Eye movement control during reading: Effects of word frequency and orthographic familiarity

Word frequency and orthographic familiarity were independently manipulated as readers' eye movements were recorded. Word frequency influenced fixation durations and the probability of word skipping when orthographic familiarity was controlled. These results indicate that lexical processing of words can influence saccade programming (as shown by fixation durations and which words are fixated). Orthographic familiarity, but not word frequency, influenced the duration of prior fixations. These results provide evidence for orthographic, but not lexical, parafoveal-on-foveal effects. Overall, the findings have a crucial implication for models of eye movement control in reading: There must be sufficient time for lexical factors to influence saccade programming before saccade metrics and timing are finalized. The conclusions are critical for the fundamental architecture of models of eye movement control in reading -- namely, how to reconcile long saccade programming times and complex linguistic influences on saccades during reading.     

ICAT: a computational model for the adaptive control of fixation durations

Eye movements depend on cognitive processes related to visual information processing. Much has been learned about the spatial selection of fixation locations, while the principles governing the temporal control (fixation durations) are less clear. Here, we review current theories for the control of fixation durations in tasks like visual search, scanning, scene perception, and reading and propose a new model for the control of fixation durations. We distinguish two local principles from one global principle of control. First, an autonomous saccade timer initiates saccades after random time intervals (local-I). Second, foveal inhibition permits immediate prolongation of fixation durations by ongoing processing (local-II). Third, saccade timing is adaptive, so that the mean timer value depends on task requirements and fixation history (Global). We demonstrate by numerical simulations that our model qualitatively reproduces patterns of mean fixation durations and fixation duration distributions observed in typical experiments. When combined with assumptions of saccade target selection and oculomotor control, the model accounts for both temporal and spatial aspects of eye movement control in two versions of a visual search task. We conclude that the model provides a promising framework for the control of fixation durations in saccadic tasks.     

Oculomotor inhibition of return in normal and mindless reading

Oculomotor inhibition of return (O-IOR) is an increase in saccade latency prior to an eye movement to a recently fixated location, as compared with other locations. To investigate O-IOR in reading, subjects participated in two conditions while their eye movements were recorded: normal reading and mindless reading with words replaced by geometric shapes. We investigated the manifestation of O-IOR in reading and whether it is related to extracting meaning from the text or is an oculomotor phenomenon. The results indicated that fixation durations prior to a saccade returning to the immediately preceding fixated word were longer than those to other words, consistent with O-IOR. Furthermore, fixation durations were longest prior to a saccade that returned the eyes to the specific character position in the word that had previously been fixated and dropped off as the distance between the previously fixated character and landing position increased. This result is consistent with the hypothesis that O-IOR is relatively precise in its application during reading and drops off as a gradient. Both of these results were found for text reading and for mindless reading, suggesting that they are consequences of oculomotor control, and not of language processing. Finally, although these temporal IOR effects were robust, no spatial consequences of IOR were observed: Previously fixated words and characters were as likely to be refixated as new words and characters.     

Saccade generation during reading: Are words necessary?

Most current theories of eye movement control during reading are word based in multiple ways: They assume that saccade onset times result from word‐based processes, and that words are involved in selecting a saccade target. In the current study the role of words was examined by occasionally replacing the text with one of five alternate stimulus patterns for a single fixation during reading, and observing the effects on the time, direction, and length of the saccade that ends that fixation. The onset times of many saccades are unaffected by replacing spaces with random letters, thus removing visible word‐units; also, the effects of this removal on saccade length is not different than that of having space‐delimited nonwords. It does not appear that words play a critical role in generating saccades. The results are compatible with the Competition/Interaction theory of eye movement control during reading (Yang & McConkie, 2001).     

The relationship between eye movements and spatial attention

Most previous studies of the attentional consequences of making saccadic eye movements have used peripheral stimuli to elicit eye movements. It is argued that in the light of evidence showing automatic “capture” of attention by peripheral stimuli, these experiments do not distinguish between attentional effects due to peripheral stimuli and those due to eye movements. In the present study, spatial attention was manipulated by varying the probability that peripheral probe stimuli would appear in different positions, while saccades were directed by a central arrow, enabling the effects of attention and eye movements to be separated. The results showed that the time to react to a peripheral stimulus could be shortened both by advance knowledge of its likely position and, separately, by preparing to make a saccade to that position. When the saccade was directed away from the most likely position of the probe, the targets for attention and eye movements were on opposite sides of the display. In this condition, the effects of preparing to make a saccade proved to be stronger than the effects of attentional allocation until well after the saccade had finished, suggesting that making a saccade necessarily involves the allocation of attention to the target position. The effects of probe stimuli on saccade latencies were also examined: probe stimuli that appeared before the saccade shortened saccade latencies if they appeared at the saccade target, and lengthened saccade latencies if they appeared on the opposite side of fixation. These facilitatory and inhibitory effects were shown to occur at different stages of saccade preparation and suggest that attention plays an important role in the generation of voluntary eye movements. The results of this study indicate that while it is possible to make attention movements without making corresponding eye movements, it is not possible to make an eye movement (in the absence of peripheral stimulation) without making a corresponding shift in the focus of attention.     

How strongly do word reading times and lexical decision times correlate? Combining data from eye movement corpora and megastudies

We assess the amount of shared variance between three measures of visual word recognition latencies: eye movement latencies, lexical decision times, and naming times. After partialling out the effects of word frequency and word length, two well-documented predictors of word recognition latencies, we see that 7–44% of the variance is uniquely shared between lexical decision times and naming times, depending on the frequency range of the words used. A similar analysis of eye movement latencies shows that the percentage of variance they uniquely share either with lexical decision times or with naming times is much lower. It is 5–17% for gaze durations and lexical decision times in studies with target words presented in neutral sentences, but drops to 0.2% for corpus studies in which eye movements to all words are analysed. Correlations between gaze durations and naming latencies are lower still. These findings suggest that processing times in isolated word processing and continuous text reading are affected by specific task demands and presentation format, and that lexical decision times and naming times are not very informative in predicting eye movement latencies in text reading once the effect of word frequency and word length are taken into account. The difference between controlled experiments and natural reading suggests that reading strategies and stimulus materials may determine the degree to which the immediacy-of-processing assumption and the eye–mind assumption apply. Fixation times are more likely to exclusively reflect the lexical processing of the currently fixated word in controlled studies with unpredictable target words rather than in natural reading of sentences or texts.     

Manipulation of stimulus onset delay in reading: evidence for parallel programming of saccades

On-line eye movement recording of 12 subjects who read short stories on a cathode ray tube enabled a test of direct control and preprogramming models of eye movements in reading. Contingent upon eye position, a mask was displayed in place of the letters in central vision after each saccade, delaying the onset of the stimulus in each eye fixation. The duration of the delay was manipulated in fixed or randomized blocks. Although the length of the delay strongly affected the duration of the fixations, there was no difference due to the conditions of delay manipulation, indicating that fixation duration is under direct control. However, not all fixations were lengthened by the period of the delay. Some ended while the mask was still present, suggesting they had been preprogrammed. But these "anticipation" eye movements could not have been completely determined before the fixation was processed because their fixation durations and saccade lengths were affected by the spatial extent of the mask, which varied randomly. Neither preprogramming nor existing serial direct control models of eye guidance can adequately account for these data. Instead, a model with direct control and parallel programming of saccades is proposed to explain the data and eye movements in reading in general.     

Eye movements during repeated reading of a text

The facilitation of eye movements was studied in two experiments involving a repeated reading paradigm. A text was read three times. Initial reading was immediately followed by the first repetition; the second repetition took place one week later. Recall task instructions were used to encourage a detailed reading of the text. The data were analysed sentence by sentence from the 'first pass' readings not including returns to earlier test locations. A general facilitation for all eye movement parameters was found. Repetition decreased the summed fixation time, the average fixation duration, the number of progressive fixations, and the number of regressions. Additionally, repetition increased saccade lengths. Experiment 2 further qualified the general facilitory effect. The middle section of the text, being the most dense of information, was devoted the most visual attention by the readers. Moreover, it was also found to produce the largest degree of facilitation due to repetition. This was true with all other eye movement parameters except saccade length and average fixation duration. Average fixation durations were longer in the beginning of a text than in the end. This was true in all the three readings. Similarly, for each reading, highly important sentences received more visual attention than unimportant sentences.     

英文快速阅读的眼动特点与阅读成绩的关系

该文运用眼动仪对中国大学生在快读阅读英文文本时,其眼动特征与阅读成绩的关系进行了研究。结果表明：在平均注视时间、第一次注视时间、眼跳速度、眼跳次数等方面,高低分组存在显著性差异,高分组的眼动策略更灵活,对信息的加工效率更高。     

Saccade launch site as a predictor of fixation durations in reading: comments on Hand, Miellet, O'Donnell, and Sereno (2010)

An important question in research on eye movements in reading is whether word frequency and word predictability have additive or interactive effects on fixation durations. A fair number of studies have reported only additive effects of the frequency and predictability of a target word on reading times on that word, failing to show significant interactions. Recently, however, Hand, Miellet, O'Donnell, and Sereno (see record 2010-19099-001) reported interactive effects in a study that included the distance of the prior fixation from the target word (launch site). They reported that when the saccade into the target word was launched from very near to the word (within 3 characters), the predictability effect was larger for low frequency words, but when the saccade was launched from a medium distance (4-6 characters from the word) the predictability effect was larger for high frequency words. Hand et al. argued for the importance of including launch site in analyses of target word fixation durations. Here we describe several problems with Hand et al.'s use of analyses of variance in which launch site is divided into distinct ordinal levels. We describe a more appropriate way to analyze such data-linear mixed-effect models-and we use this method to show that launch site does not modulate the interaction between frequency and predictability in two other data sets.     

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.     

Modeling Lag‐2 Revisits to Understand Trade‐Offs in Mixed Control of Fixation Termination During Visual Search

An important question about eye‐movement behavior is when the decision is made to terminate a fixation and program the following saccade. Different approaches have found converging evidence in favor of a mixed‐control account, in which there is some overlap between processing information at fixation and planning the following saccade. We examined one interesting instance of mixed control in visual search: lag‐2 revisits, during which observers fixate a stimulus, move to a different stimulus, and then revisit the first stimulus on the next fixation. Results show that the probability of lag‐2 revisits occurring increased with the number of target‐similar stimuli, and revisits were preceded by a brief fixation on the intervening distractor stimulus. We developed the Efficient Visual Sampling (EVS) computational model to simulate our findings (fixation durations and fixation locations) and to provide insight into mixed control of fixations and the perceptual, cognitive, and motor processes that produce lag‐2 revisits.     

Word frequency in fast priming: Evidence for immediate cognitive control of eye movements during reading

Numerous studies have demonstrated effects of word frequency on eye movements during reading, but the precise timing of this influence has remained unclear. The fast priming paradigm was previously used to study influences of related versus unrelated primes on the target word. Here, we use this procedure to investigate whether the frequency of the prime word has a direct influence on eye movements during reading when the prime–target relation is not manipulated. We found that with average prime intervals of 32 ms readers made longer single fixation durations on the target word in the low than in the high frequency prime condition. Distributional analyses demonstrated that the effect of prime frequency on single fixation durations occurred very early, supporting theories of immediate cognitive control of eye movements. Finding prime frequency effects only 207 ms after visibility of the prime and for prime durations of 32 ms yields new time constraints for cognitive processes controlling eye movements during reading. Our variant of the fast priming paradigm provides a new approach to test early influences of word processing on eye movement control during reading.     

Bottom-up effects modulate saccadic latencies in well-known eye movement paradigm

A well-known eye movement paradigm combines saccades (fast eye movements) with a perceptual discrimination task. At a variable time after the onset of a central arrow cue indicating the target direction [the stimulus onset asynchrony (SOA)], discrimination symbols appear briefly at saccade target and non-target locations. A previous study revealed an unexpected effect of SOA on saccadic latencies: latencies were longer in trials with longer SOAs. It was suggested that this effect reflects a top-down process as observers may wait for the discrimination symbol to appear before executing saccades. However, symbol onsets may also modulate saccade latencies from the bottom-up. To clarify the origin of the SOA effect on latencies in this paradigm, we used a simplified version of the original task plus two new symbol onset conditions for comparison. The results indicate that the modulation of saccadic latencies was not due to a top-down strategy, but to a combination of two opposing bottom-up effects: the symbol onsets at the target location shortened saccade latencies, while symbol onsets at non-target locations lengthened saccade latencies.     

Programming saccadic eye movements

This article addresses questions about the preparatory processes that immediately precede saccadic eye movements. Saccade latencies were measured in a task in which subjects were provided partial advance information about the spatial location of a target fixation. In one experiment, subjects were faster in initiating saccades when they knew either the direction or amplitude of the required movement in advance compared to a condition with equal uncertainty about the number of potential saccade targets but without knowledge of the parameters required to execute the movement. These results suggest that the direction and amplitude for an upcoming saccade were calculated separately, and not in a fixed serial order. In another experiment, subjects appear to have programmed the saccades more holistically--with computations of direction and amplitude parameters occurring simultaneously. The implications of these results for models of eye movement preparation are discussed.     

中文阅读及发展性阅读障碍眼动研究新进展

中文阅读眼动特征的评估参数主要包括注视点停留位置、眼跳、回视和注视时间等。基于眼动技术,并结合生理技术,研究者已揭示出正常读者中文阅读的多方面特点和规律。但对发展性阅读障碍的眼动研究,国内还没有开展起来。从上述两个角度出发,这里总结了正常读者中文阅读的眼动研究,并探讨了发展性阅读障碍者的眼动特征及机制。     

Coarse-to-fine eye movement behavior during visual search

It has previously been argued that, during visual search, eye movement behavior is indicative of an underlying scanning “strategy” that starts on a global, or “coarse,” scale but then progressively focuses to a more local, or “fine,” scale. This conclusion is motivated by the finding that, as a trial progresses, fixation durations tend to increase and saccade amplitudes tend to decrease. In the present study, we replicate these effects but offer an alternative explanation for them—that they emerge from a few stochastic factors that control eye movement behavior. We report the results of a simulation supporting this hypothesis and discuss implications for future models of visual search.     

小学二年级学生汉语阅读知觉广度的眼动研究

小学生阅读知觉广度是阅读发展心理学中的一个基本问题。本研究以Eyelink 1000 plus眼动仪为工具,采用2（年龄）×5（窗口）的两因素混合实验设计,考察小学二年级学生汉语阅读的知觉广度。结果显示,二年级学生的知觉广度为右侧1-2个汉字。二年级小学生快慢读者在眼动指标上存在差异,但未发现在知觉广度上存在差异。阅读能力测验与眼动指标存在显著的相关,此外小学二年级学生的阅读速度可以预测学业成绩。     

双字词整词加工与词素加工在眼跳目标选择中的作用

为探讨整词与词素加工在眼跳目标选择中的作用,本研究采用眼动追踪技术,实验1操纵了目标词的词频（高频、低频）和目标词首字字频（高频、低频）;实验2操纵了目标词的词频（高频、低频）和尾字字频（高频、低频）。结果发现：首字字频不影响眼跳目标选择。尾字字频影响眼跳目标选择,当目标词为低频词时,高频尾字条件下从前目标词到目标词的眼跳长度显著地短于低频字条件;当目标词向前眼跳从尾字发出且目标词为低频词时,高频尾字下的眼跳长度显著地长于低频条件。词频影响眼跳目标选择,高频词条件下跳进和跳出目标词的眼跳长度均长于低频词条件。结果表明整词与尾字词素的加工负荷影响随后的眼跳计划,加工负荷越低随后所计划的眼跳长度越长,尾字词素的加工受整词加工的调节,整词与词素加工以混合表征的方式影响眼动控制。     

The effect of visual complexity and word frequency on eye movements during Chinese reading

Eye movements of native Chinese readers were monitored when they read sentences containing single-character target words orthogonally manipulated for frequency and visual complexity (number of strokes). Both factors yielded strong main effects on skipping probability but no interaction, with readers skipping visually simple and high frequency words more often. However, an interaction between frequency and complexity was observed on the fixation times on the target words with longer fixations for the low frequency, visually complex words. The results demonstrate that visual complexity and frequency have independent influences on saccadic targeting behaviour during Chinese reading but jointly influence fixation durations and that these two factors differently impact fixation durations and saccade targeting during reading.