Development and validation of a questionnaire for assessing visual and auditory spatial localization abilities in dual sensory impairment.

Spatial localization is important for social interaction and safe mobility, and relies heavily on vision and hearing. While people with vision or hearing impairment compensate with their intact sense, people with dual sensory impairment (DSI) may require rehabilitation strategies that take both impairments into account. There is currently no tool for assessing the joint effect of vision and hearing impairment on spatial localization in this large and increasing population. To this end, we developed a novel Dual Sensory Spatial Localization Questionnaire (DS-SLQ) that consists of 35 everyday spatial localization tasks. The DS-SLQ asks participants about their difficulty completing different tasks using only vision or hearing, as well as the primary sense they rely on for each task. We administered the DS-SLQ to 104 participants with heterogenous vision and hearing status. Rasch analysis confirmed the psychometric validity of the DS-SLQ and the feasibility of comparing vision and hearing spatial abilities in a unified framework. Vision and hearing impairment were associated with decreased visual and auditory spatial abilities. Differences between vision and hearing abilities predicted overall sensory reliance patterns. In DSI rehabilitation, DS-SLQ may be useful for measuring vision and hearing spatial localization abilities and predicting the better sense for completing different spatial localization tasks.

Visual Impairment and Real-World Home Physical Activity With Home Environment in an Older Population.

Importance: Physical activity levels are lower in visual impairment. However, additional factors, such as home environmental features, which can modify physical activity in this group, are unknown. Objective: To investigate the association between home environment features and home physical activity in patients with visual impairment. Design, Setting, and Participants: This cross-sectional study of clinical patients included participants with glaucoma suspect and primary glaucoma who were 60 years or older with varying degrees of visual field damage. Study participants were recruited from the Johns Hopkins Wilmer Eye Institute Glaucoma Clinic, Baltimore, Maryland, from September 2013 through March 2015. Data were analyzed from December 19, 2022, through December 25, 2022. Main Outcomes and Measures: Total in-home steps taken per day was the primary outcome measure; time in daily home physical activity and nonsedentary activity were secondary outcomes. Results: A total of 153 participants were included in analyses with mean age of 71 (SD, 7.8) years and 71 were female (46%). Sixty percent had more than 1 comorbid illness, about one-third took 5 or more prescription drugs, and median daily home steps were 1137. Median integrated visual field sensitivity was 28 dB. Better-eye median visual acuity in logMAR was 0.05 (20/22 Snellen equivalent). For every 0.1-log unit increment in average measured home lighting, participants took 5% more daily steps (rate ratio [RR], 1.05; 95% CI, 1.00-1.10; P = .04) and had a 3% faster average daily peak cadence (RR, 1.03; 95% CI, 1.01-1.05; P = .01). The average number of nonsedentary activity minutes (RR, 1.04; 95% CI, 1.00-1.07; P = .06), average bout duration (ß = 0.03; 95% CI, 0.00-.07; P = .06), and activity fragmentation (ß = -0.06; 95% CI, -0.13 to 0.00; P = .06) showed associations with home lighting. The number of hazards was not associated with any activity metric (steps: RR, 1.14; 95% CI, 0.96-1.34; P = .13; peak cadence: RR, 1.00; 95% CI, 0.93-1.08; P = .98; and nonsedentary time: RR, 1.11; 95% CI, 0.98-1.26; P = .11), nor was the frequency of hazards. Conclusions and Relevance: In this study, results demonstrated that home environment features, particularly lighting, may influence home activity metrics in older adults with visual impairment. Further prospective studies would be needed to confirm if home modifications can improve at-home activity.

Dual Sensory Impairment: Impact of Central Vision Loss and Hearing Loss on Visual and Auditory Localization.

Purpose: In the United States, AMD is a leading cause of low vision that leads to central vision loss and has a high co-occurrence with hearing loss. The impact of central vision loss on the daily functioning of older individuals cannot be fully addressed without considering their hearing status. We investigated the impact of combined central vision loss and hearing loss on spatial localization, an ability critical for social interactions and navigation. Methods: Sixteen older adults with central vision loss primarily due to AMD, with or without co-occurring hearing loss, completed a spatial perimetry task in which they verbally reported the directions of visual or auditory targets. Auditory testing was done with eyes open in a dimly lit room or with a blindfold. Twenty-three normally sighted, age-matched, and hearing-matched control subjects also completed the task. Results: Subjects with central vision loss missed visual targets more often. They showed increased deviations in visual biases from control subjects as the scotoma size increased. However, these deficits did not generalize to sound localization. As hearing loss became more severe, the sound localization variability increased, and this relationship was not altered by coexisting central vision loss. For both control and central vision loss subjects, sound localization was less reliable when subjects wore blindfolds, possibly due to the absence of visual contextual cues. Conclusions: Although central vision loss impairs visual localization, it does not impair sound localization and does not prevent vision from providing useful contextual cues for sound localization.

Colorimetric Chemosensor Based on Fe3O4 Magnetic Molecularly Imprinted Nanoparticles for Highly Selective and Sensitive Detection of Norfloxacin in Milk.

Long-term use of norfloxacin (NOR) will cause NOR residues in foods and harm human bodies. The determination of NOR residues is important for guaranteeing food safety. In this study, a simple, selective, and label-free colorimetric chemosensor for in situ NOR detection was developed based on Fe3O4 magnetic molecularly imprinted nanoparticles (Fe3O4 MMIP NPs). The Fe3O4 MMIP NPs showed good peroxidase-like catalytic activity to 3,3',5,5'-tetramethylbenzidine (TMB) and selective adsorption ability to NOR. The colorimetric chemosensor was constructed based on the Fe3O4 MMIP NPs-H2O2-TMB reaction system. The absorbance differences were proportional to the concentrations of NOR in the range of 10-300 ng/mL with a limit of detection at 9 ng/mL. The colorimetric chemosensor was successfully applied to detect NOR residue in milk. The recovery range was 78.2-95.81%, with a relative standard deviation of 2.1-9.88%. Together, the proposed colorimetric chemosensor provides a reliable strategy for the detection of NOR residues in foods.

A supramodal and conceptual representation of subsecond time revealed with perceptual learning of temporal interval discrimination.

Subsecond time perception has been frequently attributed to modality-specific timing mechanisms that would predict no cross-modal transfer of temporal perceptual learning. In fact, perceptual learning of temporal interval discrimination (TID) reportedly shows either no cross-modal transfer, or asymmetric transfer from audition to vision, but not vice versa. However, here we demonstrate complete cross-modal transfer of auditory and visual TID learning using a double training paradigm. Specifically, visual TID learning transfers to and optimizes auditory TID when the participants also receive exposure to the auditory temporal interval by practicing a functionally orthogonal near-threshold tone frequency discrimination task at the same trained interval. Auditory TID learning also transfers to and optimizes visual TID with additional practice of an orthogonal near-threshold visual contrast discrimination task at the same trained interval. Practicing these functionally orthogonal tasks per se has no impact on TID thresholds. We interpret the transfer results as indications of a supramodal representation of subsecond time. Moreover, because TID learning shows complete transfer between modalities with vastly different temporal precisions, the sub-second time presentation must be conceptual. Double training may refine this supramodal and conceptual subsecond time representation and connect it to a new sense to improve time perception.

Digital Reading with Low Vision: Principles for Selecting Display Size.

SIGNIFICANCE: Digital reading devices have become increasingly popular among people with low vision. Because displays come in many sizes ranging from smart watches to large desktop computer displays, it is important to have principles to guide people with low vision in selecting suitable displays for reading. PURPOSE: The selection of effective digital displays for reading by people with low vision focuses attention on the interacting effects of print size, display size, font, visual acuity, and reading distance. This technical report aims to provide principles for identifying the minimum size of digital displays required for fluent reading by people with low vision. METHODS: We emphasize two critical factors in selecting an appropriate reading display: angular print size, which should exceed the individual's critical print size, and display size, which should allow at least 13 characters to be presented on each line. Our approach considers a low-vision individual's acuity and preferences for viewing distance and fonts. RESULTS: Through an illustrative example, we demonstrate how our approach can be used to determine display size for a low-vision individual with 20/200 acuity and central field loss who wants to read at 30-cm viewing distance with the Times Roman font. We have developed a web application based on our recommended approach to provide easy access to our algorithm. CONCLUSIONS: We provide a procedure to guide the selection of appropriate displays for a wide range of acuities. Our approach can help clinicians in making recommendations for their patients, digital product designers in developing more accessible devices, and low-vision individuals in selecting digital displays for reading.

Visual and Auditory Spatial Localization in Younger and Older Adults.

Visual and auditory localization abilities are crucial in real-life tasks such as navigation and social interaction. Aging is frequently accompanied by vision and hearing loss, affecting spatial localization. The purpose of the current study is to elucidate the effect of typical aging on spatial localization and to establish a baseline for older individuals with pathological sensory impairment. Using a verbal report paradigm, we investigated how typical aging affects visual and auditory localization performance, the reliance on vision during sound localization, and sensory integration strategies when localizing audiovisual targets. Fifteen younger adults (N = 15, mean age = 26 years) and thirteen older adults (N = 13, mean age = 68 years) participated in this study, all with age-adjusted normal vision and hearing based on clinical standards. There were significant localization differences between younger and older adults, with the older group missing peripheral visual stimuli at significantly higher rates, localizing central stimuli as more peripheral, and being less precise in localizing sounds from central locations when compared to younger subjects. Both groups localized auditory targets better when the test space was visible compared to auditory localization when blindfolded. The two groups also exhibited similar patterns of audiovisual integration, showing optimal integration in central locations that was consistent with a Maximum-Likelihood Estimation model, but non-optimal integration in peripheral locations. These findings suggest that, despite the age-related changes in auditory and visual localization, the interactions between vision and hearing are largely preserved in older individuals without pathological sensory impairments.

Synthesis, characterization and absorption evaluation of bifunctional monomer magnetic molecularly imprinted polymers nanoparticles for the extraction of 6-benzylaminopurine from vegetables.

An adsorbent-magnetic molecularly imprinted polymers nanoparticles (MMIPs NPs) were synthesized for the extraction of 6-benzylaminopurine (6-BA) using Fe3O4 as magnetic core. The MIPs were prepared with methacrylic acid and sodium p-styrene sulfonate as bifunctional monomers. The adsorbents were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometer, thermogravimetric analysis and vibrating sample magnetometer. The adsorption properties were evaluated by static, kinetic and selective adsorption experiments. The MMIPs NPs exhibit a high adsorption capacity (37.63 mg g-1) and favorable imprinting factor (2.88) toward 6-BA. The chromatogram of 6-BA extraction using the MMIPs NPs as the adsorbent demonstrates that the matrix interference has been minimized. More importantly, MMIPs NPs can be applied to extracting 6-BA from mung bean sprout and cucumber with satisfactory recoveries (91.14-104.52%), and can be reused for at least five times. This work provides a new strategy to efficiently extract 6-BA from vegetables.

A Unified Rule for Binocular Contrast Summation Applies to Normal Vision and Common Eye Diseases.

Purpose: Binocular summation refers to better visual performance with two eyes than with one eye. Little is known about the mechanism underlying binocular contrast summation in patients with common eye diseases who often exhibit binocularly asymmetric vision loss and structural changes along the visual pathway. Here we asked whether the mechanism of binocular contrast summation remains preserved in eye disease. Methods: This study included 1035 subjects with normal ocular health, cataract, age-related macular degeneration, glaucoma, and retinitis pigmentosa. Monocular and binocular contrast sensitivity were measured by the Pelli-Robson contrast sensitivity chart. Interocular ratio (IOR) was quantified as the ratio between the poorer and better eye contrast sensitivity. Binocular summation ratio (BSR) was quantified as the ratio between binocular and better eye contrast sensitivity. Results: All groups showed statistically significant binocular summation, with the BSR ranging from 1.25 [1.20, 1.30] in the glaucoma group to 1.31 [1.27, 1.36] in the normal vision group. There was no significant group difference in the BSR, after accounting for IOR. By fitting a binocular summation model Binocular = (Leftm + Rightm)1/m to the contrast sensitivity data, we found that the same binocular summation rule, reflected by the parameter m, applies across the five groups. Conclusions: Cortical binocular contrast summation appears to be preserved in spite of eye diseases that can affect the two eyes differently. This finding supports the importance of assessing both monocular and binocular functions, rather than relying on a monocular assessment in the better eye as a potentially inaccurate surrogate measure.

Simulating Visibility and Reading Performance in Low Vision.

PURPOSE: Low vision reduces text visibility and causes difficulties in reading. A valid low-vision simulation could be used to evaluate the accessibility of digital text for readers with low vision. We examined the validity of a digital simulation for replicating the text visibility and reading performance of low-vision individuals. METHODS: Low-vision visibility was modeled with contrast sensitivity functions (CSFs) with parameters to represent reduced acuity and contrast sensitivity. Digital filtering incorporating these CSFs were applied to digital versions of the Lighthouse Letter Acuity Chart and the Pelli-Robson Contrast Sensitivity Chart. Reading performance (reading acuity, critical print size, and maximum reading speed) was assessed with filtered versions of the MNREAD reading acuity Chart. Thirty-six normally sighted young adults completed chart testing under normal and simulated low-vision conditions. Fifty-eight low-vision subjects (thirty with macular pathology and twenty-eight with non-macular pathology) and fifteen normally sighted older subjects completed chart testing with their habitual viewing. We hypothesized that the performance of the normally sighted young adults under simulated low-vision conditions would match the corresponding performance of actual low-vision subjects. RESULTS: When simulating low-vision conditions with visual acuity better than 1.50 logMAR (Snellen 20/630) and contrast sensitivity better than 0.15 log unit, the simulation adequately reduced the acuity and contrast sensitivity in normally sighted young subjects to the desired low-vision levels. When performing the MNREAD test with simulated low vision, the normally sighted young adults had faster maximum reading speed than both the Non-macular and Macular groups, by an average of 0.07 and 0.12 log word per minute, respectively. However, they adequately replicated the reading acuity as well as the critical print size, up to 2.00 logMAR of both low-vision groups. CONCLUSION: A low-vision simulation based on clinical measures of visual acuity and contrast sensitivity can provide good estimates of reading performance and the accessibility of digital text for a broad range of low-vision conditions.

Reconciling print-size and display-size constraints on reading.

Two fundamental constraints limit the number of characters in text that can be displayed at one time-print size and display size. These dual constraints conflict in two important situations-when people with normal vision read text on small digital displays, and when people with low vision read magnified text. Here, we describe a unified framework for evaluating the joint impact of these constraints on reading performance. We measured reading speed as a function of print size for three digital formats (laptop, tablet, and cellphone) for 30 normally sighted and 10 low-vision participants. Our results showed that a minimum number of characters per line is required to achieve a criterion of 80% of maximum reading speed: 13 characters for normally sighted and eight characters for low-vision readers. This critical number of characters is nearly constant across font and display format. Possible reasons for this required number of characters are discussed. Combining these character count constraints with the requirements for adequate print size reveals that an individual's use of a small digital display or the need for magnified print can shrink or entirely eliminate the range of print size necessary for achieving maximum reading speed.

Complete cross-frequency transfer of tone frequency learning after double training.

A person's ability to discriminate fine differences in tone frequency is vital for everyday hearing such as listening to speech and music. This ability can be improved through training (i.e., tone frequency learning). Depending on stimulus configurations and training procedures, tone frequency learning can either transfer to new frequencies, which would suggest learning of a general task structure, or show significant frequency specificity, which would suggest either changes in neural representations of trained frequencies, or reweighting of frequency-specific neural responses. Here we tested the hypothesis that frequency specificity in tone frequency learning can be abolished with a double-training procedure. Specifically, participants practiced tone frequency discrimination at 1 or 6 kHz, presumably encoded by different temporal or place coding mechanisms, respectively. The stimuli were brief tone pips known to produce significant specificity. Tone frequency learning was indeed initially highly frequency specific (Experiment 1). However, with additional exposure to the other untrained frequency via an irrelevant temporal interval discrimination task, or even background play during a visual task, learning transferred completely (1-to-6 kHz or 6-to-1 kHz; Experiments 2-4). These results support general task structure learning, or concept learning in our term, in tone frequency learning despite initial frequency specificity. They also suggest strategies to design efficient auditory training in practical settings. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Preserved tactile acuity in older pianists.

A previous study from our lab demonstrated retention of high tactile acuity throughout the lifespan in blind subjects in contrast to the typical decline found for sighted subjects (Legge, Madison, Vaughn, Cheong & Miller, Percept Psychophys, 70 (8), 1471-1488, 2008). We hypothesize that preserved tactile acuity in old age is due to lifelong experience with focused attention to touch and not to blindness per se. Proficient pianists devote attention to touch - fingerings and dynamics - over years of practice. To test our hypothesis, we measured tactile acuity in groups of ten young (mean age 24.5 years) and 11 old (mean age 64.7 years) normally sighted pianists and compared their results to the blind and sighted subjects in our 2008 study. The pianists, like the subjects in 2008, were tested on two tactile-acuity charts requiring active touch, one composed of embossed Landolt rings and the other composed of dot patterns similar to braille. For both tests, the pianists performed more like the blind subjects than the sighted subjects from our 2008 study. For the ring chart, there was no significant difference in tactile acuity between the young and old pianists and no significant difference between the pianists and the blind subjects. For the dot chart, the pianists showed an age-related decline in tactile acuity, but not as severe as the sighted subjects from 2008. Our results are consistent with the hypothesis that lifelong experience with focused attention to touch acts to preserve tactile acuity into old age for both blind and sighted subjects.

Reading with letter transpositions in central and peripheral vision.

We used a letter transposition (LT) technique to investigate letter position coding during reading in central and peripheral vision. Eighteen subjects read aloud sentences in a rapid serial visual presentation task. The tests contained a baseline and three LT conditions with initial, internal, and final transpositions (e.g., "reading" to "erading", "raeding", and "readign"). The four reading conditions were tested in separate blocks. We found that LT had a smaller cost on peripheral (10° lower field) than on central reading speed, possibly due to the higher intrinsic position uncertainty of letters in the periphery. The pattern of cost (initial > final > internal) was the same for central and peripheral vision, indicating a similar lexical route for both. In the periphery, LT only affected transposed words, while in central vision it also affected untransposed words. This spread of the LT effect in central vision could not be accounted for by increased attention or memory load, or by decreased sentence context.

Reading Acuity as a Predictor of Low-Vision Reading Performance.

Purpose: Most people with low vision experience difficulty with reading. Reading assessment can provide guidance for prescription of reading aids and strategies for reading rehabilitation. Here we investigate the effectiveness of letter acuity (LA) and reading acuity (RA) as predictors of low-vision reading performance. Methods: Low-vision subjects (n = 58), young control subjects (n = 52), and older control subjects (n = 14) participated in this study. The low-vision subjects were separated into a Macular group (n = 30) and a Nonmacular group (n = 28) based on whether the diagnoses primarily affected the macular area. LA was measured with the Lighthouse Distance Visual Acuity Chart and RA with the MNREAD Acuity Chart. Reading speeds were obtained across a range of print sizes from the MNREAD test. The MNREAD data were used to estimate required print sizes for three functionally important types of reading for each subject: spot reading (40 words/min [wpm]), fluent reading (80 wpm), and critical print size (required to achieve maximum reading speed). Results: For equal values of LA, the Macular group had significantly worse RA than the Nonmacular group. The differences between vision groups, as well as individual variations within groups, were largely explained by the differences in RA. RA is a better predictor than LA for spot reading size, fluent reading size, and critical print size. Conclusions: RA may provide more accurate assessment of reading performance than LA for purposes of low-vision reading rehabilitation.

Fonts Designed for Macular Degeneration: Impact on Reading.

Purpose: People with macular degeneration (MD) experience difficulties in reading due to central-field loss. Two new fonts, Eido and Maxular Rx, have been designed specifically for individuals with MD. We have compared reading performance of these new fonts with three mainstream fonts (Times-Roman, Courier, and Helvetica). Methods: Subjects with MD (n = 19) and normally sighted subjects (n = 40) were tested with digital versions of the MNREAD test using the five fonts. Maximum reading speed (MRS), critical print size (CPS), and reading acuity (RA) were estimated to characterize reading performance. Physical properties of the fonts were quantified by interletter spacing and perimetric complexity. Results: Reading with MD showed font differences in MRS, CPS, and RA. Compared with Helvetica and Times, Maxular Rx permitted both smaller CPS and RA, and Eido permitted smaller RA. However, the two new fonts presented no advantage over Courier. Spacing, but not Complexity, was a significant predictor of reading performance for subjects with MD. Conclusions: The two fonts, designed specifically for MD, permit smaller print to be read, but provide no advantage over Courier.

Bottom-up and top-down influences at untrained conditions determine perceptual learning specificity and transfer.

Perceptual learning is often orientation and location specific, which may indicate neuronal plasticity in early visual areas. However, learning specificity diminishes with additional exposure of the transfer orientation or location via irrelevant tasks, suggesting that the specificity is related to untrained conditions, likely because neurons representing untrained conditions are neither bottom-up stimulated nor top-down attended during training. To demonstrate these top-down and bottom-up contributions, we applied a "continuous flash suppression" technique to suppress the exposure stimulus into sub-consciousness, and with additional manipulations to achieve pure bottom-up stimulation or top-down attention with the transfer condition. We found that either bottom-up or top-down influences enabled significant transfer of orientation and Vernier discrimination learning. These results suggest that learning specificity may result from under-activations of untrained visual neurons due to insufficient bottom-up stimulation and/or top-down attention during training. High-level perceptual learning thus may not functionally connect to these neurons for learning transfer.

Location and direction specificity in motion direction learning associated with a single-level method of constant stimuli.

Recent studies reported significantly less location specificity in motion direction learning than in previous classical studies. The latter performed training with the method of constant stimuli containing a single level of direction difference. In contrast the former used staircase methods that varied the direction difference trial by trial. We suspect that extensive practice with a single direction difference could allow an observer to use some subtle local cues for direction discrimination. Such local cues may be unavailable at a new stimulus location, leading to higher location specificity. To test this hypothesis, we jittered slightly the directions of a stimulus pair by the same amount while keeping the direction difference constant, so as to disturb the potential local cues. We observed significantly more transfer of learning to untrained locations. The local cue effects may also explain the recent controversies regarding the finding that foveal motion direction learning becomes significantly more transferrable to a new direction with TPE (training-plus-exposure) training. One specific study by Zili Liu and collaborators that challenges this finding also used a single-level direction difference for training. We first replicated their results. But we found that if the directions of the stimulus pair were again jittered while the direction difference was kept constant, motion direction learning transferred significantly more to an orthogonal direction with TPE training. Our results thus demonstrate the importance of using appropriate psychophysical methods in training to reduce local-cue related specificity in perceptual learning.

Perceptual learning eases crowding by reducing recognition errors but not position errors.

When an observer reports a letter flanked by additional letters in the visual periphery, the response errors (the crowding effect) may result from failure to recognize the target letter (recognition errors), from mislocating a correctly recognized target letter at a flanker location (target misplacement errors), or from reporting a flanker as the target letter (flanker substitution errors). Crowding can be reduced through perceptual learning. However, it is not known how perceptual learning operates to reduce crowding. In this study we trained observers with a partial-report task (Experiment 1), in which they reported the central target letter of a three-letter string presented in the visual periphery, or a whole-report task (Experiment 2), in which they reported all three letters in order. We then assessed the impact of training on recognition of both unflanked and flanked targets, with particular attention to how perceptual learning affected the types of errors. Our results show that training improved target recognition but not single-letter recognition, indicating that training indeed affected crowding. However, training did not reduce target misplacement errors or flanker substitution errors. This dissociation between target recognition and flanker substitution errors supports the view that flanker substitution may be more likely a by-product (due to response bias), rather than a cause, of crowding. Moreover, the dissociation is not consistent with hypothesized mechanisms of crowding that would predict reduced positional errors.