accuracy. In Experiment 2, participants ( N = 30) read target words embedded in two spatially colocated Chinese sentences. Our key finding here was that only target-word frequencies influenced looking times and fixation positions. These results support the hypothesis that words are attended in a strictly serial (and perhaps object-based) manner during reading. The theoretical implications of this conclusion are discussed in relation to models of eye-movement control during reading and the conceptualization of words as visual objects.

Readers extract character frequency information from nonfixated-target word at long pretarget fixations during Chinese reading

We performed 2 eye movement studies to explore whether readers can extract character or word frequency information from nonfixated-target words in Chinese reading. In Experiments 1A and 1B, we manipulated the character frequency of the first character in a 2-character target word and the word frequency of a 2-character target word, respectively. We found that fixation durations on the pretarget words were shorter when the first character of a 2-character target word was presented with high frequency. Such effects were not observed for word frequency manipulations of a 2-character target word. In particular, further analysis revealed that such effects only occurred for long pretarget fixations. These results for character and word frequency manipulations were replicated in a within-subjects design in Experiment 2. These findings are generally consistent with the notion that characters are processed in parallel during Chinese reading. However, we did not find evidence that words are processed in parallel during Chinese reading.

Word segmentation of overlapping ambiguous strings during Chinese reading

In 3 experiments, we tested 3 possible mechanisms for segmenting overlapping ambiguous strings in Chinese reading. The first 2 characters and the last 2 characters in a 3-character ambiguous string could both constitute a word in the reported studies. The left-priority hypothesis assumes that the word on the left has an advantage in the competition and the other word cannot be processed until the word on the left is recognized. The independent processing hypothesis assumes that words in different positions are processed simultaneously and independently, and the word segmentation ambiguity cannot be settled without the help of sentence context. The competition hypothesis assumes that all of the words compete for a single winner. The results support a competition account that the characters in the perceptual span activate all of the words they can constitute, and any word can win the competition if its activation is high enough.

Task relevance induces momentary changes in the functional visual field during reading

In the research reported here, we examined whether task demands can induce momentary tunnel vision during reading. More specifically, we examined whether the size of the functional visual field depends on task relevance. Forty participants read an expository text with a specific task in mind while their eye movements were recorded. A display-change paradigm with random-letter strings as preview masks was used to study the size of the functional visual field within sentences that contained task-relevant and task-irrelevant information. The results showed that orthographic parafoveal-on-foveal effects and preview benefits were observed for words within task-irrelevant but not task-relevant sentences. The results indicate that the size of the functional visual field is flexible and depends on the momentary processing demands of a reading task. The higher cognitive processing requirements experienced when reading task-relevant text rather than task-irrelevant text induce momentary tunnel vision, which narrows the functional visual field.

Reading strategy modulates parafoveal-on-foveal effects in sentence reading

Task demands and individual differences have been linked reliably to word skipping during reading. Such differences in fixation probability may imply a selection effect for multivariate analyses of eye-movement corpora if selection effects correlate with word properties of skipped words. For example, with fewer fixations on short and highly frequent words the power to detect parafoveal-on-foveal effects is reduced. We demonstrate that increasing the fixation probability on function words with a manipulation of the expected difficulty and frequency of questions reduces an age difference in skipping probability (i.e., old adults become comparable to young adults) and helps to uncover significant parafoveal-on-foveal effects in this group of old adults. We discuss implications for the comparison of results of eye-movement research based on multivariate analysis of corpus data with those from display-contingent manipulations of target words.

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.

Eye movements in reading: some theoretical context

The study of eye movements has proven to be one of the most successful approaches in research on reading. In this overview, it is argued that a major reason for this success is that eye movement measurement is not just a methodology--the control of eye movements is actually part and parcel of the dynamics of information processing within the task of reading itself. Some major developments over the last decade are discussed with a focus on the issue of spatially distributed word processing and its relation to the development of reading models. The survey ends with a description of two newly emerging trends in the field: the study of continuous reading in non-Roman writing systems and the broadening of the scope of research to encompass individual differences and developmental issues.

Parafoveal processing across different lexical constituents in Chinese reading

We report a boundary paradigm eye movement experiment to investigate whether the linguistic category of a two-character Chinese string affects how the second character of that string is processed in the parafovea during reading. We obtained clear preview effects in all conditions but, more importantly, found parafoveal-on-foveal effects whereby a nonsense preview of the second character influenced fixations on the first character. This effect occurred for monomorphemic words, but not for compound words or phrases. Also, in a word boundary demarcation experiment, we demonstrate that Chinese readers are not always consistent in their judgements of which characters in a sentence constitute words. We conclude that information regarding the combinatorial properties of characters in Chinese is used online to moderate the extent to which parafoveal characters are processed.

Parafoveal-foveal overlap can facilitate ongoing word identification during reading: evidence from eye movements

Readers continuously receive parafoveal information about the upcoming word in addition to the foveal information about the currently fixated word. Previous research (Inhoff, Radach, Starr, & Greenberg, 2000) showed that the presence of a parafoveal word that was similar to the foveal word facilitated processing of the foveal word. We used the gaze-contingent boundary paradigm (Rayner, 1975) to manipulate the parafoveal information that subjects received before or while fixating a target word (e.g., news) within a sentence. Specifically, a reader's parafovea could contain a repetition of the target (news), a correct preview of the posttarget word (once), an unrelated word (warm), random letters (cxmr), a nonword neighbor of the target (niws), a semantically related word (tale), or a nonword neighbor of that word (tule). Target fixation times were significantly lower in the parafoveal repetition condition than in all other conditions, suggesting that foveal processing can be facilitated by parafoveal repetition. We present a simple model framework that can account for these effects.

Processing of compound-word characters in reading Chinese: an eye-movement-contingent display change study

Readers' eye movements were monitored as they read Chinese two-constituent compound words in sentence contexts. The first compound-word constituent was either an infrequent character with a highly predictable second constituent or a frequent character with an unpredictable second constituent. The parafoveal preview of the second constituent was manipulated, with four preview conditions: identical to the correct form; a semantically related character to the second constituent; a semantically unrelated character to the second constituent; and a pseudocharacter. An invisible boundary was set between the two constituents; when the eyes moved across the boundary, the previewed character was changed to its intended form. The main findings were that preview effects occurred for the second constituent of the compound word. Providing an incorrect preview of the second constituent affected fixations on the first constituent, but only when the second constituent was predictable from the first. The frequency of the initial character of the compound constrained the identity of the second character, and this in turn modulated the extent to which the semantic characteristics of the preview influenced processing of the second constituent and the compound word as a whole. The results are considered in relation to current accounts of Chinese compound-word recognition and the constraint hypothesis of Hyönä, Bertram, and Pollatsek ( 2004 ). We conclude that word identification in Chinese is flexible, and parafoveal processing of upcoming characters is influenced both by the characteristics of the fixated character and by its relationship with the characters in the parafovea.

How preview space/time translates into preview cost/benefit for fixation durations during reading

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.

Parafoveal preview during reading: effects of sentence position

Two experiments examined parafoveal preview for words located in the middle of sentences and at sentence boundaries. Parafoveal processing was shown to occur for words at sentence-initial, mid-sentence, and sentence-final positions. Both Experiments 1 and 2 showed reduced effects of preview on regressions out for sentence-initial words. In addition, Experiment 2 showed reduced preview effects on first-pass reading times for sentence-initial words. These effects of sentence position on preview could result from either reduced parafoveal processing for sentence-initial words or other processes specific to word reading at sentence boundaries. In addition to the effects of preview, the experiments also demonstrate variability in the effects of sentence wrap-up on different reading measures, indicating that the presence and time course of wrap-up effects may be modulated by text-specific factors. We also report simulations of Experiment 2 using version 10 of E-Z Reader (Reichle, Warren, & McConnell, 2009), designed to explore the possible mechanisms underlying parafoveal preview at sentence boundaries.

Eye movements and brain electric potentials during reading

The development of theories and computational models of reading requires an understanding of processing constraints, in particular of timelines related to word recognition and oculomotor control. Timelines of word recognition are usually determined with event-related potentials (ERPs) recorded under conditions of serial visual presentation (SVP) of words; timelines of oculomotor control are derived from parameters of eye movements (EMs) during natural reading. We describe two strategies to integrate these approaches. One is to collect ERPs and EMs in separate SVP and natural reading experiments for the same experimental material (but different subjects). The other strategy is to co-register EMs and ERPs during natural reading from the same subjects. Both strategies yield data that allow us to determine how lexical properties influence ERPs (e.g., the N400 component) and EMs (e.g., fixation durations) across neighboring words. We review our recent research on the effects of frequency and predictability of words on both EM and ERP measures with reference to current models of eye-movement control during reading. Results are in support of the proposition that lexical access is distributed across several fixations and across brain-electric potentials measured on neighboring words.

Decisions about objects in real-world scenes are influenced by visual saliency before and during their inspection

Evidence from eye-tracking experiments has provided mixed support for saliency map models of inspection, with the task set for the viewer accounting for some of the discrepancies between predictions and observations. In the present experiment viewers inspected pictures of road scenes with the task being to decide whether or not they would enter a highway from a junction. Road safety observations have concluded that highly visible road users are less likely to be involved in crashes, suggesting that saliency is important in real-world tasks. The saliency of a critical vehicle was varied in the present task, as was the type of vehicle and the preferred vehicle of the viewer. Decisions were influenced by saliency, with more risky decisions when low saliency motorcycles were present. Given that the vehicles were invariably inspected, this may relate to the high incidence of "looked-but-failed-to-see" crashes involving motorcycles and to prevalence effects in visual search. Eye-tracking measures indicated effects of saliency on the fixation preceding inspection of the critical vehicle (as well as effects on inspection of the vehicle itself), suggesting that high saliency can attract an early fixation. These results have implications for recommendations about the conspicuity of vulnerable road users.

dlexDB – eine lexikalische Datenbank für die psychologische und linguistische Forschung

Zusammenfassung. Mit der lexikalischen Datenbank dlexDB stellen wir der psychologischen und linguistischen Forschung im World Wide Web online statistische Kennwerte für eine Vielzahl von verarbeitungsrelevanten Merkmalen von Wörtern zur Verfügung. Diese Kennwerte umfassen die durch CELEX ( Baayen, Piepenbrock und Gulikers, 1995 ) bekannten Variablen der Häufigkeiten von Wortformen und Lemmata in Texten geschriebener Sprache. Darüber hinaus berechnen wir eine Reihe neuer Kennwerte wie die Häufigkeiten von Silben, Morphemen, Zeichenfolgen und Mehrwortverbindungen sowie Wortähnlichkeitsmaße. Die Datengrundlage bildet das Kernkorpus des Digitalen Wörterbuchs der deutschen Sprache (DWDS) mit über 100 Millionen laufenden Wörtern. Wir illustrieren die Validität dieser Kennwerte mit neuen Ergebnissen zu ihrem Einfluss auf Fixationsdauern beim Lesen von Sätzen.

Parafoveal processing during reading is reduced across a morphological boundary

A boundary change manipulation was implemented within a monomorphemic word (e.g., fountaom as a preview for fountain), where parallel processing should occur given adequate visual acuity, and within an unspaced compound (bathroan as a preview for bathroom), where some serial processing of the constituents is likely. Consistent with that hypothesis, there was no effect of the preview manipulation on fixation time on the 1st constituent of the compound, whereas there was on the corresponding letters of the monomorphemic word. There was also a larger preview disruption on gaze duration on the whole monomorphemic word than on the compound, suggesting more parallel processing within monomorphemic words.

Development of parafoveal processing within and across words in reading: evidence from the boundary paradigm

In this study we used the boundary paradigm to examine whether readers extract more parafoveal information within than across words. More specifically, we examined whether readers extract more parafoveal information from a compound word's second constituent than from the same word when it is the noun in an adjective-noun phrase (kummitustarina "ghost story" vs. lennokas tarina "vivid story"). We also examined whether the processing of compound word constituents is serial or parallel and how parafoveal word processing develops over the elementary school years. Participants were Finnish adults and 8-year-old second-, 10-year-old fourth-, and 12-year-old sixth-graders. The results showed that for all age groups more parafoveal information is extracted from the second constituent within compounds than from the noun in adjective-noun phrases. Moreover, for all age groups we found evidence for parallel processing of constituents within compounds, but only when the compounds were of high frequency. In sum, the present study shows that attentional allocation extends further to the right and is more simultaneous when words are linguistically and spatially unified, providing evidence that attention in text processing is flexible in nature.

The 35th Sir Frederick Bartlett Lecture: Eye movements and attention in reading, scene perception, and visual search

Eye movements are now widely used to investigate cognitive processes during reading, scene perception, and visual search. In this article, research on the following topics is reviewed with respect to reading: (a) the perceptual span (or span of effective vision), (b) preview benefit, (c) eye movement control, and (d) models of eye movements. Related issues with respect to eye movements during scene perception and visual search are also reviewed. It is argued that research on eye movements during reading has been somewhat advanced over research on eye movements in scene perception and visual search and that some of the paradigms developed to study reading should be more widely adopted in the study of scene perception and visual search. Research dealing with “real-world” tasks and research utilizing the visual-world paradigm are also briefly discussed.

The influence of punctuation and word class on distributed processing in normal reading

A series of multiple regression analyses was conducted on a corpus of eye movement data to examine whether the influence of properties of words n-1 and n+1 on the time spent fixating word n changes as a function of whether word n is associated with a punctuation mark (i.e., whether or not a punctuation mark separates word n from either word n-1 or word n+1). The results suggest that distributed processing is not significantly impaired. However, punctuation marks also carry word class information and word classes are not evenly distributed across positions relative to punctuation marks. Word class probability does modulate parafoveal-on-foveal effects.

An influence over eye movements in reading exerted from beyond the level of the word: Evidence from reading English and French

We report the results of a series of multiple regression analyses conducted on the Dundee Corpus, a corpus of eye-movement data obtained from ten British and ten French young adults as they read newspaper articles (the equivalent of more than 52,000 words per language) presented on a screen, five lines at a time. Inspection parameters (inter-word saccade latency, saccade extent, skipping probability, first fixation and gaze duration and number of fixation) were all determined in part by properties defined beyond the level of individual words, e.g., the relative or mean length of adjacent words rather than individual word length. Properties defined at this level do not feature in any current model of eye-movement control in reading. Moreover, foveal inspection time was found to vary as a function of the properties of words in the parafovea (lexical frequency for English; initial trigram informativeness for French). We account for these results by proposing a process monitoring mechanism, in which a number of visual parameters simultaneously contribute to optimize visibility over a sequence of adjacent words.

Reaction Time Reduction after Parafoveal Preview in a Lexical Decision Task

Time and the accuracy of a lexical decision performed on a letter string (either a word or nonword), presented foveally after a parafoveal preview displayed at 5° of eccentricity and 100 msec. duration were measured. Students of Padova University, 10 women and 7 men, ages 19 to 23 years were subjects. The hypothesis investigated was whether the facilitatory effect, a reduction in lexical decision time due to the parafoveal preview, was tied to global visual information acquired in the visual periphery during the preview presentation. In Exp. 1, eight subjects performed the task either with no preview (No Preview) or with a preview presented at 5° eccentricity in two conditions, preview of the same foveal string (Preview-Letters) and preview of symbols (“xxx …”) of the same length as the foveal string (Preview Symbols). In Exp. 2, 9 subjects performed the task with two preview conditions, No Preview and preview of the foveal string in uppercase letters at 5° of eccentricity (Preview Uppercase). Analyses suggested the reduction in lexical decision time due to the Preview with respect to the No Preview condition is tied to global information extracted during parafoveal presentation. The reduction in lexical decision time depends on word texture, i.e., letters' identities and also word boundary, in addition to word length.

Tests of the E-Z Reader model: Exploring the interface between cognition and eye-movement control

This paper is simultaneously a test and refinement of the E-Z Reader model and an exploration of the interrelationship between visual and language processing and eye-movements in reading. Our modeling indicates that the assumption that words in text are processed serially by skilled readers is a viable and attractive hypothesis, as it accounts not only for "normal" reading data, but also for the pattern of decrements that occur when text is withheld from view during certain periods of time, such as in the boundary paradigm and the disappearing text paradigm. Our analyses also indicate (a) that lexical processing during reading is essentially continuous and (b) that the trigger for eye movements has to be a different (and prior) event to the trigger for shifts of covert spatial attention. In addition, the parameter values in our model are in accordance with what is known about such processes and should be taken as serious hypotheses for how long these processes last. Although a parallel model may be able to duplicate the predictions of the E-Z Reader model, we think that it is likely to be far less parsimonious and not nearly as good a heuristic device for using eye movements to understand language processing in reading.

Parafoveal-on-foveal effects on eye movements in text reading: Does an extra space make a difference?

Schiepers proposed that in text reading, the currently fixated word and the next word are processed in parallel but with a time delay of 90 ms per degree of eccentricity. In his model, the benefit of seeing the upcoming word is due to the fact that the parafoveal information from fixation n is combined with the foveal information from fixation n+1 to boost word recognition, at least when the fixation on word n is of an optimal duration (between 210 and 270 ms). We tested this assumption by adding an extra blank space between the foveal and the parafoveal word. According to the model, this should result in a 30 ms longer processing time for the foveal word. However, reading time was shorter for a word followed by a double space than for a word followed by a single space. An effect of parafoveal word length was also observed with a longer word in the parafoveal leading to shorter fixation times on the foveal word. Implications of these low-level parafoveal-on-foveal effects are discussed.

Parafoveal-on-foveal effects in normal reading

A corpus of eye movement data derived from 10 English and 10 French participants, each reading about 50,000 words, was examined for evidence that properties of a word in parafoveal vision have an immediate effect on foveal inspection time. When inspecting a short word, there is evidence that the lexical frequency of an adjacent word affects processing time. When inspecting a long word, there are small effects of lexical frequency, but larger effects of initial-letter constraint and orthographic familiarity. Interactions of this kind are incompatible with models of reading which appeal to the operation of a serial attention switch.

The implications of foveal splitting for saccade planning 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.

"Bottom-up" and "top-down" effects on reading saccades: a case study

OBJECTIVE

To investigate the role right foveal/parafoveal sparing plays in reading single words, word arrays, and eye movement patterns in a single case with an incongruous hemianopia.

METHODS

The patient, a 48-year-old right handed male with a macular sparing hemianopia in his left eye and a macular splitting hemianopia in his right eye, performed various reading tasks. Single word reading speeds were monitored using a "voice-trigger" system. Eye movements were recorded while reading three passages of text, and PET data were gathered while the subject performed a variety of reading tasks in the camera.

RESULTS

The patient was faster at reading single words and text with his left eye compared with his right. A small word length effect was present in his right eye but not his left. His eye movement patterns were more orderly when reading text with his left eye, making fewer saccades. The PET data provided evidence of "top-down" processes involved in reading. Binocular single word reading produced activity in the representation of foveal V1 bilaterally; however, text reading with the left eye only was associated with activation in left but not right parafoveal V1, despite there being visual stimuli in both visual fields.

CONCLUSIONS

The presence of a word length effect (typically associated with pure alexia) can be caused by a macular splitting hemianopia. Right parafoveal vision is not critically involved in single word identification, but is when planning left to right reading saccades. The influence of top-down attentional processes during text reading can be visualised in parafoveal V1 using PET.

Low-level predictive inference in reading: the influence of transitional probabilities on eye movements

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.

Parafoveal-on-foveal interactions in word recognition

An experiment is reported in which participants read sequences of five words, looking for items describing articles of clothing. The third and fourth words in critical sequences were defined as "foveal" and "parafoveal" words, respectively. The length and frequency of foveal words and the length, frequency, and initial-letter constraint of parafoveal words were manipulated. Gaze and refixation rate on the foveal word were measured as a function of properties of the parafoveal word. The results show that measured gaze on a given foveal word is systematically modulated by properties of an unfixated parafoveal word. It is suggested that apparent inconsistencies in previous studies of parafoveal-on-foveal effects relate to a failure to control for foveal word length and hence the visibility of parafoveal words. A serial-sequential attention-switching model of eye movement control cannot account for the pattern of obtained effects. The data are also incompatible with various forms of parallel-processing model. They are best accounted for by postulating a process-monitoring mechanism, sensitive to the simultaneous rate of acquisition of information from foveal and parafoveal sources.

Eye movements and processing stages in reading: relative contribution of visual, lexical, and contextual factors

The independent and the combined influence of word length, word frequency, and contextual predictability on eye movements in reading was examined across processing stages under two priming-context conditions. Length, frequency, and predictability were used as predictors in multiple regression analyses, with parafoveal, early, late, and spillover eye movement measures as the dependent variables. There were specific effects of: (a) length, both on where to look (how likely a word was fixated and in which location) and how long to fixate, across all processing stages; (b) frequency, on how long to fixate a word, but not on where to look, at an early processing stage; and (c) predictability, both on how likely a word was fixated and for how long, in late processing stages. The source of influence for predictability was related to global rather than to local contextual priming. The contribution of word length was independent of contextual source. These results are relevant to determine both the time course of the influence of visual, lexical, and contextual factors on eye movements in reading, and which main component of eye movements, that is, location or duration, is affected.

A dynamical model of saccade generation in reading based on spatially distributed lexical processing

The understanding of the control of eye movements has greatly benefited from the analysis of mathematical models. Currently most comprehensive models include sequential shifts of visual attention. Here we propose an alternative model of eye movement control, which includes three new principles: spatially distributed lexical processing, a separation of saccade timing from saccade target selection, and autonomous (random) generation of saccades with foveal inhibition. These three features provide a common control mechanism for fixations, refixations, and regressions. Consequently, the model is called SWIFT (Saccade-generation with inhibition by foveal targets). Results from numerical simulations are in good agreement with effects of word frequency on single-fixation, first-fixation, and gaze durations as well as fixation and word skipping probabilities in first-pass analysis. The model inherently produces complex eye movement patterns including refixations and regressions due to its underlying dynamical principles.

The eye movements of pure alexic patients during reading and nonreading tasks

We compared the eye-movements of two patients who read letter-by-letter (LBL) following a left occipital lobe lesion with those of normal control subjects and of hemianopic patients in two tasks: a nonreading visual search task and a text reading task. Whereas the LBL readers exhibited similar eye-movement patterns to those of the other two groups on the nonreading task, their eye movements differed significantly during reading, as reflected in the disproportionate increase in the number and duration of fixations per word and in the regressive saccades per word. Importantly, relative to the two control groups, letter-by-letter readers also made more fixations per word as word length increased, especially as word frequency and word imageability decreased. Two critical results emerged from these experiments: First, the alteration in the oculomotor behavior of the LBL readers during reading is similar to that seen in normal readers under difficult reading conditions, as well as in beginning readers and in those with developmental dyslexia, and appears to reflect difficulties in processing the visual stimulus. Second, the interaction of length with frequency and with imageability in determining the eye movement pattern is consistent with an interactive activation model of normal word recognition in which weakened activation of orthographic input can nevertheless engage high-level lexical factors.