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 .     

Influences on and consequences of parafoveal preview in reading

During reading, information is extracted from upcoming words to the right of the currently fixated word, which facilitates recognition of those words when they are later fixated. According to the foveal load hypothesis (Henderson & Ferreira, 1990), this parafoveal preview benefit depends on how difficult the currently fixated word is to recognize. Furthermore, there is evidence that the influence of lexical variables (frequency and predictability) on word processing changes when no preview of that word is available. The present study reports two moving-window experiments in which the upcoming word to the right of fixation was either included in or excluded from the window. Through this manipulation, accurate parafoveal information was either available or not for each word in the paragraph. Two critical interactions between preview condition and lexical variables were observed. First, the word frequency at word N was found to be the primary influence on the amount of preview benefit obtained at word N+1, consistent with the foveal load hypothesis. Second, denial of preview eliminated the word predictability effect. These findings have implications for models of eye movement control in reading.     

A theoretical analysis of the perceptual span based on SWIFT simulations of the n + 2 boundary paradigm

Eye-movement experiments suggest that the perceptual span during reading is larger than the fixated word, asymmetric around the fixation position, and shrinks in size contingent on the foveal processing load. We used the SWIFT model of eye-movement control during reading to test these hypotheses and their implications under the assumption of graded parallel processing of all words inside the perceptual span. Specifically, we simulated reading in the boundary paradigm and analysed the effects of denying the model to have valid preview of a parafoveal word n + 2 two words to the right of fixation. Optimizing the model parameters for the valid preview condition only, we obtained span parameters with remarkably realistic estimates conforming to the empirical findings on the size of the perceptual span. More importantly, the SWIFT model generated parafoveal processing up to word n + 2 without fitting the model to such preview effects. Our results suggest that asymmetry and dynamic modulation are plausible properties of the perceptual span in a parallel word-processing model such as SWIFT. Moreover, they seem to guide the flexible distribution of processing resources during reading between foveal and parafoveal words.     

快速与慢速读者的中央凹加工对副中央凹预视的影响

在中文阅读中, 预视量是否存在个体差异及其是否受中央凹加工调节, 尚不清楚。本研究采用眼动技术和边界范式, 通过操纵前目标词的加工负荷(高、低)与目标词的预视(相同、假字)来考察快速与慢速读者的中央凹加工对副中央凹预视的影响。结果显示, 中央凹负荷主效应显著; 快速读者对低负荷词的首次和单次注视短于高负荷词, 而慢速读者对两种负荷词的首次和单次注视无差异, 表明快速读者能更快利用词汇特性加工中央凹词汇。预视主效应显著, 即与假字预视相比, 相同预视使两组读者都对目标词的注视更短、向前眼跳更长、跳读率更高; 而且该效应与中央凹负荷没有交互作用。这表明快速读者与慢速读者提取了等量预视, 且不受其中央凹加工的调节。E-Z读者模型和SWIFT模型不能完全解释当前结果。     

Parafoveal processing in reading

The present review summarizes research investigating how words are identified parafoveally (and foveally) in reading. Parafoveal and foveal processing are compared when no other concurrent task is required (e.g., in single-word recognition tasks) and when both are required simultaneously (e.g., during reading). We first review methodologies used to study parafoveal processing (e.g., corpus analyses and experimental manipulations, including gaze-contingent display change experiments such as the boundary, moving window, moving mask, and fast priming paradigms). We then turn to a discussion of the levels of representation at which words are processed (e.g., orthographic, phonological, morphological, lexical, syntactic, and semantic). Next, we review relevant research regarding parafoveal processing, summarizing the extent to which words are processed at each of those levels of representation. We then review some of the most controversial aspects of parafoveal processing, as they relate to reading: (1) word skipping, (2) parafoveal-on-foveal effects, and (3) n + 1 and n + 2 preview benefit effects. Finally, we summarize two of the most advanced models of eye movements during reading and how they address foveal and parafoveal processing.     

2~5年级小学生汉字识别中预视效应的发展研究

在阅读时,读者可以获取副中央凹处的词汇信息,副中央凹加工是构成流畅阅读的重要因素。本研究从儿童语言发展的角度,通过3个实验（共534名被试）,考察了汉语视觉字词加工中2~5年级学生的字形、语音、语义预视效应。结果发现：（1）2~5年级小学生均有字形预视效应;（2）2、3年级学生没有语音预视效应,4、5年级学生有此效应;（3）2年级学生没有语义预视效应,3、4、5年级学生有此效应。这表明,低水平的视觉信息—字形信息在儿童副中央凹加工中一直稳定地发挥作用;高水平的语言信息—语音和语义信息,随着儿童年级的升高和阅读技能的提升,逐渐地在儿童的副中央凹加工中发挥作用。儿童对汉字各类型信息的获取与使用的发展模式不同于拼音文字阅读发展理论的预测。     

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.     

中文阅读过程中的副中央凹预视效应

副中央凹预视效应指当读者正注视某个词(即位于中央凹的词n)时, 可以获得词n右侧词(即位于副中央凹词n+1或词n+2)的部分信息。在阅读过程中读者能否从副中央凹预视到信息, 会直接影响他们的阅读效率。因此, 探讨阅读过程中的副中央凹预视效应产生的条件、影响因素及机制, 成为阅读心理学需要解决的基本问题之一。本文系统总结了中外文阅读过程中副中央凹预视效应的研究进展, 包括副中央凹预视效应的研究范式, 中外文阅读过程中副中央凹预视的信息类型、不同类型信息预视加工的时间进程, 以及空间上获得预视信息的范围。最后提出中文阅读过程中副中央凹预视研究需要解决的几个关键问题。     

语境预测性对中文高低阅读技能儿童预视加工的影响

采用呈现随注视变化的边界范式(boundary paradigm),操作目标词的语境预测性和预视类型,考察高、低阅读技能儿童在词汇预视加工中语境预测效应的差异。结果发现,高、低阅读技能儿童对语境预测性的使用在发生时程上存在差异,高阅读技能儿童从词汇副中央凹预视加工阶段开始利用语境预测性信息,而低阅读技能儿童则在加工晚期更加依赖语境预测性信息,符合预测编码框架理论对儿童语境预测性效应差异的解释。     

Early morphological effects in reading: Evidence from parafoveal preview benefit in Hebrew

Hebrew words are composed of two interwoven morphemes: a triconsonantal root and a word pattern. We examined the role of the root morpheme in word identification by assessing the benefit of presentation of a parafoveal preview word derived from the same root as a target word. Although the letter information of the preview was not consciously perceived, a preview of a word derived from the same root morpheme as the foveal target word facilitated eye-movement measures of first-pass reading (i.e.,first fixation and gaze duration). These results are the first to demonstrate early morphological effects in the context of sentence reading in which no external task is imposed on the reader, and converge with previous findings of morphemic priming in Hebrew using the masked priming paradigm, and morphemic parafoveal preview benefit effects in a single-word identification task.     

副中央凹低频双字词首字字频的预视效应研究

为探讨副中央凹字的加工负荷在预视加工中的作用,选择高、低首字字频的低频双字词作为副中央凹目标词,同时采用边界范式操纵目标词首字的预视类型（包括目标预视和假字预视）。使用眼动仪记录读者的阅读过程。结果在目标词首字与整词上均发现了显著的预视效应,目标预视下的注视时间显著短于假字预视下的注视时间;在目标词的凝视时间和总注视时间上,字频主效应显著,首字低频条件下的注视时间显著长于首字高频条件;但没有发现两因素的交互作用。结果表明副中央凹低频双字词首字字频并不影响预视效应的大小。     

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。     

Eye movements and word skipping during reading revisited

The authors examined word skipping in reading in 2 experiments. In Experiment 1, skipping rates were higher for a preview of a predictable word than for a visually similar nonword, indicating there is full recognition in parafoveal vision. In Experiment 2, foveal load was manipulated by varying the frequency of the word preceding either a 3-letter target word or a misspelled preview. There was again a higher skipping rate for a correct preview and a lower skipping rate when there was a high foveal load, but there was no interaction, and the pattern of effects in fixation times was the same as in the skipping data. Experiment 2 also showed significant skipping of nonwords similar to the target word, indicating skipping based on partial information.     

Is emotional content obtained from parafoveal words during reading? An eye movement analysis

An eye-movement-contingent display change technique was employed to study whether adult readers extract semantic information from parafoveal words during reading. Three types of parafoveal preview conditions were contrasted: an emotional word, a neutral word, and an identical word condition. To have a maximally effective parafoveal manipulation, high-arousal emotional words (sex- and threat-related and curse words) were used as parafoveal previews. Readers' eye fixation patterns around the target word revealed no evidence for parafoveal semantic processing. Furthermore, the pupil size showed no signs for an emotional response triggered by an emotional word previewed parafoveally. These results are consistent with the view that, as a rule, only the fixated word is processed to a semantic level during reading.     

Word processing in the parafoveal region

This study examined the role of words viewed in the parafoveal region during reading. In contrast to previous work, the present experiments used a reading-aloud paradigm that was postulated to encourage letter-to-sound processing, as is typical for beginning readers and for skilled readers who are reading difficult material. The three experiments in this study examined the role of orthographic and semantic information in the parafoveal region on the processing of a word in the foveal region. For this, two words, one in the foveal region and the other in the parafoveal region, were presented side by side to resemble normal reading. Participants were instructed to read aloud the word on the left side, ignoring the word on the right side. Experiments 1 and 2 showed that the presence of a word in the parafoveal region slowed naming of target words, and that this delay was attributable to linguistic interference. This pattern indicates that the information in the parafoveal region affect the processing of the target. Experiment 3 showed an effect of parafoveal semantic information on processing of the target word. In sum the results of the current study suggest that information in the parafoveal region appears to be linguistically processed but to a weaker degree than the focused word. In sum, the results of the experiments in the current study indicate that the influence of parafoveal information is quite lexical and semantic information in the parafoveal region affects processing of the target in the foveal region.     

Adult age differences in the perceptual span during reading

Following up on research suggesting an age-related reduction in the rightward extent of the perceptual span during reading (Rayner, Castelhano, & Yang, 2009), we compared old and young adults in an N + 2-boundary paradigm in which a nonword preview of word N + 2 or word N + 2 itself is replaced by the target word once the eyes cross an invisible boundary located after word N. The intermediate word N + 1 was always three letters long. Gaze durations on word N + 2 were significantly shorter for identical than nonword N + 2 preview both for young and for old adults, with no significant difference in this preview benefit. Young adults, however, did modulate their gaze duration on word N more strongly than old adults in response to the difficulty of the parafoveal word N + 1. Taken together, the results suggest a dissociation of preview benefit and parafoveal-on-foveal effect. Results are discussed in terms of age-related decline in resilience towards distributed processing while simultaneously preserving the ability to integrate parafoveal information into foveal processing. As such, the present results relate to proposals of regulatory compensation strategies older adults use to secure an overall reading speed very similar to that of young adults.     

聋人副中央凹字N+1预视效益的眼动研究

聋人听觉受损后,在低水平的视觉认知任务中,表现出副中央凹注意增强效应。这种增强效应是否也会发生在高水平的汉语认知加工任务中？本研究采用边界范式,探究副中央凹注意增强效应对聋人读者合体字N+1预视效益的影响。研究发现,高技能聋人读者,可以获得合体字N+1语音和语义预视效益。研究表明,副中央凹注意增强促进了高技能聋人读者N+1预视信息的获得。     

副中央凹中字N+2的预视对汉语阅读眼跳目标选择影响的眼动研究

采用边界范式, 在副中央凹呈现一个双字词或两个单字词, 操纵字N+2的预视(目标预视和假字预视), 来考察副中央凹中词汇特征是否影响读者随后的眼跳长度及注视位置。结果发现, 读者能够获得字N+2的预视; 双字词与两个单字词条件下注视位置没有显著地差异; 当副中央凹中为双字词时, 字N+2为目标预视时随后的眼跳长度显著地长于假字预视条件, 随后的注视位置距离词首更远; 当副中央凹中为两个单字词时, 两种预视条件下随后的眼跳长度及注视位置没有显著的差异。本研究结果提示：在汉语阅读中, 读者能够对字N+2进行预视加工, 这种加工的影响只发生在当副中央凹中为双字词时。     

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.     

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.