Eye movements during reading of randomly shuffled text

Auditory distraction during reading: Investigating the effects of background sounds on parafoveal processing

Previous research suggests that unexpected (deviant) sounds negatively affect reading performance by inhibiting saccadic planning, which models of reading agree takes place simultaneous to parafoveal processing. This study examined the effect of deviant sounds on foveal and parafoveal processing. Participants read single sentences in quiet, standard (repeated sounds), or deviant sound conditions (a new sound within a repeated sound sequence). Sounds were presented with a variable delay coincident with the onset of fixations on target words during a period when saccadic programming and parafoveal processing occurred. We used the moving window paradigm to manipulate the amount of information readers could extract from the parafovea (the entire sentence or a 13-character window of text). Global, sentence-level analyses showed typical disruption to reading by the window, and under quiet conditions similar effects were observed at the target and post-target word in the local analyses. Standard and deviant sounds also produced clear distraction effects of differing magnitudes at the target and post-target words, though at both regions, these effects were qualified by interactions. Effects at the target word suggested that with sounds, readers engaged in less effective parafoveal processing than under quiet. Similar patterns of effects due to standard and deviant sounds, each with a different time course, occurred at the post-target word. We conclude that distraction via auditory deviation causes disruption to parafoveal processing during reading, with such effects being modulated by the degree to which a sound's characteristics are more or less unique.

Eye-tracking as a proxy for coherence and complexity of texts

Reading is a complex cognitive process that involves primary oculomotor function and high-level activities like attention focus and language processing. When we read, our eyes move by primary physiological functions while responding to language-processing demands. In fact, the eyes perform discontinuous twofold movements, namely, successive long jumps (saccades) interposed by small steps (fixations) in which the gaze “scans” confined locations. It is only through the fixations that information is effectively captured for brain processing. Since individuals can express similar as well as entirely different opinions about a given text, it is therefore expected that the form, content and style of a text could induce different eye-movement patterns among people. A question that naturally arises is whether these individuals’ behaviours are correlated, so that eye-tracking while reading can be used as a proxy for text subjective properties. Here we perform a set of eye-tracking experiments with a group of individuals reading different types of texts, including children stories, random word generated texts and excerpts from literature work. In parallel, an extensive Internet survey was conducted for categorizing these texts in terms of their complexity and coherence, considering a large number of individuals selected according to different ages, gender and levels of education. The computational analysis of the fixation maps obtained from the gaze trajectories of the subjects for a given text reveals that the average “magnetization” of the fixation configurations correlates strongly with their complexity observed in the survey. Moreover, we perform a thermodynamic analysis using the Maximum-Entropy Model and find that coherent texts were closer to their corresponding “critical points” than non-coherent ones, as computed from the Pairwise Maximum-Entropy method, suggesting that different texts may induce distinct cohesive reading activities.

Eye movements during text reading align with the rate of speech production

Across languages, the speech signal is characterized by a predominant modulation of the amplitude spectrum between about 4.3 and 5.5 Hz, reflecting the production and processing of linguistic information chunks (syllables and words) every ~200 ms. Interestingly, ~200 ms is also the typical duration of eye fixations during reading. Prompted by this observation, we demonstrate that German readers sample written text at ~5 Hz. A subsequent meta-analysis of 142 studies from 14 languages replicates this result and shows that sampling frequencies vary across languages between 3.9 Hz and 5.2 Hz. This variation systematically depends on the complexity of the writing systems (character-based versus alphabetic systems and orthographic transparency). Finally, we empirically demonstrate a positive correlation between speech spectrum and eye movement sampling in low-skilled non-native readers, with tentative evidence from post hoc analysis suggesting the same relationship in low-skilled native readers. On the basis of this convergent evidence, we propose that during reading, our brain's linguistic processing systems imprint a preferred processing rate-that is, the rate of spoken language production and perception-onto the oculomotor system.

The influence of foveal lexical processing load on parafoveal preview and saccadic targeting during Chinese reading

Whether increased foveal load causes a reduction of parafoveal processing remains equivocal. The present study examined foveal load effects on parafoveal processing in natural Chinese reading. Parafoveal preview of a single-character parafoveal target word was manipulated by using the boundary paradigm (Rayner, 1975; pseudocharacter or identity previews) under high foveal load (low-frequency pretarget word) compared with low foveal load (high-frequency pretarget word) conditions. Despite an effective manipulation of foveal processing load, we obtained no evidence of any modulatory influence on parafoveal processing in first-pass reading times. However, our results clearly showed that saccadic targeting, in relation to forward saccade length from the pretarget word and in relation to target word skipping, was influenced by foveal load and this influence occurred independent of parafoveal preview. Given the optimal experimental conditions, these results provide very strong evidence that preview benefit is not modulated by foveal lexical load during Chinese reading.

The findings of the present study show that foveal processing load, as manipulated through lexical frequency, has no modulatory influence on preview benefit for the subsequent word in a sentence during natural Chinese reading. Foveal processing difficulty does, however, influence saccades that determine where the eyes fixate next, and this influence occurs regardless of preview benefit for the following word. These results pertain directly to the Foveal Load Hypothesis that has received significant scrutiny in recent years. They also directly inform current understanding of the complexities of the relationship between the oculomotor control system that is responsible for positioning the point of fixation during reading and the complex cognitive processes that occur during written Chinese language comprehension.

Reading without spaces revisited: The role of word identification and sentence-level constraints

The present study examined the relative contribution of bottom-up word identification and top-down sentence-level constraints in facilitating the reading of text printed without between-word spacing. We compared reading of grammatically correct sentences and shuffled versions of the same words presented both with normal spacing and without spaces. We found that reading was hampered by removing sentence structure as well as by removing spaces. A significantly greater impact of sentence structure when reading unspaced text was found in probe word identification accuracies and total viewing times per word, whereas the impact of sentence structure on the probability of making a regressive eye movement was greater when reading normally spaced text. Crucially, we also found that the length of the currently fixated word determined the amplitude of forward saccades leaving that word during the reading of unspaced text. We conclude that the relative ease with which skilled readers can read unspaced text is due to a combination of an increased use of bottom-up word identification in guiding the timing and targeting of eye movements, plus an increased interactivity between word identification and sentence-level processing.

Reading without spaces: The role of precise letter order

Prior research points to efficient identification of embedded words as a key factor in facilitating the reading of text printed without spacing between words. Here we further tested the primary role of bottom-up word identification by altering this process with a letter transposition manipulation. In two experiments, we examined silent reading and reading aloud of normal sentences and sentences containing words with letter transpositions, in both normally spaced and unspaced conditions. We predicted that letter transpositions should be particularly harmful for reading unspaced text. In line with our prediction, the majority of our measures of reading fluency showed that unspaced text with letter transpositions was disproportionately difficult to read. These findings provide further support for the claim that reading text without between-word spacing relies principally on efficient bottom-up processing, enabling accurate word identification in the absence of visual cues to identify word boundaries.

Parafoveal previews and lexical frequency in natural reading: Evidence from eye movements and fixation-related potentials

Participants' eye movements and electroencephalogram (EEG) signal were recorded as they read sentences displayed according to the gaze-contingent boundary paradigm. Two target words in each sentence were manipulated for lexical frequency (high vs. low frequency) and parafoveal preview of each target word (identical vs. string of random letters vs. string of Xs). Eye movement data revealed visual parafoveal-on-foveal (PoF) effects, as well as foveal visual and orthographic preview effects and word frequency effects. Fixation-related potentials (FRPs) showed visual and orthographic PoF effects as well as foveal visual and orthographic preview effects. Our results replicated the early preview positivity effect (Dimigen, Kliegl, & Sommer, 2012) in the X-string preview condition, and revealed different neural correlates associated with a preview comprised of a string of random letters relative to a string of Xs. The former effects seem likely to reflect difficulty associated with the integration of parafoveal and foveal information, as well as feature overlap, while the latter reflect inhibition, and potentially disruption, to processing underlying reading. Interestingly, and consistent with Kretzschmar, Schlesewsky, and Staub (2015), no frequency effect was reflected in the FRP measures. The findings provide insight into the neural correlates of parafoveal processing and written word recognition in reading and demonstrate the value of utilizing ecologically valid paradigms to study well established phenomena that occur as text is read naturally. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Fixation durations in scene viewing: Modeling the effects of local image features, oculomotor parameters, and task

Scene perception requires the orchestration of image- and task-related processes with oculomotor constraints. The present study was designed to investigate how these factors influence how long the eyes remain fixated on a given location. Linear mixed models (LMMs) were used to test whether local image statistics (including luminance, luminance contrast, edge density, visual clutter, and the number of homogeneous segments), calculated for 1° circular regions around fixation locations, modulate fixation durations, and how these effects depend on task-related control. Fixation durations and locations were recorded from 72 participants, each viewing 135 scenes under three different viewing instructions (memorization, preference judgment, and search). Along with the image-related predictors, the LMMs simultaneously considered a number of oculomotor and spatiotemporal covariates, including the amplitudes of the previous and next saccades, and viewing time. As a key finding, the local image features around the current fixation predicted this fixation’s duration. For instance, greater luminance was associated with shorter fixation durations. Such immediacy effects were found for all three viewing tasks. Moreover, in the memorization and preference tasks, some evidence for successor effects emerged, such that some image characteristics of the upcoming location influenced how long the eyes stayed at the current location. In contrast, in the search task, scene processing was not distributed across fixation durations within the visual span. The LMM-based framework of analysis, applied to the control of fixation durations in scenes, suggests important constraints for models of scene perception and search, and for visual attention in general.

Evidence for a global oculomotor program in reading

Recent corpus studies of eye-movements in reading revealed a substantial increase in saccade amplitudes and fixation durations as the eyes move over the first words of a sentence. This start-up effect suggests a global oculomotor program, which operates on the level of an entire line, in addition to the well-established local programs operating within the visual span. The present study investigates the nature of this global program experimentally and examines whether the start-up effect is predicated on generic visual or specific linguistic characteristics and whether it is mainly reflected in saccade amplitudes, fixation durations or both measures. Eye movements were recorded while 38 participants read (a) normal sentences, (b) sequences of randomly shuffled words and (c) sequences of z-strings. The stimuli were, therefore, similar in their visual features, but varied in the amount of syntactic and lexical information. Further, the stimuli were composed of words or strings that either varied naturally in length (Nonequal condition) or were all restricted to a specific length within a sentence (Equal). The latter condition constrained the variability of saccades and served to dissociate effects of word position in line on saccade amplitudes and fixation durations. A robust start-up effect emerged in saccade amplitudes in all Nonequal stimuli, and-in an attenuated form-in Equal sentences. A start-up effect in single fixation durations was observed in Nonequal and Equal normal sentences, but not in z-strings. These findings support the notion of a global oculomotor program in reading particularly for the spatial characteristics of motor planning, which rely on visual rather than linguistic information.

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.

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.

Reading strategy modulates parafoveal-on-foveal effects in sentence reading

Task demands and individual differences have been linked reliably to word skipping during reading. Such differences in fixation probability may imply a selection effect for multivariate analyses of eye-movement corpora if selection effects correlate with word properties of skipped words. For example, with fewer fixations on short and highly frequent words the power to detect parafoveal-on-foveal effects is reduced. We demonstrate that increasing the fixation probability on function words with a manipulation of the expected difficulty and frequency of questions reduces an age difference in skipping probability (i.e., old adults become comparable to young adults) and helps to uncover significant parafoveal-on-foveal effects in this group of old adults. We discuss implications for the comparison of results of eye-movement research based on multivariate analysis of corpus data with those from display-contingent manipulations of target words.

Effects of load on the time course of attentional engagement, disengagement, and orienting in reading

We examined how the frequency of the fixated word influences the spatiotemporal distribution of covert attention during reading. Participants discriminated gaze-contingent probes that occurred with different spatial and temporal offsets from randomly chosen fixation points during reading. We found that attention was initially focused at fixation and that subsequent defocusing was slower when the fixated word was lower in frequency. Later in a fixation, attention oriented more towards the next saccadic target for high- than for low-frequency words. These results constitute the first report of the time course of the effect of load on attentional engagement and orienting in reading. They are discussed in the context of serial and parallel models of reading.

Using E-Z reader to examine word skipping during reading

The question of why readers sometimes skip words has important theoretical implications for our understanding of perception, cognition, and oculomotor control during reading (Drieghe, Rayner, & Pollatsek, 2005). In this article, the E-Z Reader model of eye-movement control in reading (Reichle, 2011) was used to examine the behavioral consequences of word skipping on fixation durations. The simulations suggest that skipping "cost," or inflated fixation durations immediately prior to skips, is modulated by the lexical properties of the upcoming word (i.e., longer fixations before skipping infrequent and/or long words; Kliegl & Engbert, 2005) but that contrary to previous claims (e.g., Reichle & Laurent, 2006), "accidental" skips due to motor error also produce skipping cost. In contrast, the cost associated with having skipped a word was not modulated by that word's properties. These simulations suggest that skipping behavior is even more complicated than previously has been assumed and that further empirical research is needed to understand the causal link between skipping and its associated cost.

Your mind wanders weakly, your mind wanders deeply: objective measures reveal mindless reading at different levels

When the mind wanders, attention turns away from the external environment and cognitive processing is decoupled from perceptual information. Mind wandering is usually treated as a dichotomy (dichotomy-hypothesis), and is often measured using self-reports. Here, we propose the levels of inattention hypothesis, which postulates attentional decoupling to graded degrees at different hierarchical levels of cognitive processing. To measure graded levels of attentional decoupling during reading we introduce the sustained attention to stimulus task (SAST), which is based on psychophysics of error detection. Under experimental conditions likely to induce mind wandering, we found that subjects were less likely to notice errors that required high-level processing for their detection as opposed to errors that only required low-level processing. Eye tracking revealed that before errors were overlooked influences of high- and low-level linguistic variables on eye fixations were reduced in a graded fashion, indicating episodes of mindless reading at weak and deep levels. Individual fixation durations predicted overlooking of lexical errors 5s before they occurred. Our findings support the levels of inattention hypothesis and suggest that different levels of mindless reading can be measured behaviorally in the SAST. Using eye tracking to detect mind wandering online represents a promising approach for the development of new techniques to study mind wandering and to ameliorate its negative consequences.

The zoom lens of attention: Simulating shuffled versus normal text reading using the SWIFT model

Assumptions on the allocation of attention during reading are crucial for theoretical models of eye guidance. The zoom lens model of attention postulates that attentional deployment can vary from a sharp focus to a broad window. The model is closely related to the foveal load hypothesis, i.e., the assumption that the perceptual span is modulated by the difficulty of the fixated word. However, these important theoretical concepts for cognitive research have not been tested quantitatively in eye movement models. Here we show that the zoom lens model, implemented in the SWIFT model of saccade generation, captures many important patterns of eye movements. We compared the model's performance to experimental data from normal and shuffled text reading. Our results demonstrate that the zoom lens of attention might be an important concept for eye movement control in reading.