Integrating information across eye fixations in reading: the role of letter and word units

Eye movements and eye fixations were recorded to study the integration of letter/word information across interword fixations in reading. Two hypotheses were examined. One hypothesis posits that readers obtain effective information from the beginning two or three letters of a parafoveal word. This information facilitates the recognition of the word when it is being fixated. The alternative posits that effective information is obtained from the complete parafoveal word. The results of the present study showed faster reading rates when parafoveal previews comprised complete words than when they comprised beginning letters alone. Furthermore, the usability of parafoveally available partial word information from beginning and ending letters was not affected by small variations in retinal eccentricity. Both findings were taken as evidence that readers gain useful information from all letters of the parafoveally available word and that whole word information, rather than specific letter information, is integrated across interword fixations in reading.     

Eye Movement Control During Reading: Foveal Load and Parafoveal Processing

We tested theories of eye movement control in reading by looking at parafoveal processing. According to attention-processing theories, attention shifts towards word n+1 only when processing of the fixated word n is finished, so that attended parafoveal processing does not start until the programming of the saccade programming to word n+1 is initiated (Henderson & Ferreira, 1990; Morrison, 1984), or even later when the processing of word n takes too long (Henderson & Ferreira, 1990). Parafoveal preview benefit should be constant whatever the foveal processing load (Morrison, 1984), or should decrease when processing word n outlasts an eye movement programming deadline (Henderson & Ferreira, 1990). By manipulating the frequency and length of the foveal word n and the visibility of the parafoveal word n+1 , we replicated the finding that the parafoveal preview benefit is smaller with a low-frequency word in foveal vision. Detailed analyses, however, showed that the eye movement programming deadline hypothesis could not account for this finding which was due not to cases where the low-frequency words n had received a long fixation, but to cases of a short fixations less than 240 msec. In addition, there was a spill-over effect of word n to word n+1 , and there was an element of parallel processing of both words. The results are more in line with parallel processing limited by the extent to which the parafoveal word processing on fixation n can be combined with the foveal word processing on fixation n+1 .     

Masking of foveal and parafoveal vision during eye fixations in reading

A window or visual mask as moved across text in synchrony with the reader's eye movements. The size of the window or mask was varied so that either information in foveal or parafoveal vision was masked on each fixation. In another experiment, the onset of the mask was delayed for a certain amount of time following the end of the saccade. The results of the experiments point out the relative importance of foveal and parafoveal vision for reading and further indicate that most of the visual information necessary for reading can be acquired during the first 50 msec that information is available during an eye fixation.     

Parafoveal processing in word recognition

Two experiments investigated the degree to which properties of a word presented in the parafovea influenced the time to process a word undergoing concurrent foveal inspection. In Experiment 1, subjects viewed a set of five-letter words at a fixed point, with words in parafoveal vision varying in length, word frequency, and both the type and token frequency of occurrence of their initial three letters. The results showed that the frequency of the target and the type frequency of its initial letters influenced foveal fixation time. In Experiment 2, subjects executed a sequence of saccades before initial fixation on the experimental items. Under these circumstances, fixation time was shorter overall. Lexical properties of parafoveal words had no effect on foveal processing, but the length and the type frequency of their initial letters exerted a strong influence. Parafoveal-on-foveal effects of this form are incompatible with models of reading in which attention is allocated sequentially to successive words. The data are more consistent with the proposition that foveal and parafoveal processing occurs in parallel, with processing distributed over a region larger than a single word. Subsidiary analyses showed little influence of any of the manipulated variables on saccade extent.     

Do frequency characteristics of nonfixated words influence the processing of fixated words during reading?

Are readers capable of lexically processing more than one word at a time? In five eye movement experiments, we examined to what extent lexical characteristics of the nonfixated word to the right of fixation influenced readers' eye behaviour on the fixated word. In three experiments, we varied the frequency of the initial constituent of two‐noun compounds, while in two experiments the whole‐word frequency was manipulated. The results showed that frequency characteristics of the parafoveal word sometimes affected eye behaviour prior to fixating it, but the direction of effects was not consistent and the effects were not replicated across all experiments. Follow‐up regression analyses suggested that foveal and parafoveal word length as well as the frequency of the word‐initial trigram of the parafoveal word may modulate the parafoveal‐on‐foveal effects. It is concluded that low‐frequency words or lexemes may under certain circumstances serve as a magnet to attract an early eye movement to them. However, further corroborative evidence is clearly needed.     

The influence of parafoveal typographical errors on eye movements in reading

Three experiments are reported, examining the effects of a typographical error in parafoveal vision on aspects of foveal inspection time and saccade targeting. All the experiments involved reading for comprehension. A contingent presentation procedure ensured that typographical errors were restored to their correct form before they were viewed in foveal vision: They were never available for foveal processing. In Experiment 1, the error was formed by replacing the first letter of the target word with a second occurrence of its second letter, producing an illegal nonword. This manipulation had no significant effect on foveal inspection time, but lowered the probability that a short word (“de” or “du”) prior to the target would be skipped. In Experiment 2 the familiarity of the target's initial letters was maintained constant across conditions. This manipulation removed the target 1 skipping effect, suggesting that the outcome of Experiment 1 was due to orthographic rather than lexical illegality, but revealed shorter foveal inspection times as a function of the presence of the error. Experiment 3 manipulated lexical and sublexical properties of the parafoveal typing error. Properties of the parafoveal error again influenced prior foveal inspection times. The pattern of results suggested that the determining properties were sublexical rather than lexical. The results as a whole are incompatible with a view of information processing in reading in which foveal processing remains immune from concurrent parafoveal influences.     

Effects of parafoveal word length and orthographic features on initial fixation landing positions in reading

Previous research has demonstrated that readers use word length and word boundary information in targeting saccades into upcoming words while reading. Previous studies have also revealed that the initial landing positions for fixations on words are affected by parafoveal processing. In the present study, we examined the effects of word length and orthographic legality on targeting saccades into parafoveal words. Long (8?C9 letters) and short (4?C5 letters) target words, which were matched on lexical frequency and initial letter trigram, were paired and embedded into identical sentence frames. The gaze-contingent boundary paradigm (Rayner, 1975) was used to manipulate the parafoveal information available to the reader before direct fixation on the target word. The parafoveal preview was either identical to the target word or was a visually similar nonword. The nonword previews contained orthographically legal or orthographically illegal initial letters. The results showed that orthographic preprocessing of the word to the right of fixation affected eye movement targeting, regardless of word length. Additionally, the lexical status of an upcoming saccade target in the parafovea generally did not influence preprocessing.     

Latency dependence of word-initial letter integration by the saccadic system

Two experiments are reported in which saccadic eye movements were examined when the eyes moved to words in which the properties of the word-initial letters differed. It was found that the effect of saccade latency on landing position depended on the properties of the word-initial letters. Under short saccade latencies, landing positions deviated toward the word beginning in the presence of orthographically irregular/informative beginning (OI/IB) letters. This result is interpreted as an influence of the orthographic encoding process that has detected an unusual letter grouping. With longer saccade latencies, an increase of the saccade size was observed for OI/IB words, whereas orthographically regular/uninformative beginning words did not show the effect. It is suggested that this may be a consequence of the dynamics of parafoveal word information processing.     

Lexical integration across saccades in reading

Summary Eye movements were recorded during sentence reading to examine the integration of parafoveal text across fixations. Four viewing conditions were used, each affording full view of the directly fixated word: no preview of the spatially adjacent parafoveal word; preview of its beginning trigram; preview of its beginning four letters; or preview of all its constituent letters. The magnitude of parafoveal-preview benefits (the difference between the no-preview condition and the different parafoveal-preview conditions) was examined as a function of the size of the saccade to the parafoveal target and as a function of the subsequent fixation location at the previewed target. The results revealed no effects of saccade size on parafoveal-preview benefits, but large effects of fixation position during the initial target fixation. Furthermore, parafoveal previews were used during the initial target fixation and during subsequent intratarget refixations. The results support a lexical-text-integration hypothesis which posits that lexical information is integrated across interword fixations and intraword refixations.     

Parafoveal processing of words and saccade computation during eye fixations in reading

Studied parafoveal word processing during eye fixations in reading to answer two questions: (a) Is the processing of parafoveally available words limited to the identification of beginning letters? (b) Does the parafoveal processing of words affect the following interword saccade? Reading afforded either no parafoveal preview, preview of beginning trigrams, preview of ending trigrams, or preview of the whole parafoveal word. Previews were controlled by replacing original letters either with X's or dissimilar letters. Preview benefits were larger for the whole word previews than for beginning or ending trigram previews. X-masks yielded preview benefits from intact beginning and ending trigrams but dissimilar letter masks yielded benefits from beginning trigrams only. Saccades were larger for whole word previews than for no previews. These results support Logogen-type models of word recognition and a model of saccade computation that posits a time-locked functional relation between the acquisition of parafoveal word information and the positioning of each fixation.     

Effects of foveal processing difficulty on the perceptual span in reading: implications for attention and eye movement control

Two experiments were conducted to examine the effects of foveal processing difficulty on the perceptual span in reading. Subjects read sentences while their eye movements were recorded. By changing the text contingent on the reader's current point of fixation, foveal processing difficulty and the availability of parafoveal word information were independently manipulated. In Experiment 1, foveal processing difficulty was manipulated by lexical frequency, and in Experiment 2 foveal difficulty was manipulated by syntactic complexity. In both experiments, less parafoveal information was acquired when processing in the fovea was difficult. We conclude that the perceptual span is variable and attentionally constrained. We also discuss the implications of the results for current models of the relation between covert visual-spatial attention and eye movement control in reading.     

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.     

Parafoveal Magnification: Visual Acuity Does Not Modulate the Perceptual Span in Reading

ABSTRACT— Models of eye guidance in reading rely on the concept of the perceptual span—the amount of information perceived during a single eye fixation, which is considered to be a consequence of visual and attentional constraints. To directly investigate attentional mechanisms underlying the perceptual span, we implemented a new reading paradigm—parafoveal magnification (PM)—that compensates for how visual acuity drops off as a function of retinal eccentricity. On each fixation and in real time, parafoveal text is magnified to equalize its perceptual impact with that of concurrent foveal text. Experiment 1 demonstrated that PM does not increase the amount of text that is processed, supporting an attentional-based account of eye movements in reading. Experiment 2 explored a contentious issue that differentiates competing models of eye movement control and showed that, even when parafoveal information is enlarged, visual attention in reading is allocated in a serial fashion from word to word.     

Eye movement guidance in reading: the role of parafoveal letter and space information

The relation between parafoveal letter and space information in eye movement guidance during reading was investigated in 2 experiments. Contingent upon the reader's fixation, the type of parafoveal information available to the right of fixation was varied by (a) space information only, (b) space information with letter information added at some delay, or (c) letter and space information simultaneously. In addition, the onset of the relevant parafoveal information was delayed between 0 and 250 ms into the fixation. The time course of processing the 2 types of information (letters or spaces) differed, as did the nature of their impact on the eye movement record. Although both letter and space information influenced saccade length and initial landing positions within words, only letter information had an effect on fixation duration. In addition, fixation duration was affected only by information entering within the first 50 ms of the fixation, whereas saccade length was affected by information arriving at any time during the fixation. The results are consistent with a model of eye movement control in which 2 independent processes are operating in tandem to determine when and where to move the eyes during reading.     

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 degrees 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 degrees eccentricity in two conditions, preview of the same foveal string (Preview-Letters) and preview of symbols ("x xx...") 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 degrees 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.     

中央凹加工负荷与副中央凹信息在汉语阅读眼跳目标选择中的作用

研究探讨汉语读者选择眼跳目标时, 中央凹注视词的加工负荷是否影响副中央凹获取信息量, 进而调节随后的眼跳长度。采用眼动追踪技术, 操纵了中央凹注视词的词频(高频、低频)和副中央凹词的笔画数(多笔画、少笔画)。结果发现：从中央凹词到副中央凹少笔画词的眼跳长度显著地长于到多笔画词的, 且这种笔画数效应并不受中央凹加工负荷的调节; 从高频中央凹词到副中央凹词的眼跳长度显著地长于低频词的。在本实验条件下结果提示：中央凹加工负荷在眼跳目标选择中的作用不是通过调节副中央凹获取信息量的多少来实现的。     

先前语境与随后副中央凹预视在词跳读中的相对作用

词跳读促使了阅读高效地进行。被跳读的词主要根据前文语境和副中央凹预视提前得到加工。分析跳读的影响因素可知,相比于语境因素（特别是预测性）和副中央凹词汇因素（如词频）,副中央凹词的视觉词长信息对跳读的影响最大。跳读密切联系当前眼动控制的两大内容,理想的阅读眼动控制模型需区别语境不同信息（即预测性、语义合理性和句法合理性）对跳读的作用。未来可扩展中文跳读的研究,解决中文跳读单元问题及相关争论。     

阅读中的眼跳目标选择问题

读者在阅读中面临如何选择眼跳落点位置的问题。研究者在有词间空格的字母文字中(如英语和德语)发现人们倾向于将眼跳落在词中心偏左的位置,这个位置被称为偏好注视位置(preferred viewing location,PVL)。中文文本并没有空格来标记词边界信息,这使得中文阅读的眼跳目标选择机制更加复杂。近年来,研究者从中央凹—副中央凹动态调节的角度研究了阅读中眼跳目标选择的机制。结果发现在中文阅读中眼跳目标选择受到中央凹和副中央凹信息加工的共同影响,而副中央凹的加工直接决定了眼跳落点位置。     

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.     

A test of parafoveal‐on‐foveal effects with pairs of orthographically related words

One of the main controversies in the field of eye movements in reading concerns the question of whether the processing of two adjacent words in reading occurs in sequence, or in parallel. To distinguish between these views, the present experiment tested the presence of parafoveal‐on‐foveal effects with pairs of orthographically related words (or neighbours that differed by a single letter) in a controlled but reading‐like situation. Results revealed that fixation times on a foveal target word were shorter when the target was accompanied by an orthographically similar parafoveal word than when the parafoveal word was dissimilar. Furthermore, the size of the effect tended to vary with both the relative frequency of target and parafoveal words, and the position of the critical letter. These results were interpreted in the framework of a pure parallel processing hypothesis, where the processing of adjacent words is only limited by visual acuity, and the respective lexical properties of the foveal and parafoveal words.