Effects of intraword and interword spacing on eye movements during reading: Exploring the optimal use of space in a line of text

Lower-level oculomotor deficits in schizophrenia during multi-line reading: Evidence from return-sweeps

Reading fluency deficits in schizophrenia (Sz) have been attributed to dysfunction in both lower-level, oculomotor processing and higher-level, lexical processing, according to the two-hit deficit model. Given that prior work examining reading deficits in individuals with Sz has primarily focused on single-line and single-word reading tasks, eye movements that are unique to passage reading, such as return-sweep saccades, have not yet been examined in Sz. Return-sweep saccades are large eye movements that are made when readers move from the end of one line to the beginning of the next line during natural passage reading. Examining return-sweeps provides an opportunity to examine lower-level, oculomotor deficits during reading under circumstances when upcoming higher-level, lexical information is not available for visual processing because visual acuity constraints do not permit detailed lexical processing of line-initial words when return-sweeps are programmed. To examine the source of reading deficits in Sz, we analysed an existing data set in which participants read multi-line passages with manipulations to line spacing. Readers with Sz made significantly more return-sweep targeting errors followed by corrective saccades compared with healthy controls. Both groups showed similar effects of line spacing on return-sweep targeting accuracy, suggesting similar sensitivities to visual crowding during reading. Furthermore, the patterns of fixation durations in readers with Sz corroborate prior work indicating reduced parafoveal processing of upcoming words. Together, these findings suggest that lower-level visual and oculomotor dysfunction contribute to reading deficits in Sz, providing support for the two-hit deficit model.

BCLA CLEAR Presbyopia: Evaluation and diagnosis

It is important to be able to measure the range of clear focus in clinical practice to advise on presbyopia correction techniques and to optimise the correction power. Both subjective and objective techniques are necessary: subjective techniques (such as patient reported outcome questionnaires and defocus curves) assess the impact of presbyopia on a patient and how the combination of residual objective accommodation and their natural DoF work for them; objective techniques (such as autorefraction, corneal topography and lens imaging) allow the clinician to understand how well a technique is working optically and whether it is the right choice or how adjustments can be made to optimise performance. Techniques to assess visual performance and adverse effects must be carefully conducted to gain a reliable end-point, considering the target size, contrast and illumination. Objective techniques are generally more reliable, can help to explain unexpected subjective results and imaging can be a powerful communication tool with patients. A clear diagnosis, excluding factors such as binocular vision issues or digital eye strain that can also cause similar symptoms, is critical for the patient to understand and adapt to presbyopia. Some corrective options are more permanent, such as implanted inlays / intraocular lenses or laser refractive surgery, so the optics can be trialled with contact lenses in advance (including differences between the eyes) to better communicate with the patient how the optics will work for them so they can make an informed choice.

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.

Binocular coordination of children with dyslexia and typically developing children in linguistic and non-linguistic tasks: evidence from eye movements

Given the increased evidence suggesting the presence of binocular coordination deficits in dyslexia, investigations of binocular eye movements are beneficial to clarify the underlying causes of reading difficulties. This systematic review aims to (a) synthesize the literature through the examination of binocular coordination in children with dyslexia by describing the normative development of stable binocular control and (b) outline future directions. Boolean expressions in the PubMed search were used to define papers. Following a literature search and selection process, 25 papers were included. Studies using binocular eye tracking during linguistic and nonlinguistic tasks in children with dyslexia and typical development 5-17 years of age are reviewed. The studies reviewed provided consistent evidence of poor binocular coordination in children with dyslexia, but the results associated with different task characteristics were less consistent. The relation between binocular coordination deficits and reading difficulties needs to be further elucidated in longitudinal studies which may provide future treatments targeting the binocular viewing system in dyslexia.

Manipulating Interword and Interletter Spacing in Cursive Script: An Eye Movements Investigation of Reading Persian

Persian is an Indo-Iranian language that features a derivation of Arabic cursive script, where most letters within words are connectable to adjacent letters with ligatures. Two experiments are reported where the properties of Persian script were utilized to investigate the effects of reducing interword spacing and increasing the interletter distance (ligature) within a word. Experiment 1 revealed that decreasing interword spacing while extending interletter ligature by the same amount was detrimental to reading speed. Experiment 2 largely replicated these findings. The experiments show that providing the readers with inaccurate word boundary information is detrimental to reading rate. This was achieved by reducing the interword space that follows letters that do not connect to the next letter in Experiment 1, and replacing the interword space with ligature that connected the words in Experiment 2. In both experiments, readers were able to comprehend the text read, despite the considerable costs to reading rates in the experimental conditions.

Eye-movement control during learning and scanning of Landolt-C stimuli: Exposure frequency effects and spacing effects in a visual search task

We examined whether typical frequency effects observed in normal reading would also occur in a target search task using non-linguistic Landolt-C stimuli. In an initial learning session, we simulated development of frequency effects by controlling exposures participants received of Landolt-C clusters during learning. In a subsequent scanning session, we manipulated the cluster demarcation form of linear strings of Landolt-C clusters (i.e., spaced vs. unspaced vs. shaded unspaced). Participants were required to scan and search for pre-learnt target clusters that were embedded in longer Landolt-C strings. During learning, frequency effects were successfully simulated such that targets with more exposures received shorter fixation time than those with fewer exposures. Participants were unable to successfully detect the pre-learnt targets when they were embedded in the strings during scanning. No evidence of frequency effects was observed in the scanning session. In contrast, eye-movement control was significantly influenced by cluster demarcation form, with increased difficulty for unspaced strings, less for shaded strings, and least for spaced strings. Furthermore, typical landing position distributions that occur in reading of spaced languages also occurred during scanning of spaced Landolt-C strings but not for the shaded or the unspaced strings. In conclusion, exposure frequency effects were successfully simulated during learning but did not carry over to target search during scanning of Landolt-C strings. Possible reasons why frequency effects did not occur in the scanning session are discussed.

Learning Experience Design in Health Professions Education: A Conceptual Review of Evidence for Educators

OBJECTIVES

The increasing use of online resources in emergency medicine (EM) education has driven demand for higher quality resources. Learning experience design (LED) is the study of how electronic user interfaces impact learner outcomes. We sought to summarize the evidence for LED principles to inform creation of EM educational resources.

METHODS

We performed scripted searches of MeSH terms, PubMed keywords, and hand tracings. Inclusion criteria were controlled studies using light-emitting diode or liquid crystal display monitors with Latin-based languages. Cathode ray tube (CRT) monitors were excluded because of the user experience confounders.

RESULTS

Thirty-two articles met inclusion criteria. Overall, 14-point size significantly improved legibility compared to smaller font sizes. Similarly, Verdana and Arial typefaces significantly improved legibility compared to Times New Roman typeface. Verdana also significantly decreased subjective mental workload and visibility difficulty ratings and required the least eye movement of any typefaces tested. Positive polarity (dark text on light background) significantly improved reading outcomes across many measurements over negative polarity. There was higher character identification accuracy with higher luminance. Text effects (e.g., italics), interword and interletter spacing, and page presentation are among variables with mixed or minimal evidence.

CONCLUSION

Learning experience design principles significantly impacted reading and learning outcomes in laboratory settings. No studies evaluated classroom outcomes. Recommendations for electronic learning environments are 14-point font with Verdana or Arial typeface with positive polarity (dark letters on light background). We recommend increasing screen brightness slightly. EM educators may significantly improve the speed and accuracy of learning written material by espousing evidence-based LED principles.

Do readers use character information when programming return-sweep saccades?

Reading saccades that occur within a single line of text are guided by the size of letters. However, readers occasionally need to make longer saccades (known as return-sweeps) that take their eyes from the end of one line of text to the beginning of the next. In this study, we tested whether return-sweep saccades are also guided by font size information and whether this guidance depends on visual acuity of the return-sweep target area. To do this, we manipulated the font size of letters (0.29 vs 0.39° per character) and the length of the first line of text (16 vs 26°). The larger font resulted in return-sweeps that landed further to the right of the line start and in a reduction of under-sweeps compared to the smaller font. This suggests that font size information is used when programming return-sweeps. Return-sweeps in the longer line condition landed further to the right of the line start and the proportion of under-sweeps increased compared to the short line condition. This likely reflects an increase in saccadic undershoot error with the increase in intended saccade size. Critically, there was no interaction between font size and line length. This suggests that when programming return-sweeps, the use of font size information does not depend on visual acuity at the saccade target. Instead, it appears that readers rely on global typographic properties of the text in order to maintain an optimal number of characters to the left of their first fixation on a new line.

Wider Letter-Spacing Facilitates Word Processing but Impairs Reading Rates of Fast Readers

Previous reports of improved oral reading performance for dyslexic children but not for regular readers when between-letter spacing was enlarged led to the proposal of a dyslexia-specific deficit in visual crowding. However, it is in this context also critical to understand how letter spacing affects visual word recognition and reading in unimpaired readers. Adopting an individual differences approach, the present study, accordingly, examined whether wider letter spacing improves reading performance also for non-impaired adults during silent reading and whether there is an association between letter spacing and crowding sensitivity. We report eye movement data of 24 German students who silently read texts presented either with normal or wider letter spacing. Foveal and parafoveal crowding sensitivity were estimated using two independent tests. Wider spacing reduced first fixation durations, gaze durations, and total fixation time for all participants, with slower readers showing stronger effects. However, wider letter spacing also reduced skipping probabilities and elicited more fixations, especially for faster readers. In terms of words read per minute, wider letter spacing did not provide a benefit, and faster readers in particular were slowed down. Neither foveal nor parafoveal crowding sensitivity correlated with the observed letter-spacing effects. In conclusion, wide letter spacing reduces single word processing time in typically developed readers during silent reading, but affects reading rates negatively since more words must be fixated. We tentatively propose that wider letter spacing reinforces serial letter processing in slower readers, but disrupts parallel processing of letter chunks in faster readers. These effects of letter spacing do not seem to be mediated by individual differences in crowding sensitivity.

Visual training could be useful for improving reading capabilities in dyslexia

The term dyslexia originated in 1887 when an ophthalmologist described the difficulty of learning to read. After more than a century of research, we still do not know the etiology of such pathology. Several hypotheses have been suggested to explain dyslexia and in the present article we will describe in detail the visual attentional deficits reported in dyslexia. Reading is a complex cognitive process during which several mechanisms are involved (visual perception, eye movements -saccades and fixations-, semantic and linguistic abilities); consequently, a deficit in one of these different components could cause impairment in reading acquisition. In children with dyslexia, we observed abnormal oculomotor patterns during reading: frequent saccades of small amplitude, long-term fixation, high number of saccades to the left (retro-saccades), and poor binocular coordination during and after the saccades. These results suggest a deficit of visual information processing as well as an immaturity of the interaction between the saccade and vergence systems. In the present review, we will discuss different methods that use short periods of visual rehabilitation or text manipulation, and by using an eye tracker in order to obtain objective information on eye movement's performance during reading, assist in improved reading performance of dyslexic children.

Adult Age Differences in Effects of Text Spacing on Eye Movements During Reading

Large-scale changes in text spacing, such as removing the spaces between words, disrupt reading more for older (65+ years) than younger (18–30 years) adults. However, it is unknown whether older readers show greater sensitivity to simultaneous subtle changes in inter-letter and inter-word spacing encountered in everyday reading. To investigate this, we recorded young and older adults’ eye movements while reading sentences in which inter-letter and inter-word spacing was normal, condensed (10 and 20% smaller than normal), or expanded (10 or 20% larger than normal). Each sentence included either a high or low frequency target word, matched for length and contextual predictability. Condensing but not expanding text spacing disrupted reading more for the older adults. Moreover, word frequency effects (the reading time cost for low compared to high frequency words) were larger for the older adults, consistent with aging effects on lexical processing in previous research. However, this age difference in the word frequency effect did not vary across spacing conditions, suggesting spacing did not further disrupt older readers’ lexical processing. We conclude that visual rather than lexical processing is disrupted more for older readers when text spacing is condensed and discuss this finding in relation to common age-related visual deficits.

Reading sentences of words with rotated letters: An eye movement study

Participants' eye movements were measured as they read sentences in which individual letters within words were rotated. Both the consistency of direction and the magnitude of rotation were manipulated (letters rotated all in the same direction, or alternately clockwise and anti-clockwise, by 30° or 60°). Each sentence included a target word that was manipulated for frequency of occurrence. Our objectives were threefold: To quantify how change in the visual presentation of individual letters disrupted word identification, and whether disruption was consistent with systematic change in visual presentation; to determine whether inconsistent letter transformation caused more disruption than consistent letter transformation; and to determine whether such effects were comparable for words that were high and low frequency to explore the extent to which they were visually or linguistically mediated. We found that disruption to reading was greater as the magnitude of letter rotation increased, although even small rotations affected processing. The data also showed that alternating letter rotations were significantly more disruptive than consistent rotations; this result is consistent with models of lexical identification in which encoding occurs over units of more than one adjacent letter. These rotation manipulations also showed significant interactions with word frequency on the target word: Gaze durations and total fixation duration times increased disproportionately for low-frequency words when they were presented at more extreme rotations. These data provide a first step towards quantifying the relative contribution of the spatial relationships between individual letters to word recognition and eye movement control in reading.

Visual processing during natural reading

Reading is a unique human ability that plays a pivotal role in the development and functioning of our modern society. However, its neural basis remains poorly understood since previous research was focused on reading words with fixed gaze. Here we developed a methodological framework for single-trial analysis of fixation onset-related EEG activity (FOREA) that enabled us to investigate visual information processing during natural reading. To reveal the effect of reading skills on orthographic processing during natural reading, we measured how altering the configural properties of the written text by modifying inter-letter spacing affects FOREA. We found that orthographic processing is reflected in FOREA in three consecutive time windows (120–175 ms, 230–265 ms, 345–380 ms after fixation onset) and the magnitude of FOREA effects in the two later time intervals showed a close association with the participants’ reading speed: FOREA effects were larger in fast than in slow readers. Furthermore, these expertise-driven configural effects were clearly dissociable from the FOREA signatures of visual perceptual processes engaged to handle the increased crowding (155–220 ms) as a result of decreasing letter spacing. Our findings revealed that with increased reading skills orthographic processing becomes more sensitive to the configural properties of the written text.

Does Extra Interletter Spacing Help Text Reading in Skilled Adult Readers?

A number of experiments have shown that, in skilled adult readers, a small increase in interletter spacing speeds up the process of visual word recognition relative to the default settings (i.e., judge faster than judge). The goal of the present experiment was to examine whether this effect can be generalized to a more ecological scenario: text reading. Each participant read two stories (367 words each) taken from a standardized reading test. The stories were presented with the standard interletter spacing or with a small increase in interletter spacing (+1.2 points to default) in a within-subject design. An eyetracker was used to register the participants' eye movements. Comprehension scores were also examined. Results showed that, on average, fixation durations were shorter while reading the text with extra spacing than while reading the text with the default settings (237 vs. 245 ms, respectively; η2 =. 41, p = .01). However, the number of fixations (while nonsignificant) was slightly higher in the text with extra spacing than in the text with the default spacing, and cancelled out the effect of interletter spacing in total reading times (F < 1). Comprehension scores were similar in the two spacing conditions (F < 1). Thus, at least for skilled adult readers, interletter spacing does not seem to play a consistently facilitative role during text reading.

The effects of crowding on eye movement patterns in reading

Crowding is a phenomenon that characterizes normal periphery limiting letter identification when other letters surround the signal. We investigated the nature of the reading limitation of crowding by analyzing eye-movement patterns. The stimuli consisted of two items varying across trials for letter spacing (spaced, unspaced and increased size), lexicality (words or pseudowords), number of letters (4, 6, 8), and reading modality (oral and silent). In Experiments 1 and 2 (oral and silent reading, respectively) the results show that an increase in letter spacing induced an increase in the number of fixations and in gaze duration, but a reduction in the first fixation duration. More importantly, increasing letter size (Experiment 3) produced the same first fixation duration advantage as empty spacing, indicating that, as predicted by crowding, only center-to-center letter distance, and not spacing per se, matters. Moreover, when the letter size was enlarged the number of fixations did not increase as much as in the previous experiments, suggesting that this measure depends on visual acuity rather than on crowding. Finally, gaze duration, a measure of word recognition, did not change with the letter size enlargement. No qualitative differences were found between oral and silent reading experiments (1 and 2), indicating that the articulatory process did not influence the outcome. Finally, a facilitatory effect of lexicality was found in all conditions, indicating an interaction between perceptual and lexical processing. Overall, our results indicate that crowding influences normal word reading by means of an increase in first fixation duration, a measure of word encoding, which we interpret as a modulatory effect of attention on critical spacing.

Can colours be used to segment words when reading?

Rayner, Fischer, and Pollatsek (1998, Vision Research) demonstrated that reading unspaced text in Indo-European languages produces a substantial reading cost in word identification (as deduced from an increased word-frequency effect on target words embedded in the unspaced vs. spaced sentences) and in eye movement guidance (as deduced from landing sites closer to the beginning of the words in unspaced sentences). However, the addition of spaces between words comes with a cost: nearby words may fall outside high-acuity central vision, thus reducing the potential benefits of parafoveal processing. In the present experiment, we introduced a salient visual cue intended to facilitate the process of word segmentation without compromising visual acuity: each alternating word was printed in a different colour (i.e., ). Results only revealed a small reading cost of unspaced alternating colour sentences relative to the spaced sentences. Thus, present data are a demonstration that colour can be useful to segment words for readers of spaced orthographies.

Default spacing is the optimal spacing for word reading

Increased interletter spacing is thought to reduce crowding effects and to enhance fluent reading. Several studies have shown beneficial effects of increased interletter spacing on reading speed and accuracy, especially in poor readers. Therefore, increased interletter spacing appears to be a relatively easy way to enhance reading performance. However, in adult readers reading speed was shown to be impeded with increased interletter spacing. Thus, findings on interletter spacing are still inconclusive. In the current study we examined the effect of a range of interletter spacings (-0.5, default, 0.5, 1, 1.5, 2) on naming fluency of monosyllabic and bisyllabic words in beginning (Grade 2) and more advanced (Grade 4) readers. Additionally we tested the effects of spacing in a subsample of poor readers. In contrast to previous findings, neither beginning nor advanced readers benefited from an increase in interletter spacing. However, they did show reduced reading fluency when letter spacing was smaller than the default spacing, which may be indicative of a crowding effect. Poor readers showed a similar pattern. We conclude that an increase in interletter spacing has no effect on word naming fluency.

Enhanced text spacing improves reading performance in individuals with macular disease

The search by many investigators for a solution to the reading problems encountered by individuals with no central vision has been long and, to date, not very fruitful. Most textual manipulations, including font size, have led to only modest gains in reading speed. Previous work on spatial integrative properties of peripheral retina suggests that ‘visual crowding’ may be a major factor contributing to inefficient reading. Crowding refers to the fact that juxtaposed targets viewed eccentrically may be difficult to identify. The purpose of this study was to assess the combined effects of line spacing and word spacing on the ability of individuals with age-related macular degeneration (ARMD) to read short passages of text that were printed with either high (87.5%) or low contrast (17.5%) letters. Low contrast text was used to avoid potential ceiling effects and to mimic a possible reduction in letter contrast with light scatter from media opacities. For both low and high contrast text, the fastest reading speeds we measured were for passages of text with double line and double word spacing. In comparison with standard single spacing, double word/line spacing increased reading speed by approximately 26% with high contrast text (p < 0.001), and by 46% with low contrast text (p < 0.001). In addition, double line/word spacing more than halved the number of reading errors obtained with single spaced text. We compare our results with previous reading studies on ARMD patients, and conclude that crowding is detrimental to reading and that its effects can be reduced with enhanced text spacing. Spacing is particularly important when the contrast of the text is reduced, as may occur with intraocular light scatter or poor viewing conditions. We recommend that macular disease patients should employ double line spacing and double-character word spacing to maximize their reading efficiency.