Eye tracking: empirical foundations for a minimal reporting guideline.

In this paper, we present a review of how the various aspects of any study using an eye tracker (such as the instrument, methodology, environment, participant, etc.) affect the quality of the recorded eye-tracking data and the obtained eye-movement and gaze measures. We take this review to represent the empirical foundation for reporting guidelines of any study involving an eye tracker. We compare this empirical foundation to five existing reporting guidelines and to a database of 207 published eye-tracking studies. We find that reporting guidelines vary substantially and do not match with actual reporting practices. We end by deriving a minimal, flexible reporting guideline based on empirical research (Section "An empirically based minimal reporting guideline").

Parafoveal processing and transposed-letter effects in dyslexic reading.

During parafoveal processing, skilled readers encode letter identity independently of letter position (Johnson et al., 2007). In the current experiment, we examined orthographic parafoveal processing in readers with dyslexia. Specifically, the eye movements of skilled readers and adult readers with dyslexia were recorded during a boundary paradigm experiment (Rayner, 1975). Parafoveal previews were either identical to the target word (e.g., nearly), a transposed-letter preview (e.g., enarly), or a substituted-letter preview (e.g., acarly). Dyslexic and non-dyslexic readers demonstrated orthographic parafoveal preview benefits during silent sentence reading and both reading groups encoded letter identity and letter position information parafoveally. However, dyslexic adults showed, that very early in lexical processing, during parafoveal preview, the positional information of a word's initial letters were encoded less flexibly compared to during skilled adult reading. We suggest that dyslexic readers are less able to benefit from correct letter identity information (i.e., in the letter transposition previews) due to the lack of direct mapping of orthography to phonology. The current findings demonstrate that dyslexic readers show consistent and dyslexic-specific reading difficulties in foveal and parafoveal processing during silent sentence reading.

Presenting GECO: An eyetracking corpus of monolingual and bilingual sentence reading.

This article introduces GECO, the Ghent Eye-Tracking Corpus, a monolingual and bilingual corpus of the eyetracking data of participants reading a complete novel. English monolinguals and Dutch-English bilinguals read an entire novel, which was presented in paragraphs on the screen. The bilinguals read half of the novel in their first language, and the other half in their second language. In this article, we describe the distributions and descriptive statistics of the most important reading time measures for the two groups of participants. This large eyetracking corpus is perfectly suited for both exploratory purposes and more directed hypothesis testing, and it can guide the formulation of ideas and theories about naturalistic reading processes in a meaningful context. Most importantly, this corpus has the potential to evaluate the generalizability of monolingual and bilingual language theories and models to the reading of long texts and narratives. The corpus is freely available at http://expsy.ugent.be/downloads/geco .

The jingle fallacy in comprehension tests for reading.

The Jingle fallacy is the false assumption that instruments which share the same name measure the same underlying construct. In this experiment, we focus on the comprehension subtests of the Nelson Denny Reading Test (NDRT) and the Wechsler Individual Achievement Test (WIAT-II). 91 university students read passages for comprehension whilst their eye movements were recorded. Participants took part in two experimental blocks of which the order was counterbalanced, one with higher comprehension demands and one with lower comprehension demands. We assumed that tests measuring comprehension would be able to predict differences observed in eye movement patterns as a function of varying comprehension demands. Overall, readers were able to adapt their reading strategy to read more slowly, making more and longer fixations, coupled with shorter saccades when comprehension demands were higher. Within an experimental block, high scorers on the NDRT were able to consistently increase their pace of reading over time for both higher and lower comprehension demands, whereas low scorers approached a threshold where they could not continue to increase their reading speed or further reduce the number of fixations to read a text, even when comprehension demands were low. Individual differences based on the WIAT-II did not explain similar patterns. The NDRT comprehension test was therefore more predictive of differences in the reading patterns of skilled adult readers in response to comprehension demands than the WIAT-II (which also suffered from low reliability). Our results revealed that these different comprehension measures should not be used interchangeably, and researchers should be cautious when choosing reading comprehension tests for research.

Individual differences and the transposed letter effect during reading.

When a preview contains substituted letters (SL; markey) word identification is more disrupted for a target word (monkey), compared to when the preview contains transposed letters (TL; mnokey). The transposed letter effect demonstrates that letter positions are encoded more flexibly than letter identities, and is a robust finding in adults. However, letter position encoding has been shown to gradually become more flexible as reading skills develop. It is unclear whether letter position encoding flexibility reaches maturation in skilled adult readers, or whether some differences in the magnitude of the TL effect remain in relation to individual differences in cognitive skills. We examined 100 skilled adult readers who read sentences containing a correct, TL or SL preview. Previews were replaced by the correct target word when the reader's gaze triggered an invisible boundary. Cognitive skills were assessed and grouped based on overlapping variance via Principal Components Analysis (PCA) and subsequently used to predict eye movement measures for each condition. Consistent with previous literature, adult readers were found to generally encode letter position more flexibly than letter identity. Very few differences were found in the magnitude of TL effects between adults based on individual differences in cognitive skills. The flexibility of letter position encoding appears to reach maturation (or near maturation) in skilled adult readers.

Individual differences in word skipping during reading in English as L2.

The Multilingual Eye-movement Corpus (MECO; Siegelman et al., 2022) contains data from unbalanced bilinguals reading in their first language (L1) for a variety of languages and in English as their second language (L2). We analyzed word skipping in L2 on the basis of five predictors consisting of the frequency and length of the word in L2 and three measures of individual differences. Besides the L2 proficiency of the participant, two novel measures were also constructed: the average amount of skipping in L1 across participants per language and whether an individual reader skips words often in their L1 compared with other L1 readers in the same language. Word skipping in L2 increased for short and high-frequency words, for participants with higher L2 proficiency, for readers whose L1 featured relatively high average skipping rates compared with the other languages, and especially for participants who skip more often in L1 than their peers. All three individual differences interacted with word length such that their influence was more pronounced for longer words. Our results show that readers prefer to maintain a certain level of word skipping resembling how they read in L1. Due to lower L2 than L1 proficiency in unbalanced bilinguals, word skipping in L2 would often be based on a comparatively less advanced stage in parafoveal word recognition.

The role of visual crowding in eye movements during reading: Effects of text spacing.

Visual crowding, generally defined as the deleterious influence of clutter on visual discrimination, is a form of inhibitory interaction between nearby objects. While the role of crowding in reading has been established in psychophysics research using rapid serial visual presentation (RSVP) paradigms, how crowding affects additional processes involved in natural reading, including parafoveal processing and saccade targeting, remains unclear. The current study investigated crowding effects on reading via two eye-tracking experiments. Experiment 1 was a sentence-reading experiment incorporating an eye-contingent boundary change in which reader's parafoveal processing was quantified through comparing reading times after valid or invalid information was presented in the parafovea. Letter spacing was jointly manipulated to compare how crowding affects parafoveal processing. Experiment 2 was a passage-reading experiment with a line spacing manipulation. In addition to replicating previously observed letter spacing effects on global reading parameters (i.e., more but shorter fixations with wider spacing), Experiment 1 found an interaction between preview validity and letter spacing indicating that the efficiency of parafoveal processing was constrained by crowding and visual acuity. Experiment 2 found reliable but subtle influences of line spacing. Participants had shorter fixation durations, higher skipping probabilities, and less accurate return sweeps when line spacing was increased. In addition to extending the literature on the role of crowding to reading in ecologically valid scenarios, the current results inform future research on characterizing the influence of crowding in natural reading and comparing effects of crowding across reader populations.

Beyond isolated word recognition.

In this commentary we concur with Frost's view of the centrality of universal principles in models of word identification. However, we argue that other processes in sentence comprehension also fundamentally constrain the nature of written word identification. Furthermore, these processes appear to be universal. We, therefore, argue that universality in word identification should not be considered in isolation, but instead in the context of other linguistic processes that occur during normal reading.

Parafoveal processing of repeated words during reading.

In an eye-tracking experiment during reading, we examined the repetition effect, whereby words that are repeated in the same paragraph receive shorter fixation durations. Target words that were either high-frequency or low-frequency words and of which the parafoveal preview was either correct or with all letters replaced were embedded three times in the same paragraph. Shorter fixation times and higher skipping rates were observed for high-frequency compared to low-frequency words, words for which the parafoveal preview was correct versus incorrect, and as the word was being repeated more often. An interaction between frequency and repetition indicated that the reduction in fixation times due to repetition was more pronounced for low-frequency words. We also observed influences of word repetition on parafoveal processing, as repeated words were skipped more often. An interaction between parafoveal preview and repetition indicated an absent repetition effect when the preview was incorrect, but this effect was short lived, as it was restricted to the first fixation duration on the target word.

The impact of hyperlinks, skim reading and perceived importance when reading on the Web.

It has previously been shown that readers spend a great deal of time skim reading on the Web and that this type of reading can affect comprehension of text. Across two experiments, we examine how hyperlinks influence perceived importance of sentences and how perceived importance in turn affects reading behaviour. In Experiment 1, participants rated the importance of sentences across passages of Wikipedia text. In Experiment 2, a different set of participants read these passages while their eye movements were tracked, with the task being either reading for comprehension or skim reading. Reading times of sentences were analysed in relation to the type of task and the importance ratings from Experiment 1. Results from Experiment 1 show readers rated sentences without hyperlinks as being of less importance than sentences that did feature hyperlinks, and this effect is larger when sentences are lower on the page. It was also found that short sentences with more links were rated as more important, but only when they were presented at the top of the page. Long sentences with more links were rated as more important regardless of their position on the page. In Experiment 2, higher importance scores resulted in longer sentence reading times, measured as fixation durations. When skim reading, however, importance ratings had a lesser impact on online reading behaviour than when reading for comprehension. We suggest readers are less able to establish the importance of a sentence when skim reading, even though importance could have been assessed by information that would be fairly easy to extract (i.e. presence of hyperlinks, length of sentences, and position on the screen).

Does diacritics-based lexical disambiguation modulate word frequency, length, and predictability effects? An eye-movements investigation of processing Arabic diacritics.

In Arabic, a predominantly consonantal script that features a high incidence of lexical ambiguity (heterophonic homographs), glyph-like marks called diacritics supply vowel information that clarifies how each consonant should be pronounced, and thereby disambiguate the pronunciation of consonantal strings. Diacritics are typically omitted from print except in situations where a particular homograph is not sufficiently disambiguated by the surrounding context. In three experiments we investigated whether the presence of disambiguating diacritics on target homographs modulates word frequency, length, and predictability effects during reading. In all experiments, the subordinate representation of the target homographs was instantiated by the diacritics (in the diacritized conditions), and by the context subsequent to the target homographs. The results replicated the effects of word frequency (Experiment 1), word length (Experiment 2), and predictability (Experiment 3). However, there was no evidence that diacritics-based disambiguation modulated these effects in the current study. Rather, diacritized targets in all experiments attracted longer first pass and later (go past and/or total fixation count) processing. These costs are suggested to be a manifestation of the subordinate bias effect. Furthermore, in all experiments, the diacritics-based disambiguation facilitated later sentence processing, relative to when the diacritics were absent. The reported findings expand existing knowledge about processing of diacritics, their contribution towards lexical ambiguity resolution, and sentence processing.

The impact of skim reading and navigation when reading hyperlinks on the web.

It has been shown that readers spend a great deal of time skim reading on the Web and that this type of reading can affect lexical processing of words. Across two experiments, we utilised eye tracking methodology to explore how hyperlinks and navigating webpages affect reading behaviour. In Experiment 1, participants read static Webpages either for comprehension or whilst skim reading, while in Experiment 2, participants additionally read through a navigable Web environment. Embedded target words were either hyperlinks or not and were either high-frequency or low-frequency words. Results from Experiment 1 show that while readers lexically process both linked and unlinked words when reading for comprehension, readers only fully lexically process linked words when skim reading, as was evidenced by a frequency effect that was absent for the unlinked words. They did fully lexically process both linked and unlinked words when reading for comprehension. In Experiment 2, which allowed for navigating, readers only fully lexically processed linked words compared to unlinked words, regardless of whether they were skim reading or reading for comprehension. We suggest that readers engage in an efficient reading strategy where they attempt to minimise comprehension loss while maintaining a high reading speed. Readers use hyperlinks as markers to suggest important information and use them to navigate through the text in an efficient and effective way. The task of reading on the Web causes readers to lexically process words in a markedly different way from typical reading experiments.

The impact of hyperlinks on reading text.

There has been debate about whether blue hyperlinks on the Web cause disruption to reading. A series of eye tracking experiments were conducted to explore if coloured words in black text had any impact on reading behaviour outside and inside a Web environment. Experiment 1 and 2 explored the saliency of coloured words embedded in single sentences and the impact on reading behaviour. In Experiment 3, the effects of coloured words/hyperlinks in passages of text in a Web-like environment was explored. Experiment 1 and 2 showed that multiple coloured words in text had no negative impact on reading behaviour. However, if the sentence featured only a single coloured word, a reduction in skipping rates was observed. This suggests that the visual saliency associated with a single coloured word may signal to the reader that the word is important, whereas this signalling is reduced when multiple words are coloured. In Experiment 3, when reading passages of text containing hyperlinks in a Web environment, participants showed a tendency to re-read sentences that contained hyperlinked, uncommon words compared to hyperlinked, common words. Hyperlinks highlight important information and suggest additional content, which for more difficult concepts, invites rereading of the preceding text.

The influence of number of syllables on word skipping during reading revisited.

Fitzsimmons and Drieghe (Psychonomic Bulletin & Review, 18, 736-741, 2011) showed that a monosyllabic word was skipped more often than a disyllabic word during reading. This finding was interpreted as evidence that syllabic information was extracted from the parafovea early enough to influence word skipping. In the present, large-scale replication of this study, in which we additionally measured the reading, vocabulary, and spelling abilities of the participants, the effect of number of syllables on word skipping was not significant. Moreover, a Bayesian analysis indicated strong evidence for the absence of the effect. The individual differences analyses replicate previous observations showing that spelling ability uniquely predicts word skipping (but not fixation times) because better spellers skip more often. The results indicate that high-quality lexical representations allow the system to reach an advanced stage in the word-recognition process of the parafoveal word early enough to influence the decision of whether or not to skip the word, but this decision is not influenced by number of syllables.

Orthographic and root frequency effects in Arabic: Evidence from eye movements and lexical decision.

One of the more studied and robust effects in the reading literature is that of word frequency. Semitic words (e.g., in Arabic or Hebrew) contain roots that indicate the core meaning to which the word belongs. The effects of the frequency of these roots on reading as measured by eye movements is much less understood. In a series of experiments, we investigated and replicated traditional word frequency effects in Arabic: Eye movement measures showed the expected facilitation for high- over low-frequency target words embedded in sentences (Experiment 1). The same was found in response time and accuracy in a lexical-decision task (Experiment 3a). Using target words that were matched on overall orthographic frequency and other important variables but that contained either high- or low-frequency roots, we found no significant influence of root frequency on eye movement measures during sentence reading (Experiment 2). Using the same target words in a lexical-decision task (Experiment 3b), we replicated the absence of root frequency effects on real Arabic word processing. At 1st glance, the results may not appear to be in line with theoretical accounts that postulate early morphological decomposition and root identification when processing Semitic words. However, these results are compatible with accounts where morphological decomposition does occur but is followed by recombination, and under certain conditions recombination costs can eliminate or even reverse root frequency effects. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Eye-movement evidence for the mental representation of strokes in Chinese characters.

Although strokes are the smallest identifiable units in Chinese words, the fact that they are often embedded within larger units (i.e., radicals and/or characters that comprise Chinese words) raises questions about how and even if strokes are separately represented in lexical memory. The present experiment examined these questions using a gaze-contingent boundary paradigm (Rayner, 1975) to manipulate the parafoveal preview of the first of two-character target words. Relative to a normal preview, the removal of whole strokes was more disruptive (i.e., resulting in longer looking times on targets) than the removal of an equivalent amount of visual information (i.e., number of pixels) from strokes located either in similar locations or throughout the entire character. These findings suggest that strokes are represented as discrete functional units rather than visual features or integral parts of the radicals/characters in which they are embedded. We discuss the theoretical implications of this conclusion for models of Chinese word identification. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The word grouping hypothesis and eye movements during reading.

The distribution of landing positions and durations of first fixations in a region containing a noun preceded by either an article (e.g., the soldiers) or a high-frequency 3-letter word (e.g., all soldiers) were compared. Although there were fewer first fixations on the blank space between the high-frequency 3-letter word and the noun than on the surrounding letters (and the fixations on the blank space were shorter), this pattern did not occur when the noun was preceded by an article. R. Radach (1996) inferred from a similar experiment that did not manipulate the type of short word that 2 words could be processed as a perceptual unit during reading when the first word is a short word. As this different pattern of fixations is restricted to article-noun pairs, it indicates that word grouping does not occur purely on the basis of word length during reading; moreover, as the authors demonstrate, one can explain the observed patterns in both conditions more parsimoniously without adopting a word-grouping mechanism in eye movement control during reading.