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PubMed1981

Adaptation to visual displacement: contribution of proprioceptive, visual, and attentional factors.

A study is reported of the sensory and oculomotor factors that influence adaptation to visual displacement when only sight of the hand and of a target light is permitted. Ten subjects each participated in five counterbalanced sessions in which the relative contributions to adaptation of limb proprioception, oculomotor pursuit, retinal image displacement, and attention were determined. Recordings of eye position were taken throughout the sessions. A discordance between the visual direction of the hand and the proprioceptively specified position of the hand was essential but not sufficient for adaptation to occur. When such a discordance was present adaptation was enhanced by improving position sense of the arm by moving it passively, maximizing accuracy of visual tracking, and focusing attention on the hand. Attentional factors played a smaller part than has been reported for exposure situations involving error feedback about limb position. Eye-movement recordings showed that tracking the passively moved hand visually was vastly superior to tracking a target light undergoing comparable motion.

Adaptation, Ocular↗

PubMed1985

Dynamic visual capture: apparent auditory motion induced by a moving visual target.

Apparent motion of a sound source can be induced by a moving visual target. The direction of the perceived motion of the sound source is the same as that of the visual target, but the subjective velocity of the sound source is 25-50% of that of the visual target measured under the same conditions. Eye tracking of the light target tends to enhance the apparent motion of the sound, but is not a prerequisite for its occurrence. The findings are discussed in connection with the 'visual capture' or 'ventriloquism' effect.

Adult↗

PubMed1998

Preferred position of visual displays relative to the eyes: a field study of visual strain and individual differences.

At office workplaces equipped with visual display units (VDU) that were adjustable to various positions relative to the eyes short and long viewing distances from the eyes to the screen were imposed (mean value of about 63 and 92 cm) at two levels of screen height so that the visual target was either at eye level or 18 cm below, on the average. The change from far to near viewing distance produced a larger increase in eyestrain when the VDUs were at eye level. High screens resulted in greater eyestrain than low screens, as shown by correlations over subjects. When operators were free to adjust the most comfortable screen position, the group of 22 participants preferred viewing distances between 60 and 100 cm and vertical inclination of gaze direction between horizontal and -16 degrees downwards. However, within most subjects the range of preferred screen positions was much smaller. Between 3 days during a 1-month period the test-retest correlations of the preferred screen positions were highly significant, both for viewing distance and vertical gaze inclination. When operators were forced to work at a shorter distance than their preferred viewing distance they reported more visual strain. Thus, operators appear to prefer an individual adjustment of the screen relative to the eyes in order to avoid visual strain and discomfort at VDU work.

Adult↗

PubMed1996

Transitions in Visual Proprioception: A Cross-Sectional Developmental Study of the Effect of Visual Flow on Postural Control.

In the present study, a moving room paradigm was used that characterized the developmental progression of the effects of visual perturbations on stance control in subjects (N = 39) from 5 months to 10 years of age. Kinematic (probability of recording sway, magnitude of sway response) and electromyographic (probability and patterns of muscle activation, muscle onset latencies) data were found that suggested that visual flow simulating sway activates organized postural muscle responses and results in subsequent sway in standing infants as young as 5 months of age, well before they are able to stand independently. In new walkers, there was an increase in the magnitude of the effect of the visual perturbation, suggesting a possible increase in reliance on visual information. The magnitude of sway decreased to very low levels in older children and adults. The large-amplitude responses observed in the youngest age groups may indicate an inability to switch from an unreliable to a reliable source of perceptual information or an inability to modulate the responses produced following the perturbations. With increasing age and experience, the ability to resolve the conflict increased, with adult subjects demonstrating little sway response.

Journal Article↗

PubMed1997

Visual BLAST and visual FASTA: graphic workbenches for interactive analysis of full BLAST and FASTA outputs under MICROSOFT WINDOWS 95/NT.

MOTIVATION: When routinely analysing protein sequences, detailed analysis of database search results made with BLAST and FASTA becomes exceedingly time consuming and tedious work, as the resultant file may contain a list of hundreds of potential homologies. The interpretation of these results is usually carried out with a text editor which is not a convenient tool for this analysis. In addition, the format of data within BLAST and FASTA output files makes them difficult to read. RESULTS: To facilitate and accelerate this analysis, we present for the first time, two easy-to-use programs designed for interactive analysis of full BLAST and FASTA output files containing protein sequence alignments. The programs, Visual BLAST and Visual FASTA, run under Microsoft Windows 95 or NT systems. They are based on the same intuitive graphical user interface (GUI) with extensive viewing, searching, editing, printing and multithreading capabilities. These programs improve the browsing of BLAST/FASTA results by offering a more convenient presentation of these results. They also implement on a computer several analytical tools which automate a manual methodology used for detailed analysis of BLAST and FASTA outputs. These tools include a pairwise sequence alignment viewer, a Hydrophobic Cluster Analysis plot alignment viewer and a tool displaying a graphical map of all database sequences aligned with the query sequence. In addition. Visual Blast includes tools for multiple sequence alignment analysis (with an amino acid patterns search engine), and Visual FASTA provides a GUI to the FASTA program.

Amino Acid Sequence↗

PubMed1986

Components of visual attention. Alterations in response pattern to visual stimuli following parietal lobe infarction.

The contribution of attentional factors per se in response to visual stimuli was studied in patients with unilateral lesions of the left or right cerebral hemispheres. Subjects were required to respond to visual targets that were presented tachistoscopically, and were preceded by spatial cues that served to manipulate the spatial locus of attention. On 'valid' cue trials, the cue directed attention to the target's spatial coordinates; on 'invalid' cue trials, the cue misdirected attention. It was determined that damage to either the left or right hemisphere results in a general slowing of reaction times to visual stimuli irrespective of where such stimuli appear, and that patients with right parietal lesions are further impaired at shifting attention within the left visual field.

Adult↗

PubMed2006

Visual constructive and visual-motor skills in deaf native signers.

Visual constructive and visual-motor skills in the deaf population were investigated by comparing performance of deaf native signers (n=20) to that of hearing nonsigners (n=20) on the Beery-Buktenica Developmental Test of Visual-Motor Integration, Rey-Osterrieth Complex Figure Test, Wechsler Memory Scale Visual Reproduction subtest, and Stanford-Binet Intelligence Scale Paper Folding and Cutting subtest. Deaf signers were found to perform similarly to hearing controls, suggesting that these tests are valid assessment instruments to use with deaf individuals.

Adult↗

PubMed2002

The visual word form area: a prelexical representation of visual words in the fusiform gyrus.

Event-related fMRI was used to test the hypothesis that the visual word form area in the left fusiform gyrus holds a modality-specific and prelexical representation of visual words. Subjects were engaged in a repetition-detection task on pairs of words or pronounceable pseudo-words that could be written or spoken. The visual word form area responded only to written stimuli, not to spoken stimuli, independently of their semantic content. We propose that the occasional activation of the fusiform gyrus when listening to spoken words is due to the topdown recruitment of visual orthographic or object representations.

Adult↗

PubMed1998

Device visualization for interventional MRI using local magnetic fields: basic theory and its application to catheter visualization.

This paper addresses one of the major problems in Interventional magnetic resonance imaging (MRI): the visualization of interventional devices. For visualization locally induced magnetic fields are used, which disturb the homogeneity of the main magnetic field of the MR scanner. This results in signal loss in the vicinity of the device due to intravoxel dephasing, and leads to a disturbance of the phase image. The local fields are established by a low current in a closed copper loop along the device. This method will be introduced as a means for catheter visualization. The basic theory behind this method is presented. Simulations are performed to determine the effect of intravoxel dephasing, without interfering effects like susceptibility or radio-frequency artifacts. Scanned and simulated data is used to verify the theoretical consideration. Different configurations of wire loops are discussed and two types of catheter visualization scans are proposed. Results from a pig study show that this methods holds promise for intravascular interventions under MRI guidance.

Animals↗

PubMed1998

Two visual pigments in a single photoreceptor cell: identification and histological localization of three mRNAs encoding visual pigment opsins in the retina of the butterfly Papilio xuthus.

This paper describes the localization of newly identified visual pigment opsins in the tiered retina of the Japanese yellow swallowtail Papilio xuthus. We first cloned three cDNAs encoding visual pigment opsins, PxRh1, PxRh2 and PxRh3, and then carried out histological in situ hybridization to localize their mRNAs in the retina. By combining the present data with our previous electrophysiological results, we concluded that both PxRh1 and PxRh2 correspond to visual pigments expressed in photoreceptor cells sensitive in the green wavelength region (green receptors), whereas PxRh3 corresponds to a pigment in red receptors. The in situ hybridization studies showed that some photoreceptor cells express two opsin mRNAs. In the ventral half of the eye, all green receptors in the distal tier were labelled by both PxRh1 and PxRh2 probes. The labelling by the PxRh2 and PxRh3 probes was detected throughout the eye in the proximal tier; in 18 % of ommatidia, the probes labelled the same photoreceptor cell. These results suggest that the possible co-localization of two different visual pigments will broaden the sensitivity spectrum of the photoreceptor cells.

Amino Acid Sequence↗

PubMed2003

Visual aids and structured criteria for improving visual inspection and interpretation of single-case designs.

Because behavior analysis is a data-driven process, a critical skill for behavior analysts is accurate visual inspection and interpretation of single-case data. Study 1 was a basic study in which we increased the accuracy of visual inspection methods for A-B designs through two refinements of the split-middle (SM) method called the dual-criteria (DC) and conservative dual-criteria (CDC) methods. The accuracy of these visual inspection methods was compared with one another and with two statistical methods (Allison & Gorman, 1993; Gottman, 1981) using a computer-simulated Monte Carlo study. Results indicated that the DC and CDC methods controlled Type I error rates much better than the SM method and had considerably higher power (to detect real treatment effects) than the two statistical methods. In Study 2, brief verbal and written instructions with modeling were used to train 5 staff members to use the DC method, and in Study 3, these training methods were incorporated into a slide presentation and were used to rapidly (i.e., 15 min) train a large group of individuals (N = 87). Interpretation accuracy increased from a baseline mean of 55% to a treatment mean of 94% in Study 2 and from a baseline mean of 71% to a treatment mean of 95% in Study 3. Thus, Study 1 answered basic questions about the accuracy of several methods of interpreting A-B designs; Study 2 showed how that information could be used to increase the accuracy of human visual inspectors; and Study 3 showed how the training procedures from Study 2 could be modified into a format that would facilitate rapid training of large groups of individuals to interpret single-case designs.

Audiovisual Aids↗

PubMed2005

Subjective visual vertical and subjective visual horizontal measures in patients with chronic dizziness.

OBJECTIVES: We aimed to find the frequency of otolith organ pathologies in the clinical picture of common dizziness etiologies in the chronic stage. METHOD: Subjective visual vertical and subjective visual horizontal measures were assessed in patients who had persistent or recurrent dizziness at least 2 months after the acute period. Every patient was tested in three head positions: neutral, right, or left deviation in the roll plane. Test results were compared with those of the control group. RESULTS: Seventy-three patients and 18 controls were examined. Fifty-eight of the patients had peripheral vestibular disease; 15 of them had central vestibular disease. Left subjective visual horizontal (SVH) and right SVH measures of the peripheral group were significantly different from those of the control group (p < .01). There was no difference in any test between the peripheral and central groups. When we put a cut off point for abnormality (0, 1) according to mean +/- 2 SD of the control group, the peripheral and central groups had very high significant differences from the control group. Approximately 25 to 50% of our patients had pathologic subjective visual vertical or SVH measures according to test type. CONCLUSION: These results showed that the otolith system must be evaluated in the chronic period of dizziness, especially in patients who frequently visit their physician, and modifications in treatment programs must be conducted.

Adult↗

PubMed2004

[Visual impression of photographic density of lung, thorax, and mediastinum in chest CT images: verification of optical illusion by visual subjective evaluation of medical images].

Even if the brain in head CT images is shown physically at the same photographic density, optical illusion (assimilation, contrast, etc.) occurs and practical density can be observed psychologically differently. Therefore, in this study, in order to clarify the visual characteristics of lightness perception in chest CT images, I attempted to compare it with the visual impression of the photographic density of lung, thorax, and mediastinum, using visual subjective evaluation. The results were as follows. (1) In the case of the preferential window setting of lung, both thorax and mediastinum, which surround the lung, are recognized as a wide white frame with contrast, and the photographic density of the lung psychologically seems blackish as a result of the "picture frame effect". (2) In the case of the preferential window setting of thorax and mediastinum, the visual impression of the photographic density varies among observers. (3) In the case of the virtual double window setting of lung, thorax, and mediastinum, under the influence of both high-density and low-density areas in the radiological anatomy of thorax and mediastinum, the photographic density of lung psychologically appears whitish as a result of the "grouping theories" of lightness computation. Further, under the influence of original gray lung, the photographic densities of thorax and mediastinum psychologically appear to be whitish.

Humans↗

PubMed1989

Effects of visual acuity and visual motor speed and dexterity on cognitive test performance.

This study examined the hypothesis that near visual acuity and visual motor speed and dexterity contribute significantly to performance on cognitive tests that place a premium on these functions. Near visual acuity for both eyes, Finger Tapping Test - average taps with dominant hand, and Grooved Pegboard Test - dominant hand time, served as the independent variables. The dependent variables were Trail Making Test-Part B and the Performance subtests of the Wechsler Adult Intelligence Scale. Results indicated that while visual acuity was significantly correlated with all six test variables, it did not contribute to the regression model as well as Pegboard time or Tapping speed. Pegboard time and Tapping speed contributed to the regression model, but in different ways depending upon which test was examined.

Journal Article↗

PubMedDate not supplied

[Urine analysis in a pediatric laboratory using reagent strips read visually (visual dip sticks)].

The Authors studied the possibility of using some dip sticks visual for urinalysis. One hundred of urine samples have been analyzed at the beginning with the instrumental laboratory analytical system and then with the dip sticks visual; the results put in evidence that there is a real discrepancy as far as glucose is concerned. Glucose is overestimated in dip sticks visual method. Bilirubin, blood and proteins are in a decreasing order the most different items. Concerning to pH the results have been comparable. Specific weight cannot be compared to the laboratory method, on the other hand it can be used for screening. On the whole the Authors are quite satisfied about dip sticks visual method; it can be used in order to accelerate diagnosis and avoid pre-analytical mistakes.

Age Factors↗

PubMed1980

Visually evoked response asymmetries in a family with congenital nystagmus: possible evidence of abnormal visual projections.

Flash-evoked visual responses of two patients from a family with congenital nystagmus showed marked asymmetry between the recordings from the right and left occipital regions in response to monocular stimulation. The asymmetries were crossed, ie, the degree of abnormality inverted when the stimulus changed from one eye to the other. Stimulation of both eyes together evoked symmetrical responses from the two hemispheres. The patients had no signs of abnormality involving the visual pathways. The changes in the visually evoked responses were similar to those found in human albinos, who are known to have abnormal retinostriate projections and also nystagmus.

Adult↗

PubMed1998

Identifying the content area for the 51-item National Eye Institute Visual Function Questionnaire: results from focus groups with visually impaired persons.

OBJECTIVE: To identify the content area for a questionnaire designed to measure vision-targeted health-related quality of life and to determine whether problems with vision-related functioning are qualitatively similar across different common eye diseases. DESIGN: Twenty-six condition-specific focus groups were conducted with 246 patients from 5 geographic regions to identify the content area for a questionnaire for use among persons with diabetic retinopathy, glaucoma, macular degeneration, cytomegalovirus retinitis, and cataract. A standard protocol was used to structure each focus group discussion. Sessions were audiotaped, transcribed, and coded in preparation for a content analysis. SETTINGS: Five university-based ophthalmology practices and 1 nonprofit eye care foundation. PARTICIPANTS: Eligible participants had to have 1 of the following eye conditions: age-related cataracts, age-related macular degeneration, diabetic retinopathy, primary open angle glaucoma, cytomegalovirus retinitis, or low vision from any cause. All eligible persons were older than 21 years, spoke English, and had sufficient cognitive function to provide informed consent. RESULTS: Among the 246 participants, 2623 problems with vision-related functioning were mentioned. The mean number of problems per person ranged from 13.5 for those with diabetic retinopathy to 7.9 for persons with glaucoma. For the sample overall, reading problems were mentioned most frequently, followed by driving, general problems with seeing clearly, and mental health complaints caused by vision. Although the proportion of persons who reported each problem varied by condition, at least some persons with each eye disease reported each problem. The 3 most common descriptors associated with each problem were difficulty or ease of performance (13%), psychological distress associated with performance of the activity (11%), and complete inability to participate in a visual activity (11%). CONCLUSION: An item-generation strategy for a new questionnaire using a standardized focus group method identified content areas and aspects of visual disability that are not included in currently available vision-specific instruments that assess the impact of common eye diseases on visual functioning in every-day life. Although participants mentioned problems that were unique to their disease, across conditions the problems mentioned were similar. These findings provide empirical evidence of content validity for a vision-targeted, health-related quality-of-life survey designed for use across conditions.

Adult↗

PubMed1992

Visual evoked potential estimation of visual activity with a Laplacian derivation.

Visual acuity was estimated with visual evoked potentials in 13 healthy subjects. A Laplacian derivation of 5 electrodes was used to improve the signal-to-noise ratio and to enhance striate cortical activity selectively. In 6 subjects, the Laplacian derivation gave a more reliable estimation of visual acuity than did a single midline derivation. In the other 7 subjects, the quality of both estimations was comparable.

Electrodes↗