Reading Speed In Peripheral Vision Research Articles

Effects of Temporal Modulation on Crowding, Visual Span, and Reading

Crowding, the increased difficulty in recognizing a target due to the proximity of adjacent objects, is identified as the main sensory constraint for the size of the visual span (the number of letters recognized without moving the eyes) and reading speed in peripheral vision. The goal of the present study is to assess the impact of temporal modulation on crowding, visual span, and reading in the periphery. Six normally sighted young adults participated in the study. Four temporal modulation patterns were examined: (1) moving scotoma (sequentially masking the component letters in a letter string or word), (2) moving window (sequentially presenting the component letters), (3) flashing (repeatedly masking and presenting all letters simultaneously), and (4) static (the control condition; no temporal changes during the presentation). For each condition, we obtained the spatial extent of crowding, the size of the visual span, and reading speeds measured by the rapid serial visual presentation method. Compared with the static condition, the spatial extent of crowding was reduced in the moving window condition. Both the moving window and moving scotoma conditions led to a faster reading speed for print sizes smaller than critical print size (the smallest print size that allows maximum reading speed). However, none of the temporal modulations increased the size of the visual span and reading speed for print sizes larger than critical print size. The results suggest that the temporal modulation patterns are of limited benefit for peripheral reading despite the substantial improvement for slow reading when print size is close to acuity threshold.

Training as Part of a Word Game Increases Reading Speed in Peripheral Vision

Training as Part of a Word Game Increases Reading Speed in Peripheral Vision

Reading Speed in Peripheral Vision Improves with Practice: Investigation of the Involved Cortical Sites

Reading speed in peripheral vision improves with practice, but the cortical site of this improvement is not understood. Using psychophysics and fMRI, we investigated the potential training-related functional changes in retinotopic and non-retinotopic cortical areas. Ten young normally sighted subjects were trained (1hour/day over 4days) to read sentences displayed in the lower visual field (10º eccentricity) using the Rapid Serial Visual Presentation (RSVP) paradigm. Pre- and post-training psychophysical tests included RSVP reading speed, visual span and orientation discrimination (Gabor patch) measurements in both the trained (lower) and untrained (upper) visual fields. Functional MRI measurements (BOLD) were recorded before and after training for eccentric RSVP reading (at four presentation rates) and grating orientation discrimination. The fMRI measurements used a rapid event-related design, with analysis focusing on three cortical regions: the primary visual cortex, Broca’s area and the visual word form area (VWFA). Training resulted in a significant gain (60% ±25%) in RSVP reading speed in the trained visual field, and partial transfer of this improvement to the untrained upper visual field. The fMRI results showed that the activity level in VWFA was dependent on the presentation rate and in turn was positively correlated with the percentage of words accurately recognized. More specifically, before training, BOLD activity in VWFA was significantly weaker (p<0.01) for the fastest (hardest) reading condition than for the slowest (easiest) one, but this difference was significantly reduced after training. A weaker but similar trend was observed in retinotopic cortex as well. Our results show that VWFA response during reading in peripheral vision is affected by a training protocol that enhances reading speed. The more uniform VWFA responses at the four RSVP rates following training may be associated with higher word recognition accuracy for the faster rates which in turn yield shallower behavioral psychometric functions. Meeting abstract presented at VSS 2013

Reading Speed in Peripheral Vision Improves with Practice: Investigation of the Involved Cortical Sites

Reading Speed in Peripheral Vision Improves with Practice: Investigation of the Involved Cortical Sites

Sensory and cognitive influences on the training-related improvement of reading speed in peripheral vision

Reading speed in normal peripheral vision is slow but can be increased through training on a letter-recognition task. The aim of the present study is to investigate the sensory and cognitive factors responsible for this improvement. The visual span is hypothesized to be a sensory bottleneck limiting reading speed. Three sensory factors-letter acuity, crowding, and mislocations (errors in the spatial order of letters)-may limit the size of the visual span. Reading speed is also influenced by cognitive factors including the utilization of information from sentence context. We conducted a perceptual training experiment to investigate the roles of these factors. Training consisted of four daily sessions of trigram letter-recognition trials at 10° in the lower visual field. Subjects' visual-span profiles and reading speeds were measured in pre- and posttests. Effects of the three sensory factors were isolated through a decomposition analysis of the visual span profiles. The impact of sentence context was indexed by context gain, the ratio of reading speeds for ordered and unordered text. Following training, visual spans increased in size by 5.4 bits of information transmitted, and reading speeds increased by 45%. Training induced a substantial reduction in the magnitude of crowding (4.8 bits) and a smaller reduction for mislocations (0.7 bits), but no change in letter acuity or context gain. These results indicate that the basis of the training-related improvement in reading speed is a large reduction in the interfering effect of crowding and a small reduction of mislocation errors.

Improving Reading Speed in Peripheral Vision with Perceptual Learning: A Behavioral and fMRI Investigation

Improving Reading Speed in Peripheral Vision with Perceptual Learning: A Behavioral and fMRI Investigation

The mechanism of word crowding

Word reading speed in peripheral vision is slower when words are in close proximity of other words ( Chung, 2004). This word crowding effect could arise as a consequence of interaction of low-level letter features between words, or the interaction between high-level holistic representations of words. We evaluated these two hypotheses by examining how word crowding changes for five configurations of flanking words: the control condition – flanking words were oriented upright; scrambled – letters in each flanking word were scrambled in order; horizontal-flip – each flanking word was the left–right mirror-image of the original; letter-flip – each letter of the flanking word was the left–right mirror-image of the original; and vertical-flip – each flanking word was the up–down mirror-image of the original. The low-level letter feature interaction hypothesis predicts similar word crowding effect for all the different flanker configurations, while the high-level holistic representation hypothesis predicts less word crowding effect for all the alternative flanker conditions, compared with the control condition. We found that oral reading speed for words flanked above and below by other words, measured at 10° eccentricity in the nasal field, showed the same dependence on the vertical separation between the target and its flanking words, for the various flanker configurations. The result was also similar when we rotated the flanking words by 90° to disrupt the periodic vertical pattern, which presumably is the main structure in words. The remarkably similar word crowding effect irrespective of the flanker configurations suggests that word crowding arises as a consequence of interactions of low-level letter features.

Oculo-motor patterns induced by reading in peripheral vision

There is clear evidence that slower reading in peripheral vision results from shrinkage of the visual span - the number of letters recognized with high accuracy without moving the eyes. Based on this evidence, an ideal-observer model, Mr. Chips (Legge et al., 2002), has been used to simulate saccade planning in reading. This model shows a strong relationship between the size of the visual span and saccade length. One prediction of this model is that reading speed in peripheral vision should be correlated with the saccade length (or more precisely with the horizontal component's length of saccades). This prediction is based on the implicit assumption that regression saccades do not occur too often. We have investigated this issue by measuring eye movements of 34 patients with central field loss (induced by age-related macular degeneration). Patients had to read aloud 14 French sentences displayed in succession (each sentence was displayed on one line). Character size was 3× the individual ETDRS acuity. Each patient had an absolute macular scotoma covering the fovea as assessed by MP1 microperimetry. Ocular data were collected with an Eyelink II eyetracker (500 Hz). The horizontal distribution of fixations was analyzed for each sentence with kernel density estimates. In addition, we assessed whether these distributions contained regions with statistically significant curvature – i.e., regions with a high density of fixations (called clusters hereafter). Results show a high variability of density estimates both within- and between patients: some sentences exhibit very homogeneous distributions while others show clear density peaks. The main finding is that reading speed is significantly slower for sentences that contain fixation clusters compared to sentences without clusters. This relationship between reading speed and the presence of fixation clusters has to our knowledge never been reported and should be taken into account to understand eccentric reading.

The mechanism of word crowding

Word reading speed in peripheral vision is slower when words are in close proximity of other words (Chung, 2004). This word crowding effect could arise as a consequence of interaction of low-level letter features between words, or the interaction between high-level holistic representations of words. We evaluated these two hypotheses by examining how word crowding changes for five configurations of flanking words: the control condition - flanking words were oriented upright; scrambled - letters in each flanking word were scrambled in order; horizontal-flip - each flanking word was the left-right mirror-image of the original; letter-flip - each letter of the flanking word was the left-right mirror-image of the original; and vertical-flip - each flanking word was the up-down mirror-image of the original. The low-level letter feature interaction hypothesis predicts similar word crowding effect for all the different flanker configurations, while the high-level holistic representation hypothesis predicts less word crowding effect for all the alternative flanker conditions, compared with the control condition. We found that oral reading speed for words flanked above and below by other words, measured at 10° eccentricity in the nasal field, showed the same dependence on the vertical separation between the target and its flanking words, for the various flanker configurations. The result was also similar when we rotated the flanking words by 90° to disrupt the periodic vertical pattern, which presumably is the main structure in words. The remarkably similar word crowding effect irrespective of the flanker configurations suggests that word crowding arises as a consequence of interactions of low-level letter features.

Training improves reading speed in peripheral vision: Is it due to attention?

Previous research has shown that perceptual training in peripheral vision, using a letter-recognition task, increases reading speed and letter recognition (S. T. L. Chung, G. E. Legge, & S. H. Cheung, 2004). We tested the hypothesis that enhanced deployment of spatial attention to peripheral vision explains this training effect. Subjects were pre- and post-tested with 3 tasks at 10° above and below fixation-RSVP reading speed, trigram letter recognition (used to construct visual-span profiles), and deployment of spatial attention (measured as the benefit of a pre-cue for target position in a lexical-decision task). Groups of five normally sighted young adults received 4 days of trigram letter-recognition training in upper or lower visual fields, or central vision. A control group received no training. Our measure of deployment of spatial attention revealed visual-field anisotropies; better deployment of attention in the lower field than the upper, and in the lower-right quadrant compared with the other three quadrants. All subject groups exhibited slight improvement in deployment of spatial attention to peripheral vision in the post-test, but this improvement was not correlated with training-related increases in reading speed and the size of visual-span profiles. Our results indicate that improved deployment of spatial attention to peripheral vision does not account for improved reading speed and letter recognition in peripheral vision.

Letter-recognition and reading speed in peripheral vision benefit from perceptual learning

Visual-span profiles are plots of letter-recognition accuracy as a function of letter position left or right of the midline. Previously, we have shown that contraction of these profiles in peripheral vision can account for slow reading speed in peripheral vision. In this study, we asked two questions: (1) can we modify visual-span profiles through training on letter-recognition, and if so, (2) are these changes accompanied by changes in reading speed? Eighteen normally sighted observers were randomly assigned to one of three groups: training at 10° in the upper visual field, training at 10° in the lower visual field and a no-training control group. We compared observers’ characteristics of reading (maximum reading speed and critical print size) and visual-span profiles (peak amplitude and bits of information transmitted) before and after training, and at trained and untrained retinal locations (10° upper and lower visual fields). Reading speeds were measured for six print sizes at each retinal location, using the rapid serial visual presentation paradigm. Visual-span profiles were measured using a trigram letter-recognition task, for a letter size equivalent to 1.4× the critical print size for reading. Training consisted of the repeated measurement of 20 visual-span profiles (over four consecutive days) in either the upper or lower visual field. We also tracked the changes in performance in a sub-group of observers for up to three months following training. We found that the visual-span profiles can be expanded (bits of information transmitted increased by 6 bits) through training with a letter-recognition task, and that there is an accompanying increase (41%) in the maximum reading speed. These improvements transferred, to a large extent, from the trained to an untrained retinal location, and were retained, to a large extent, for at least three months following training. Our results are consistent with the view that the visual span is a bottleneck on reading speed, but a bottleneck that can be increased with practice.