Two stages of parafoveal processing during reading: Evidence from a display change detection task

We used a display change detection paradigm (Slattery, Angele, & Rayner Human Perception and Performance, 37, 1924–1938 2011) to investigate whether display change detection uses orthographic regularity and whether detection is affected by the processing difficulty of the word preceding the boundary that triggers the display change. Subjects were significantly more sensitive to display changes when the change was from a nonwordlike preview than when the change was from a wordlike preview, but the preview benefit effect on the target word was not affected by whether the preview was wordlike or nonwordlike. Additionally, we did not find any influence of preboundary word frequency on display change detection performance. Our results suggest that display change detection and lexical processing do not use the same cognitive mechanisms. We propose that parafoveal processing takes place in two stages: an early, orthography-based, preattentional stage, and a late, attention-dependent lexical access stage

Reading sentences of uniform word length II: very rapid adaptation of the preferred saccade length

In the current study we investigated whether readers adjust their preferred saccade length (PSL) during reading on a trial-by-trial basis. The PSL refers to the distance between a saccade launch site and saccade target (i.e., the word center during reading) when participants neither undershoot nor overshoot this target (McConkie, Kerr, Reddix, & Zola, 1988). The tendency for saccades longer or shorter than the PSL to under or overshoot their target is referred to as the range error. Recent research by Cutter, Drieghe, and Liversedge (2017) has shown that the PSL changes to be shorter when readers are presented with thirty consecutive sentences exclusively made of three letter words, and longer when presented with thirty consecutive sentences exclusively made of five letter words. We replicated and extended this work by this time presenting participants with these uniform sentences in an unblocked design. We found that adaptation still occurred across different sentence types despite participants only having one trial to adapt. Our analyses suggested that this effect was driven by the length of the words readers were making saccades away from, rather than the length of the words in the rest of the sentence. We propose an account of the range error in which readers use parafoveal word length information to estimate the length of a saccade between the centre of two parafoveal words (termed the Centre-Based Saccade Length) prior to landing on the first of these words

The programming of sequences of saccades

Saccadic eye movements move the high-resolution fovea to point at regions of interest. Saccades can only be generated serially (i.e., one at a time). However, what remains unclear is the extent to which saccades are programmed in parallel (i.e., a series of such moments can be planned together) and how far ahead such planning occurs. In the current experiment, we investigate this issue with a saccade contingent preview paradigm. Participants were asked to execute saccadic eye movements in response to seven small circles presented on a screen. The extent to which participants were given prior information about target locations was varied on a trial-by-trial basis: participants were aware of the location of the next target only, the next three, five, or all seven targets. The addition of new targets to the display was made during the saccade to the next target in the sequence. The overall time taken to complete the sequence was decreased as more targets were available up to all seven targets. This was a result of a reduction in the number of saccades being executed and a reduction in their saccade latencies. Surprisingly, these results suggest that, when faced with a demand to saccade to a large number of target locations, saccade preparation about all target locations is carried out in paralle

Letter Identity and Position Coding in the Parafovea

Letter position coding has been extensively examined in studies of isolated word identification, spurring the development of computational models. However, these models are largely restricted to explaining word identification in foveal vision despite the fact that early lexical processing during reading occurs in the parafovea. We report four experiments that examined the flexibility of parafoveal letter identity and position coding using a variant of the same-different match task. Participants matched transposed- and substituted-letter strings to reference words, with the former being displayed at various retinal eccentricities for 100 ms versus 300 ms to respectively preclude or allow eye movements. The first pair of experiments demonstrated the relative difficulty of coding parafoveal letter positions as compared to their identities, as well as the standard benefit in identifying words displayed in the right visual field. The second pair of experiments further demonstrated that the location of letter-position uncertainty (i.e., transposed letters) interacts with both eccentricity and visual field. Initial letter transpositions were more easily detected in the left visual field whereas transpositions of the final letters were more accurately detected in the right visual field. As discussed, these results are challenging for existing models of reading which can individually account for some of our findings but not the results in their entirety

Reading during the composition of multi-sentence texts: an eye-movement study

Writers composing multi-sentence texts have immediate access to a visual representation of what they have written. Little is known about the detail of writers’ eye movements within this text during production. We describe two experiments in which competent adult writers’ eye-movements were tracked while performing short expository writing tasks. These are contrasted with conditions in which participants read and evaluated researcher-provided texts. Writers spent a mean of around 13% of their time looking back into their text. Initiation of these look-back sequences was strongly predicted by linguistically important boundaries in their ongoing production (e.g., writers were much more likely to look back immediately prior to starting a new sentence). 36% of look-back sequences were associated with sustained reading and the remainder with less patterned forward and backward saccades between words ("hopping"). Fixation and gaze durations and the presence of word-length effects suggested lexical processing of fixated words in both reading and hopping sequences. Word frequency effects were not present when writers read their own text. Findings demonstrate the technical possibility and potential value of examining writers’ fixations within their just-written text. We suggest that these fixations do not serve solely, or even primarily, in monitoring for error, but play an important role in planning ongoing production

What is the role of the film viewer? The effects of narrative comprehension and viewing task on gaze control in film

Film is ubiquitous, but the processes that guide viewers' attention while viewing film narratives are poorly understood. In fact, many film theorists and practitioners disagree on whether the film stimulus (bottom-up) or the viewer (top-down) is more important in determining how we watch movies. Reading research has shown a strong connection between eye movements and comprehension, and scene perception studies have shown strong effects of viewing tasks on eye movements, but such idiosyncratic top-down control of gaze in film would be anathema to the universal control mainstream filmmakers typically aim for. Thus, in two experiments we tested whether the eye movements and comprehension relationship similarly held in a classic film example, the famous opening scene of Orson Welles' Touch of Evil (Welles & Zugsmith, Touch of Evil, 1958). Comprehension differences were compared with more volitionally controlled task-based effects on eye movements. To investigate the effects of comprehension on eye movements during film viewing, we manipulated viewers' comprehension by starting participants at different points in a film, and then tracked their eyes. Overall, the manipulation created large differences in comprehension, but only produced modest differences in eye movements. To amplify top-down effects on eye movements, a task manipulation was designed to prioritize peripheral scene features: a map task. This task manipulation created large differences in eye movements when compared to participants freely viewing the clip for comprehension. Thus, to allow for strong, volitional top-down control of eye movements in film, task manipulations need to make features that are important to narrative comprehension irrelevant to the viewing task. The evidence provided by this experimental case study suggests that filmmakers' belief in their ability to create systematic gaze behavior across viewers is confirmed, but that this does not indicate universally similar comprehension of the film narrative

The concurrent programming of saccades

Sequences of saccades have been shown to be prepared concurrently however it remains unclear exactly what aspects of those saccades are programmed in parallel. To examine this participants were asked to make one or two target-driven saccades: a reflexive saccade; a voluntary saccade; a reflexive then a voluntary saccade; or vice versa. During the first response the position of a second target was manipulated. The new location of the second saccade target was found to impact on second saccade latencies and second saccade accuracy showing that some aspects of the second saccade program are prepared in parallel with the first. However, differences were found in the specific pattern of effects for each sequence type. These differences fit well within a general framework for saccade control in which a common priority map for saccade control is computed and the influence of saccade programs on one another depends not so much on the types of saccade being produced but rather on the rate at which their programs develop

Self-Consistent Estimation of Mislocated Fixations during Reading

During reading, we generate saccadic eye movements to move words into the center of the visual field for word processing. However, due to systematic and random errors in the oculomotor system, distributions of within-word landing positions are rather broad and show overlapping tails, which suggests that a fraction of fixations is mislocated and falls on words to the left or right of the selected target word. Here we propose a new procedure for the self-consistent estimation of the likelihood of mislocated fixations in normal reading. Our approach is based on iterative computation of the proportions of several types of oculomotor errors, the underlying probabilities for word-targeting, and corrected distributions of landing positions. We found that the average fraction of mislocated fixations ranges from about 10% to more than 30% depending on word length. These results show that fixation probabilities are strongly affected by oculomotor errors