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PubMed2004

Ubiquitous computing technology for just-in-time motivation of behavior change.

This paper describes a vision of health care where "just-in-time" user interfaces are used to transform people from passive to active consumers of health care. Systems that use computational pattern recognition to detect points of decision, behavior, or consequences automatically can present motivational messages to encourage healthy behavior at just the right time. Further, new ubiquitous computing and mobile computing devices permit information to be conveyed to users at just the right place. In combination, computer systems that present messages at the right time and place can be developed to motivate physical activity and healthy eating. Computational sensing technologies can also be used to measure the impact of the motivational technology on behavior.

Health Behavior↗
PubMed2000

Optomotor course control in flies with largely asymmetric visual input.

We have studied freely flying and walking flies as well as flies flying in a flight simulator in order to discover how functionally blinding one of the eyes affects the fly's ability to move straight. It is hard to tell just by observing the animals' movements whether they have been deprived of vision in one eye. Statistical analysis is need to show that there are differences in the locomotory paths of monocular and binocular flies: monocular flies tend to turn slightly towards the side of the seeing eye. It is possible that the superimposed translational and rotational optic flow fields, generated on the trajectory of monocular flies, sum to zero net flow. This overall flow over the retina of the open eye might lead to a state of optomotor equilibrium.

Animals↗
PubMed2005

Automatic image orientation detection via confidence-based integration of low-level and semantic cues.

Automatic image orientation detection for natural images is a useful, yet challenging research topic. Humans use scene context and semantic object recognition to identify the correct image orientation. However, it is difficult for a computer to perform the task in the same way because current object recognition algorithms are extremely limited in their scope and robustness. As a result, existing orientation detection methods were built upon low-level vision features such as spatial distributions of color and texture. Discrepant detection rates have been reported for these methods in the literature. We have developed a probabilistic approach to image orientation detection via confidence-based integration of low-level and semantic cues within a Bayesian framework. Our current accuracy is 90 percent for unconstrained consumer photos, impressive given the findings of a psychophysical study conducted recently. The proposed framework is an attempt to bridge the gap between computer and human vision systems and is applicable to other problems involving semantic scene content understanding.

Algorithms↗
PubMed1985

A high-speed point plotter for vision research.

An electronic interface is described that allows high speed plotting of points on an oscilloscope under the control of a computer. The storage and fast data manipulation done by the interface permit inexpensive computers of modest performance to produce complex displays which could otherwise be produced only by costly high speed computer graphics systems.

Data Display↗
PubMedDate not supplied

[Mutism in children].

INTRODUCTION: Mutism is absence of verbal expression with conservation of language comprehension. The origin of mutism is multifactorial and may followed from cranial trauma surgery of the posterior fossa, acquired epileptic syndromes and psychogenic origin. OBJECTIVE: To refer patients who had presented mutism of diverse etiology. CLINICAL CASES: We analysed three children who had presented mutism originated by diverse causes. Case 1. A child with family and school problems, attention deficits and limited communication resources. Neurological examination and other auxiliary test (EEG) were normal. He presented no alteration in language or speech. We recommended the change of the school and a psychotherapeutic orientation. Case 2. A 4 year old female child who has suffered varicella 15 days earlier and presented limitations in her verbal expression despite maintain her linguistically capacity. She showed a indifferent behavior and her movements were without finality. Neurological examination was normal. The girl understood and followed instruction properly. However her verbal communication was absent. Total recuperation occurred in 72 hours. Case 3. A 12 years old child who had suffered a cranial traumatism with loss of consciousness ten days earlier. After this traumatism, he presented behavior changes, disorientation and blurred vision. Additionally he presented stereotypies and limitations in psychosocial connections. Despite his mutism, he conserved the structure and content of language. SPECT showed hypoperfusion in orbitotemporal region. Improvement was total 20 days after his traumatism. CONCLUSIONS: The mutism has multifactorial etiology. References were made to three cases who's mutism was related to emotional causes, post-varicella complications and posttraumatic events.

Attention Deficit Disorder with Hyperactivity↗
PubMed1995

Retinotopic and directional defects in motion discrimination in humans with cerebral lesions.

We investigated the discrimination of motion direction in peripheral and central vision in 23 patients with unilateral cerebral hemispheric lesions on computed tomography or magnetic resonance imaging. We used random dot cinematograms that determined a percent coherence motion threshold for 16 points in the peripheral field and for four directions separately in central vision. We measured asymmetry of right- versus left-field peripheral discrimination (retinotopic defects) and asymmetry of central discrimination for rightward versus leftward motion (directional defects), compared with normal subjects. Five patients had directional asymmetries of foveal motion perception, all worse for motion toward the side of their lesions. One patient had a bidirectional defect for the perception of horizontal motion. For 3 of these 6, the average of all horizontal and vertical motion discrimination thresholds was also elevated. Two had contralateral retinotopic defects. One of these also had an ipsidirectional foveal defect, but the other did not. The remaining 5 patients with ipsidirectional foveal defects had hemianopias that precluded testing for coexistent retinotopic defects. The lesions of the 6 patients with ipsidirectional defects overlapped in white matter underlying the lateral temporo-occipital cortex, at the junction of Brodmann areas 19 and 37. In contrast, lesions of patients without directional defects spared this region.

Adult↗
PubMed1995

Overview of technology for low vision.

This article provides an overview of technology resources and services to assist persons with low vision in maintaining independent function in the home, community, and educational and vocational settings. Case studies are provided to demonstrate the integration of technology into the lives of persons with low vision.

Computers↗
PubMed1998

Local interaction fields and adaptive regularizers for surface reconstruction and image relaxation.

A set of novel local interaction fields associated with input point data and adaptive regularizers are introduced for some problems in image processing and early-middle vision. The local interaction field is used to take the place of the delta-error term in conventional approaches. It consists of two parts; one is the usual error term, the other is a window function whose shape, size and orientation can be adapted to local structures in specific applications. Unlike the usual delta-error term, local interaction fields favour local flatness and thus impose smoothing implicitly. Several adaptive regularizers are introduced to keep discontinuities while smoothing. In finding solutions, even the simplest gradient descent algorithm is efficient in many examples. The results are stable under varying parameters and quite robust against noise.

Image Processing, Computer-Assisted↗
PubMed1998

[Standardized evaluation of red, green and blue perception. Comparison between color arrangement and computer-assisted test procedures].

BACKGROUND: Computerized colortests offer the possibility of determining quantitative color contrast thresholds under standardized conditions. Arrangement tests allow semi-quantitative evaluation of the red, green and blue color sense. To validate the results of a new computerized test, its results are compared to those of arrangement tests. PATIENTS AND METHODS: Thirty-five patients with retinitis pigmentosa (RP, mean age 38.51, +/- 15.14) as well as 30 normal observers (mean age 36.52, +/- 14.33) were evaluated. The computerized color test COLDEF was used, which is a calibrated screen that presents color optotypes on a colored background. All colors are chosen from three-color confusion axes of the CIE-Lu'v' color chart (protan, deutan and tritan axis). By a staircase procedure, the colors of the optotype and background were varied until the observers minimal color contrast threshold is detected. To compare the results of COLDEF with a routine diagnostic tool, the Farnsworth panel D-15 and Lanthony désaturé test were chosen. The results of the arrangement tests were scored by a categorization scheme. RESULTS: Normal observers showed no elevated thresholds either in COLDEF nor in the panel tests. In the RP group increased thresholds along the blue confusion axis could be detected in most cases. Furthermore, COLDEF showed increased thresholds along the red and green axes in some patients. With the computerized test it is always possible to identify the color axis concerned. The new test allows a fast and quantitative assessment of acquired color vision deficiencies.

Adult↗
PubMed1991

[The effect of training with computer equipment on the visual analyzer of 1st-grade pupils].

Examination are carried out on 64 school children Ist class from school "104", town of Sofia where computer training on mathematics and mother tongue is introduced in the frames of pedagogic experiment. The studies are performed parallelly at traditional and computer lessons, realized in two variants (with one and two school hours daily). In order to establish the functional status of the visual analyzer during computer training the following methods are used: studying the distance of the nearest point for clear vision (punctum proximum), stability of clear vision, threshold of the electric eye sensitivity, critical frequency of fusing of the light flickerings. A full preliminary ophthalmological examination is made by "Vision test", as well as chronometric control of each student to establish the real time of work with computers. Taken into consideration are also the data for illumination of the working places in the computer studies and class rooms where the traditional school hours are held. The analysis of the data received shows that the computer training (1 and 2 computer lessons daily) with schoolchildren, Ist class, has no unfavourable effect on the functional status of the visual analyzer in the limits of study hours up to 25 minutes.

Accommodation, Ocular↗
PubMed2004

Differential latencies and the dynamics of the position computation process for moving targets, assessed with the flash-lag effect.

To investigate the dynamics of the position computation process for a moving object in human vision, we measured the response to a continuous change in position at a constant velocity (ramp-response) using the flash-lag illusion. In this illusion, flashed and moving objects appear spatially offset when their retinal images are physically aligned. The steady-state phase of the ramp-response was probed using the "continuous-motion" (CM) paradigm, in which the motion of the moving object starts long before the occurrence of the flash. To probe the transient phase of the ramp-response, we used the "flash-initiated cycle" (FIC) paradigm, in which the motion of the moving object starts within a short time window around the presentation of the flash. The sampling instant of the ramp-response was varied systematically by changing the luminance or the presentation time of the flashed stimulus. We found that the perceived flash misalignments in the FIC and CM paradigms were approximately equal when sampling of the ramp-response occurred after a relatively long delay from the onset of motion and, were significantly different when sampling of the ramp-response occurred at a relatively short delay. The systematic variations in the perceived misalignment between the moving and flashed stimuli as a function of stimulus parameters are compared to the predictions of our differential latency and to alternative models of position computation.

Humans↗
PubMedDate not supplied

Computer versus lecture: strategies for teaching fetal monitoring.

The purpose of this study was to determine how well novice nurses learned basic fetal monitoring concepts from a computer-assisted instructional program and a scripted lecture with equivalent content. A pretest-posttest experimental design was conducted. Forty-eight junior baccalaureate nursing students beginning their first maternity rotation were recruited for the study from a southwestern university. Thirty-nine students provided complete data sets. None had prior experience or education in fetal monitoring. Two strategies were used to teach basic fetal monitoring concepts: a scripted lecture with black-and-white transparencies and an equivalent computer-assisted instructional program. Statistical significance was set at p = 0.05. There were no significant differences between the computer and lecture groups' learning on the basis of age, education, or vision. There was a positive, nonsignificant gain in mean scores from the pretest to the posttest for both groups. The greatest difference was in the program completion time with the computer-assisted instruction group completing the program 43.6% faster than the lecture group.

Audiovisual Aids↗
PubMed1978

A method for plotting the optimum positions of an array of cortical electrical phosphenes.

The cortical visual prosthesis provides one approach to the substitution of vision in blind people. Usable visual information is provided in the form of phosphenes, and in order to make use of the prosthesis the positions of the phosphenes in visual space must first be determined. Such phosphene maps have to be constructed from observations of the angle and distance between various pairs of phosphenes. Because of the variation in repeated observations of the same phosphene pair, some method is needed to provide the 'best' fitting map to the observations. By formulating the problem as one involving the minimization of a function of many variables, an algorithm is constructed which determines a two-dimensional co-ordinate for each phosphene by minimizing one of two criteria indicating the fit of the map to the observations. The minimization algorithm employed is, essentially, a 'steepest descent' procedure, and initial co-ordinate values are provided by a triangulation method.

Blindness↗
PubMed2001

Stability of visual field enlargements following computer-based restitution training -- results of a follow-up.

In a previous randomized placebo-controlled clinical trial, we observed significant visual field enlargements induced by computer-based restitution training in patients with cerebral lesions (Kasten et al., Nature med., 4, 1998, 1083-87). Now we asked the question whether this effect is stable after training was discontinued? Here we report data of a follow-up study after a training-free interval (mean 23.5 +/- 2.3 months after end of therapy). 16 patients of the original restitution group and 6 patients of the placebo group were re-examined. On average, in high resolution computer campimetry (stimulus detection: PeriMa, form recognition: PeriForm, color perception: PeriColor) as well as in conventional automatic perimetry (TAP-2000) both groups showed no significant decline in the number of correctly detected stimuli after training was discontinued. However, cluster analysis revealed three different types of patients, who showed either increase (Type-I), decrease (Type-II) or stability (Type-III) in performance. We propose that many patients learn to use the regained visual capacities not only in the setting of a computer training but also in every day life, while other patients do not use the areas of restored vision and show a decrease of visual functions after the end of training. The Type-I group does not need continuous training, while the Type-II group may benefit from phases of refreshment exercises.

Adult↗
PubMed2006

An assessment of the video image quality required in a remote vision guidance system for visually impaired pedestrians.

A study was carried out to determine the most acceptable quality of video images for use in remote guidance of visually impaired pedestrians. A video image clip of 20 s duration was captured using a digital camera, while walking a sample route. The video image clip was encoded at bit rates of 30 and 48 kbit/s, and frame rates of 10, 7.5, 5 and 2.7 fps. Two standard resolutions were used: Quarter Common Intermediate Format (QCIF) (176 x 144 pixels) and Common Intermediate Format (CIF) (352 x 288 pixels). Twelve participants gave their judgment on the picture update rate (smoothness of movement), the bit rate and the static resolution. The mean scores for total quality (five-point scale) ranged from 3.3 to 4.8, but there was no significant difference between them. The mean scores for smoothness (five-point scale) ranged from 3.0 to 4.7, but there was no significant difference between them. The mean score for the resolution of the QCIF video clips was 2.9 (SD = 0.9) and for the CIF recordings were 4.1 (SD = 0.7), but there was no significant difference between them. The majority of the participants were most comfortable with video which was transmitted at 48 kbit/s and 7.5 fps. Therefore, this quality can be considered satisfactory for remote guidance.

Adult↗
PubMed1997

Chromatic-contrast threshold impairment in diabetes.

A prospective study was carried out to investigate acquired colour-vision deficits in diabetics using an automated, computer-controlled, cathode-ray-tube based test of chromatic contrast. Chromatic-contrast thresholds estimates were measured along both a red/ green (constant S-cone) confusion axis and a tritan (constant M/L-cone) confusion axis for 305 eyes of 305 diabetics. The diabetic data were partitioned into groups based on a clinical categorisation of retinopathy. The diabetic data were compared with both age-matched and 'lens-equated' control data obtained from a bank of 347 normal subjects. Further analysis of differences between diabetic-status groups was performed. Associations between chromatic contrast threshold estimates and age, duration of disease, and severity of both macular oedema and ischaemia were investigated. The diabetic group was found to have significantly reduced chromatic-contrast threshold estimates when compared with normal controls, even in the absence of retinopathy. This reduction in chromatic contrast was predominantly tritanopic in nature. Interestingly, no reduction in red/green chromatic-contrast threshold estimate was found in diabetics without retinopathy. The tritan deficit seen in diabetics without retinopathy was strongly correlated with duration of disease, but when adjustments were made to account for the effects of duration-dependent lens yellowing, the tritan deficit was no longer apparent. A correlation between both the severity of macular oedema and severity of ischaemia with chromatic-contrast loss was established. Acquired reductions in both red/green and tritan chromatic-contrast threshold estimates seen in diabetics are strongly correlated with the severity of retinopathy. The results provide evidence that the specific tritan deficits seen in diabetics can be explained by the effects of lens yellowing rather than by selective damage of the blue cone system as has been hypothesised by other groups. The results provide support for the potential use of automated CRT-based tests of colour vision in diabetic retinopathy screening protocols.

Adolescent↗