Simulated cataract does not reduce the benefit of RSVP

Simulation of visual impairment in persons with normal vision for scientific research

Simulation of visual impairment in healthy eyes has multiple applications in students' training, research and product development. However, due to the absence of an existing standard protocol, the method of simulation was left to the discretion of the researcher. This review aimed to outline the various methods of simulating visual impairment and categorising them. A scoping review of the relevant publications was conducted. Of the 1593 articles originally retrieved from the databases, 103 were included in the review. The characteristics of the participants, the method for simulation of the visual impairment in persons with normal vision and the level or type of visual impairment that was simulated were extracted from the papers. None of the methods of simulation can be judged as being superior to the others. However, electronic displays produced the most consistent form of visual impairment simulation.

Assessing reading performance in the periphery with a Bayesian adaptive approach: The qReading method

Reading is a crucial visual activity and a fundamental skill in daily life. Rapid Serial Visual Presentation (RSVP) is a text-presentation paradigm that has been extensively used in the laboratory to study basic characteristics of reading performance. However, measuring reading function (reading speed vs. print size) is time-consuming for RSVP reading using conventional testing procedures. In this study, we develop a novel method, qReading, utilizing the Bayesian adaptive testing framework to measure reading function in the periphery. We perform both a psychophysical experiment and computer simulations to validate the qReading method. In the experiment, words are presented using an RSVP paradigm at 10° in the lower visual field. The reading function obtained from the qReading method with 50 trials exhibits good agreement (i.e., high accuracy) with the reading function obtained from a conventional method (method of constant stimuli [MCS]) with 186 trials (mean root mean square error: 0.12 log10 units). Simulations further confirm that the qReading method provides an unbiased measure. The qReading procedure also demonstrates excellent precision (half width of 68.2% credible interval: 0.02 log10 units with 50 trials) compared to the MCS method (0.03 log10 units with 186 trials). This investigation establishes that the qReading method can adequately measure the reading function in the normal periphery with high accuracy, precision, and efficiency, and is a potentially valuable tool for both research and clinical assessments.

Blur Adaptation to Central Retinal Disease

Purpose

The long-term, low-resolution vision experienced by individuals affected by retinal disease that causes central vision loss (CVL) may change their perception of blur through adaptation. This study used a short-term adaptation paradigm to evaluate adaptation to blur and sharpness in patients with CVL.

Methods

A variation of Webster's procedure was used to measure the point of subjective neutrality (PSN). The image that appeared normal after adaptation to each of seven blur and sharpness levels (PSN) was measured in 12 patients with CVL (20/60 to 20/320) and 5 subjects with normal sight (NS). Patients with CVL used a preferred retinal locus to view the images. Small control studies investigated the effects of long-term and medium-term (1 hour) defocus and diffusive blur.

Results

Adaptation was reliably measured in patients with CVL and in the peripheral vision of NS subjects. The shape of adaptation curves was similar in patients with CVL and both central and peripheral vision of NS subjects. No statistical correlations were found between adaptation and age, visual acuity, retinal eccentricity, or contrast sensitivity. Long-term blur experience by a non-CVL myopic participant caused a shift in the adaptation function. Conversely, medium-term adaptation did not cause a shift in the adaptation function.

Conclusions

Blur and sharp short-term adaptation occurred in peripheral vision of normal and diseased retinas. In most patients with CVL, neither adaptation nor blur perception was affected by long-term attention to peripheral low-resolution vision. The impact of blur/sharp adaptation on the benefit of image enhancement techniques for patients with CVL is discussed.

Perceptual and Cognitive Factors Imposing "Speed Limits" on Reading Rate: A Study with the Rapid Serial Visual Presentation

Adults read at high speed, but estimates of their reading rate vary greatly, i.e., from 100 to 1500 words per minute (wpm). This discrepancy is likely due to different recording methods and to the different perceptual and cognitive processes involved in specific test conditions. The present study investigated the origins of these notable differences in RSVP reading rate (RR). In six experiments we investigated the role of many different perceptual and cognitive variables. The presence of a mask caused a steep decline in reading rate, with an estimated masking cost of about 200 wpm. When the decoding process was isolated, RR approached values of 1200 wpm. When the number of stimuli exceeded the short-term memory span, RR decreased to 800 wpm. The semantic context contributed to reading speed only by a factor of 1.4. Finally, eye movements imposed an upper limit on RR (around 300 wpm). Overall, data indicate a speed limit of 300 wpm, which corresponds to the time needed for eye movement execution, i.e., the most time consuming mechanism. Results reconcile differences in reading rates reported by different laboratories and thus provide suggestions for targeting different components of reading rate.

Bringing text display digital radio to consumers with hearing loss

Radio is migrating to digital transmission, expanding its offerings to include captioning for individuals with hearing loss. Text display radio requires a large amount of word throughput with minimal screen display area, making good user interface design crucial to its success. In two experiments, we presented hearing, hard-of-hearing, and deaf consumers with National Public Radio stories converted to text and examined their preferences for and reactions to midsized and small radio text displays. We focused on physical display attributes such as text color, font style, line length, and scrolling type as well as emergency alert messages and emergency prompts for drivers, announcer identification schemes, and synchronization of audio and text. Results suggest that midsized, Global Positioning System (GPS)-style displays were well liked, synchronization of audio and text was important to comprehension and retrieval of story details, identification of announcers was served best with a combination of name change in parenthesis and color change, and a mixture of color and flashing symbols was preferred for emergency alerting.

Beating the beat: reading can be faster than the frequency of eye movements in persons with congenital nystagmus

PURPOSE

Rapid serial visual presentation (RSVP) of text has been reported to foster higher reading rates than presentation in a continuous text (CT) format, possibly because scanning eye movements are minimized. We investigated how this might be relevant for persons with congenital nystagmus (CN).

METHODS

We evaluated whether reading rates differ in persons with CN for RSVP versus CT presentation of single sentences under otherwise similar conditions. In a second experiment, we presented unrelated words to observers with CN in RSVP format while measuring their eye movements to determine whether reading can occur during the high-velocity, nonfoveating periods of the CN wave form. Both sentences and random words were selected from the MNRead corpus and displayed at 2x, 4x, or 8x the threshold word size on a 21-inch computer monitor.

RESULTS

Subjects with CN have virtually equivalent maximum reading speeds of 449 and 448 words per minute, respectively, for RSVP and CT presentation of sentences. Typically, reading rates were faster than the frequency of CN, which suggests that subjects could read during the nonfoveating periods of the nystagmus waveform. This finding was confirmed using random words that, unlike those in sentences, cannot be inferred from contextual cues. Examination of eye movements recorded during reading indicated that random words are read correctly with 47% to 65% accuracy (depending on word size) during the nonfoveating periods of the CN waveform.

CONCLUSION

A clinical implication of these results is that reading performance in persons with CN should be facilitated by large text sizes that remain legible during a greater fraction of the CN waveform.

Low-vision reading speed: influences of linguistic inference and aging

PURPOSE

Reading is a dynamic task involving both linguistic and visual analysis. In this study, we asked how two types of linguistic information--characters used in segmenting words from one another, and sentence context--differ in their usefulness for people with normal and low vision. Given evidence for age-related differences in some forms of cognitive processing, we also investigated the effect of age.

METHODS

There were four groups of 10 participants: vision status (normal, low) crossed with age (young, <35 years; old, >65 years). Reading speeds were compared for regularly spaced text and text in which the spaces were removed, a manipulation intended to eliminate local cues for text segmentation and force attention to clusters of letters or whole words. We also evaluated the effect of sentence context by comparing reading speeds for regular sentences and sentences in which word order was scrambled.

RESULTS

Removal of spaces had a greater impact on low vision than normal vision, reducing average speeds to 45% and 66% of speeds for regularly spaced text, respectively. We interpret this to mean that people with low vision have less access to spatially distributed linguistic regularities of text such as prefixes, suffixes, or word length. Removal of sentence context through scrambling had a greater impact on normal vision than low vision, reducing mean reading speed to 53% and 66%, respectively. Finally, comparison of our young and old readers showed no major differences in the use of sentence context or in the impact of removing spaces between words.

CONCLUSIONS

People with low vision appear to rely more on spacing information in sentences, whereas people with normal vision appear to make better use of sentence context, irrespective of age.

Dynamic Chinese text on a single-line display: effects of presentation mode

There are many technologies with which users must read text from small-screen electronic devices. So, understanding the constraints and optimization of humans' use of these devices is important. In the present study, the optimal ways to display Chinese text on a single-line display were explored. 64 Chinese-speaking Taiwanese undergraduates participated in a 4x2 mixed design in which the presentation mode was a between-subjects factor and the text difficulty was a within-subjects factor. Four presentation modes in which two presentation formats, i.e., leading and rapid serial visual presentation, combined with two text layouts, i.e., convention and Interword spacing, were investigated. Chinese texts of High Difficulty and Low Difficulty were compared. The results showed that the leading format with Interword spacing resulted in greater reading efficiency and faster preferred reading speed than other presentation modes. Although the reading efficiency and preferred reading speed for Low Difficulty materials were significantly greater than for High Difficulty materials, the interaction between the presentation mode and text difficulty was not significant. The applications for presenting moving Chinese text on a single-line display are briefly discussed.