Search

The purpose of this study was to investigate the effect of a self-monitoring intervention on the independent completion of dishwashing for three boys with autism (ages 6, 7, and 8) in China. The self-monitoring intervention included visual task analysis, in vivo modeling, self-recording, video self-feedback, and reinforcement. A multiple probe across subjects design was used. Prior to the study, the children had limited or no dishwashing skills, nor did they receive any training on self-monitoring. All three children acquired dishwashing and performed the task independently without supervision one week after the intervention. Their parents were very satisfied with this intervention.

Skin self-examination (SSE) consists of routinely checking the body for atypical moles that might be cancerous. Identifying atypical moles is a visual task; thus, SSE training materials utilize pattern-focused visuals to cultivate this skill. Despite widespread use, researchers have yet to explicate how pattern-focused visuals cultivate visual skill. Using eye tracking to capture the visual scanpaths of a sample of laypersons (N = 92), the current study employed a 2 (pattern: ABCDE vs. ugly duckling sign [UDS]) × 2 (presentation: photorealistic images vs. illustrations) factorial design to assess whether and how pattern-focused visuals can increase layperson accuracy in identifying atypical moles. Overall, illustrations resulted in greater sensitivity, while photos resulted in greater specificity. The UDS × photorealistic condition showed greatest specificity. For those in the photo condition with high self-efficacy, UDS increased specificity directly. For those in the photo condition with self-efficacy levels at the mean or lower, there was a conditional indirect effect such that these individuals spent a larger amount of their viewing time observing the atypical moles, and time on target was positively related to specificity. Illustrations provided significant gains in specificity for those with low-to-moderate self-efficacy by increasing total fixation time on the atypical moles. Findings suggest that maximizing visual processing efficiency could enhance existing SSE training techniques.

Electrophysiologically registered visual mismatch negativity (vMMN) is known to represent automatic visual processing in human visual cortex. Since physical activity (PA) is generally beneficial to cerebrovascular function, we wanted to find out if automatic visual processing is affected by PA. We investigated the connection between long-term leisure-time PA and precognitive visual processing in 32 healthy young males. Participants were divided into active (n = 16) and inactive (n = 16) group according to their leisure-time PA records from the past three years. vMMN was recorded with electroencephalogram using passive oddball paradigm with visual bars. Standard (90%) and deviant (10%) stimuli in different orientations were presented randomly while participant’s attention was directed to an audio play. No visual task was involved. vMMN difference waveforms were generated and peak latencies and signal integrals were determined in post-stimulus window of 100–300 ms. vMMN latencies were shorter in active part...

Given the versatility of smart phone displays, it was inevitable that applications (apps) providing colour vision testing would appear as an option. In this study, the colorimetric characteristics of five available iPhone apps for colour vision testing are assessed as a prequel to possible clinical evaluation. The colours of the displays produced by the apps are assessed with reference to the colours of a printed Ishihara test. The visual task is assessed on the basis of the colour differences and the alignment to the dichromatic confusion lines. The apps vary in quality and while some are colorimetrically acceptable, there are also some problems with their construction in making them a clinically useful app rather than curiosity driven self-testing. There is no reason why, in principle, a suitable test cannot be designed for smart phones.

Head-mounted displays (HMDs) virtually augment the visual world to aid visual task completion. Three types of HMDs were compared [look around (LA); optical see-through with organic light emitting diodes and virtual retinal display] to determine whether LA, leaving the observer functionally monocular, is inferior. Response times and error rates were determined for a combined visual search and Go-NoGo task. The costs of switching between displays were assessed separately. Finally, HMD effects on basic visual functions were quantified. Effects of HMDs on visual search and Go-NoGo task were small, but for LA display-switching costs for the Go-NoGo-task the effects were pronounced. Basic visual functions were most affected for LA (reduced visual acuity and visual field sensitivity, inaccurate vergence movements and absent stereo-vision). LA involved comparatively high switching costs for the Go-NoGo task, which might indicate reduced processing of external control cues. Reduced basic visual functions are a likely cause of this effect.

This exploratory, pilot study compared the effects of concentrating on a visual task and a very mild ocular surface air stimulus on multiple blink parameters.Ten subjects participated in this study. There were two visits, one with an ocular surface air stimulus (AS) and one without (NS). The AS was set at a level barely perceptible by subjects (approximately 0.6 m/s at the eye). At each visit, subjects performed a high-concentration (HC) and low-concentration (LC) task. Blinking was tracked and tear-film breakup (TBU) was monitored simultaneously to measure blink parameters, including the interblink interval (IBI), blink amplitude, duration, maximum velocity and TBU before and after each blink.During the HC tasks, IBI was significantly higher and blink duration was lower (repeated measures ANOVA, p0.05) than the LC tasks. The IBI in the AS-LC condition was significantly lower and less variable than in the NS-HC condition, whereas blink duration showed the opposite effect (Hotelling T² test, p0.005). There was high individual variation in correlations between blink amplitude and maximum velocity. The area of TBU was not significantly correlated with any blink parameter.The lack of correlation between TBU and blinking suggests that many blinks are stimulated by internal controls, rather than direct stimulation of the ocular surface by TBU. This pilot study suggests that even very mild ocular surface stimulation produces opposite effects on the timing and duration of the blink, when compared to concentrating on a visual task. The HC task tends to decrease blink frequency and duration, presumably to minimize interruption by the eyelids, whereas mild ocular surface AS increased blink frequency and duration, most likely to increase protection of the ocular surface.

We studied the influence of ship motion on postural activity during stance, varying stance width (the distance between the feet in side-by-side stance) and the difficulty of visual tasks. Participants (experienced crewmembers) were tested on land and then on successive days on a ship at sea in mild sea states. On land, we replicated classical effects of stance width and visual task on the magnitude of postural movement. The magnitude of forces used in postural control was greater at sea than on land. Visual performance at sea was comparable to performance on land. Both stance width and visual task difficulty influenced postural activity at sea. In addition, postural activity changed over days at sea. We conclude that experienced crewmembers modulated standing posture in support of the performance of visual tasks and that such effects occurred even in mild sea states. The overall pattern of effects is compatible with the hypothesis that postural activity is modulated, in part, in support of the performance...

Unexpected sounds have been shown to capture attention, triggering an orienting response. However, opposing effects of this attention capture on the performance of a concomitant visual task have been reported, in some instances leading to distraction and in others to facilitation. Moreover, the orienting response towards the unexpected stimuli can be modulated by working memory (WM) load, but the direction of this modulation has been another issue of controversy. In four experiments, we aimed to establish the critical factors that determine whether novel sounds facilitate or disrupt task performance and the modulation of these effects by WM load. Depending on the overall attentional demands of the task, novel sounds led to faster or slower responses. WM load attenuated novel sound effects, independent of their direction (facilitation or distraction). We propose a model by which the unexpected stimuli always generate the same orienting response but result in distraction or facilitation depending critically on the attentional focusing induced by the task at hand and the temporal relationship between the irrelevant and task-related stimuli.

To compare the locomotor capacity during (1) unobstructed walking and (2) the circumvention of fixed obstacles with and without a simultaneous visual task in an elite athlete before and after a sports-related concussion.Case report.Gait analysis and clinical neuropsychological measures were taken pre- and at 7 and 30 days post-injury in an 18 year old male junior hockey player. The task consisted of walking along an unobstructed or obstructed path with or without a visual interference task. Measurements included dual tasks costs, response errors, maximal gait speed and minimal clearance with the obstacle.Although the athlete was symptom-free and neuropsychological test results returned to baseline relatively quickly, he showed continued errors in the interference task, abnormally small obstacle clearance distances and decreased maximal gait speed up to 30 days after the concussion.Concussion can result in persistent planning and attention deficits in ecologically valid, complex environments. This report suggests that functional assessment within an ecological context could be an innovative way to evaluate concussed athletes before sending them back to play, even in the absence of medically related symptoms or abnormal neuropsychological test results.

Observers often tend to misremember the visual stopping point of a movement in the direction of movement (representational momentum). We investigated whether this forward displacement also occurs in grasping. We asked participants to close virtual pliers after the pliers had been opening or closing. The participants' thumbs and index fingers were attached to robot arms which allowed us to provide haptic feedback about the location of the pliers' handles. In a visual task, participants judged the remembered final opening width of the pliers relative to a comparison stimulus. For grasping, we found forward displacement: participants opened their fingers wider if the pliers had been opening compared to when they had been closing. In contrast, we did not find clear forward displacement in the visual task. The effects in grasping and the visual task were not correlated between participants. These results seem to argue against the existence of one form of anticipation that serves both perception and grasping.

A study was designed to test the effect of a secondary visual task on a primary visual task. In one condition, participants performed the dual-task, while assigning no weight to the secondary task. In the second condition, the primary task was performed simultaneously with the secondary task. The effect of the added workload was measured via the effect on primary task performance. In the baseline portion of the task, participants had their baseline (90% accuracy) of performance collected by adjusting the stimulus duration. The individual participant stimulus duration was then used as the experimental stimulus duration and the effect of secondary task performance on primary task performance was measured. In a third condition, practice was used as a method of controlling for individual differences. Participants performed the task as in the control condition, however they were given twice as much exposure to the task. Participants ran the study for the full duration twice. Only the performance from the secon...

Modern work activities often require an intense and prolonged visual effort on near objects. At the same time, occupational asthenopia caused by accommodation and binocularity overloading is a very common complaint in these working populations. Moreover, blinking rate seems to be a sensitive parameter with 'indoor-near-work operators', possibly increased by both chemical and physical environmental agents and decreased by cognitive effort. In this paper, a new piece of electronic equipment used to measure the observation distance and blinking rate is described.

(2001). Additivity Constraints and Visual Task Considerations in Mesopic Photometry. Journal of the Illuminating Engineering Society: Vol. 30, No. 1, pp. 90-104.

In this paper, we demonstrate that image processing algorithms (IPAs) can perform a new visual task, namely, selecting and locating regions-of-interest (ROIs). This task has been defined on the basis of a theory of human vision: the scanpath theory. Further, using the measures Sp and Ss, the similarity of location and ordering, respectively, developed over the years in studying human perception and the active looking role of eye movements, we could quantify the efficient and efficacious manner by which IPAs can imitate human vision in locating ROIs. The methodology in this paper is applied to the Mars Rover exploration.

This paper presents the case for a functional account of vision. A variety of studies have consistently revealed “change blindness” or insensitivity to changes in the visual scene during an eye movement. These studies indicate that only a small part of the information in the scene is represented in the brain from moment to moment. It is still unclear, however, exactly what is included in visual representations. This paper reviews experiments using an extended visuo-motor task, showing that display changes affect performance differently depending on the observer's place in the task. These effects are revealed by increases in fixation duration following a change. Different task-dependent increases suggest that the visual system represents only the information that is necessary for the immediate visual task. This allows a principled exploration of the stimulus properties that are included in the internal visual representation. The task specificity also has a more general implication that vision should be con...

A 12-year-old girl presented with left upper eyelid ptosis, who experienced intermittent lid contractions since birth. We noted regular cyclic movements of the upper eyelid, eyeball, and pupil. The cycle comprised periods of ptosis, exotropia, and mydriasis alternating with symmetrical eyelid position, ocular alignment, and pupillary size. The interpalpebral fissure measured 4 mm in the paralytic phase and 10 mm in the spastic phase. The pupil diameter, which was 6 mm, contracted to 3 mm in the spastic phase. These spasms last about 20 seconds. Three cycles were observed in 10 minutes. The upward gaze was slightly impaired in the paretic phase but cyclic movement in the vertical direction was not observed. The affected eye was amblyopic. The patient had voluntary control over his paretic phase when doing a close visual task. She was followed up for two years without any change.

The variations of eye fixation related potentials (EFRPs) were examined in two tasks under three lighting conditions for assessment of lighting environments. Sixteen subjects participated in two tasks; a difficult and an easy reading task under three lighting conditions: Spot light (S), General light (G) and Mixed light (M). EEG (Oz) and EOG were recorded. EEG epochs time-locked to onset of eye fixations were collected at random and averaged separately in two arrays to obtain a pair of EFRPs. Two wave forms under the S were similar, although those under the G showed the disparity, the largest disparity being in the easy task under the G. Under the S, wave forms of EFRPs were stable in the difficult task. The amplitude changed with the task load. The results suggested that EFRPs might be an index of the work load under lighting conditions.

Forty university students participated in a spatial precue task that employed foveally delivered stimuli and precues (75% validity). The influence of three factors (1) precue interval duration (200 ms, 1000 ms), (2) the level of stimulus processing required (detection, recognition), and (3) instructions (usual, augmented), upon the spatial precue effect (indexed as the RT difference between valid and invalid precue conditions) were examined. The results obtained indicated that factors (1) and (2), but not (3), exerted a significant influence upon the size of the spatial precue effect. Specifically, when the level of stimulus processing is one of ‘recognition’, a reliable spatial precue effect can be expected, regardless of precue interval duration. However, if one simply has to ‘detect’ the presence of the imperative input, a spatial precue effect will emerge if the precue interval is long (i.e. 1000 ms) but not when it is comparatively short (200 ms). These findings indicate that the ‘willingness’ of sub...

This study investigated the relationship between hypnotic susceptibility and the endogenous eyeblink with 27 subjects who were assigned to groups of high susceptibles, low susceptibles and simulators on the basis of cutoff scores from the Harvard Group Scales of Hypnotic Susceptibility: Form A and the Stanford Hypnotic Susceptibility Scales: Form C. Using a repeated-measures design, oculomotor data were collected during two separate conditions, waking and hypnotized, while subjects performed a visual task requiring the discrimination of short light flashes (200 ms) from long light flashes (400 ms). Although results partially replicated previous studies, with high susceptibles blinking significantly less than low susceptibles across both conditions, no effect was found for the hypnotic state. Failure of the simulating group to meet assumptions in the waking condition allowed no conclusions regarding impact of task demands on the endogenous eyeblink.

The use of range lights in nautical navigation involves the visual determination of the vertical alignment of two points of light, in order to indicate the centre of the channel. In two experiments it is shown that this vernier alignment task is more accurate if illuminated linear stimuli are used as range lights. Experiment 1 involved a laboratory simulation and experiment 2 involved a field test with full sized range lights. The average reduction of error through the use of linear stimuli over the standard point stimuli, for navigational alignments at a distance of one-half nautical mile from the range lights, was 69-4%. This suggests that a marked safety advantage might accrue from the use of linear range lights for nautical navigation purposes.

No clear definition of 'posture' can be found in ergonomics literature. It may be regarded as the configuration of the body's head, trunk and limbs in space or as a 'quasistatic biomechanical alignment' (Rohmert and Mainzer 1986), depending on whether the particular context in which it is used is anatomical or biomechanical. The functional aspects of posture are highlighted by the definition of a 'position adopted because it is appropriate for the task being performed' (Corlett 1981). Yet, in any work situation, functional, geometric, and biomechanical aspects are as integral to the concept of posture as they are to the consequences for performance and comfort. A simple task posture model, describing the relationships between the various factors which influence working postures, is presented as an aid to workplace design, and two examples are given to show how the model can be applied to the demands of particular types of task. An analysis is also made of the factors involved in the exertion of force, including physiological, environmental, personal, and task factors, in order to give a better understanding of the influences of task and workplace on strength capability.

We thank Lemon and Shah for their insightful comments. The finding that dopamine mediates spontaneous blink through the caudal nucleus provides the mechanism behind altered blink states in diseases such as Parkinson’s disease and schizophrenia. Fatigue has also been linked to impaired dopaminergic transmission,1,2 and it is fascinating to speculate that the changes observed in blinking could be in part centrally mediated. A local role of dopamine might also be proposed. The finding of dopaminergic nerves adjacent to goblet cells suggests a role in the regulation of these mucin-secreting cells which are critical to a stable tear film.3 Dopamine receptors have also been isolated from bovine cornea.4 Our field of study is at a crossroads between local, ocular, and central stimuli, as we challenge subjects both by desiccation of the ocular surface and by visual task to assess effects on blinking. The suggestion by Lemon and Shah to assess subjects under fixed-stare conditions is well taken. In fact, we intend to study alterations in blink patterns under various conditions of task and nontask, trying to tease out changes due to ocular dryness and those due to discomfort. It is quite possible that sympathetic dopaminergic stimulation from the stressed cornea and conjunctiva results in blinking, demonstrating its fundamental role in both central and local control of this critical function.

No physiological correlates are known for visual fatigue produced by prolonged viewing of visual display terminals (VDTs). The primary aim of the present study was to find a physiological correlate of a performance measure which is related to fatigue. The assumption was that a change in the state of fatigue expresses itself in fluctuations of accommodation. If indeed variations in accommodation are indicative of fatigue, then visual evoked potentials (VEPs) might be used for the objective estimation of fatigue, because pattern EPs are highly sensitive to the quality of the retinal image. In a realistic visual task, the VEP to pattern onset and the performance to a binary task are recorded simultaneously. Both indicators of fatigue, the amplitude of the VEP and the reaction time, proved to be sensitive to the workload of the task. If accommodation effort was increased, then reaction time increased and VEP amplitude decreased. Thus, VEPs are an indicator of the workload of a visual task. This allows compari...

The measurements were made of the muscular contractions and relaxations of accommodation (infrared optometer) and of visual evoked potential (VEP) (photic stimulation) before and after one hour's visual load, checking calculations (1800 questions/hour and 900 questions/hour). The results showed that the relaxation time in accommodation lengthened and the latency of the positive wave appearing at about 100 ms in VEP increased with the increase in visual load. In addition, the complaint rate for eye-strain was higher in the group given heavier visual work. In this group, there was no significant difference in amplitude of VEP before and after the visual task. The difference in the relaxation time before and after the visual task tended to be negatively correlated to the difference in amplitude of VEP and positively related to that in the latency. In the group given lighter visual work there were significant differences in the latency and the amplitude of VEP before and after the visual task, neither were co...

Under the present equivalent sphere illumination (ESI) system, the actual visibility of a visual task is not known. The author recommends that for every different task and viewing angle, the maximum contrast sensitivity of the task be published; thus, one can determine the ESI required for any given task in order to achieve a certain visibility, or one can obtain task visibility by knowing its ESI value. This broadens the application of the ESI system by enabling conversion between ESI and visibility for a specific task and also conversions among different tasks and viewing angles. Moreover, differences in individual contrast sensitivity response may result in different ESI and visibility from the same task, with the same viewing angle, at the same location under the same luminous environment.

Some standards for work at visual display units (VDU) recommend viewing distances of about 50 cm. The present study investigated whether or not visual strain is lower at viewing distances greater than 50 cm. Specifically, the question of whether the optimal viewing distance is determined by the individual's accommodation in a condition without fixational stimulus, the so-called dark focus, was studied. Two groups of subjects with mean dark focus of about 1 dioptre (D) and 2 D, respectively, performed a search and comparison task for 2 hours at a VDU at viewing distances of 50 cm and 100 cm. The characters on the VDU subtended the same visual angle in both conditions. Visual strain was evaluated by recording the subjects' performance during VDU work, their judgements of the comfort of the viewing distances, and their subjective estimates of visual strain; further, several oculomotor functions were measured throughout the sessions. In both groups, visual strain was higher in the 50 cm condition, and the lon...

Since the induction of the ESI system for evaluating interior lighting, there have been various metering methods developed for measuring actual lighting installations. Presently, ESI can be measured either directly or indirectly. Indirect-type measurements include such instruments as the visual task photometer and the visibility meter.2,3 Such meters determine an intermediate value such as contrast or CRF (Contrast Rendition Factor) from which ESI is calculated. Direct-type meters include ones such as the Holophane ESI meter4 and DiLaura's cylinders5 which fit over footcandle meter cells. In the first case a subjective comparison is needed for results and in the second, intermediate calculations are again required.

The relative effectiveness of five procedures for the training of individuals to perform tasks under stress was tested in a criterion situation, where subjects were requested to perform a visual search task under the threat of electric shocks. During training on the task, different groups of subjects received shocks of (a) criterion-level intensity; (b) milder than criterion-level intensity; (c) gradually increasing intensity; (d) randomly varying intensity. The last group (e) received no shocks at all. The results pointed to three conditions for the enhancement of training effectiveness: (a) minimal interference of exposure to stressors with task acquisition, (b) familiarity with stressors characteristic of the criterion situation, and (c) absence of unrealistic expectations about future stressors. However, none of the five training procedures meets all three conditions. Implications for the design of procedures whereby persons can be trained to perform proficiently under stress are discussed.

At workplaces with optical aids workers complain more often from visual and musculo-skeletal disorders compared to those working in offices. These complaints concern more often workers using magnifying glasses than those using stereomicroscopes. Bad working-postures at workplaces with loupes and the worse optical quality of todays loupes are two causes. In addition, the measured magnification was less than the theoretical value of standards. The strain of accommodation was high. The results of this study suggest use of eye-glasses for near-vision in addition to loupes. The use of stereo-microscopes instead of loupes must be recommended.

Many of the results obtained with this test program indicate that simple procedures may not give results on the effect of loss of contrast that are truly meaningful. The visual task evaluator results were disappointing but confirmed the findings that consistency of results varied with different operators. In the author's experiment, a large number of operators making large numbers of readings showed a significant variation which gives further evidence that the operator is a problem.

READING IN any situation where there is vibration of the reading material, as on a train, is apt to become an annoying experience. It would seem that the blurring caused by the vibration introduces a se vere visual task that may induce visual fatigue. In an initial experi ment, Tinker (4) found that vibration retarded speed of perception by 5.19 percent when reading 10.point book type. This was a significant reduction in efficiency. The typography involved was an optimal printing arrangement. The question arises whether the deleterious effects of vibration are increased when the typography is non-optimal. The specific problem in this experiment is to investigate the effect of vibration upon speed of perception while reading material printed in six point Roman (ordinary type) and six point italic type.

Two experiments were performed to determine whether groups trained on a visual meter-watching task with knowledge of results (K-R) would detect more signals than a control group trained without KR in a later session in which a different watchkeeping task was used. The transfer tasks in the two experiments consisted of detecting a brief interruption of (1) a continuously illuminated light, and (2) a pure tone mixed with continuous white noise. The group trained with KB did significantly better (p

Accuracies obtained for the visual task of pointing or centring a circular black measuring mark on a circular bright target are presented. To understand the complex pattern of pointing accuracies, the shape of the image actually seen by the visual system is computed. This is performed by convolving the luminance profiles of the targets with point spread functions of the visual system, which estimate effects of image blur and lateral inhibition. The resulting luminance profiles are then analysed and simple visual criteria on which the pointing task is based are derived.

The distributions of the interval of saccadic movements during different visual situations were analysed. These distributions were composed of three kinds of movement which have different properties; involuntary, voluntary and fixation. Involuntary movements occurred when a subject ran his eyes along a line, or when he searched some targets on an object. Also, corrective movements to a fixation point were considered as involuntary. The interval of these movements was less than 270 msec. When the subject voluntarily moved his eyes among targets in succession, the intervals were distributed from about 270 msec to 500 msec. In the case of more than about 500 msec, the subject gazed at a target carefully, or he was not required to see any special object. From those results, a side view of a visual task may be inferred from an analysis of the interval of saccadic movements. Furthermore, a criterion for the estimation of the load of a paced visual task, such as an inspection task on a conveyor belt, ma...

An experiment is reported on the times taken to porceive accurately two Landolt rings undor conditions requiring a chango of accommodation from a far to a near distance, to determino whether thero is any inereaso in this time aftor performing a prolongod visual task. This experiment was part of a study of mothods of moasuring visual fatigue. Measurements were made on oight students before and after two-hour periods of sotting a vornier gauge under two different levels of illumination (1 lm/ft2 and 30 lm/ft2). Thero was a significant increase in average time required if the two lovcls of illumination wore considered together. Change of time required did not diffor significantly between the two different lovols of illumination of the vornier gaugo during setting. Contrary to eortain provious work, no average rise in variance of the settings of the vornier gauge was found during the two-honr periods ovor which tho task was continued

THE INFORMATION NECESSARY FOR MAKING A COMPARISON BETWEEN HIGH PRESSURE SODIUM LAMPS AND EARLIER AVAILABLE TYPES OF LIGHT SOURCE IS PROVIDED. THE ECONOMICS OF LIGHTING INSTALLATIONS OF DIFFERENT LIGHT SOURCES ARE COMPARED AND THE COMPARISONS ARE BASED ON INTERNATIONALLY RECOGNIZED OPINIONS ON THE QUALITY OF LIGHTING FOR ROADWAY TRAFFIC. THE RESULTS OF A SERIES OF INVESTIGATIONS ON COLOR ARE PRESENTED. THESE PROVIDE INFORMATION ON THE LIGHT FROM INCANDESCENT LAMPS, HIGH-PRESSURE AND LOW-PRESSURE MERCURY LAMPS, FLUORESCENT LAMPS AND LOW AND HIGH PRESSURE SODIUM LAMPS (LPS AND HPS). IN A FIRST SERIES OF OBSERVATIONS, VISUAL PERFORMANCE WAS MEASURED USING LANDOLT RINGS AS THE VISUAL TASK. DETAILS ARE GIVEN OF THE METHOD OF INVESTIGATION, AND CONCLUSIONS DRAWN FROM ANALYSIS OF THE RESULTS ARE PRESENTED. A SECOND SERIES OF OBSERVATIONS (MADE IN THE LABORATORY) AIMED AT THE COMPARISON OF GLARE FROM PUBLIC LIGHTING OF DIFFERENT COLORS, BUT WHICH OTHERWISE HAD IDENTICAL PHOTOMETRIC CONDITIONS. OBSERVERS STUDIED A PHOTOGRAPH WHICH COULD BE LIGHTED HOMOGENEOUSLY, ALL OVER ITS SURFACE BY EACH OF THE SETS OF LAMPS INVOLVED IN THE TESTS. THE LUMINANCE RATIOS OF THE ROAD SURFACE AND ITS IMMEDIATE SURROUNDINGS, AS SEEN IN THE PHOTOGRAPH, WERE NEARLY EQUAL TO THOSE WHICH WOULD BE ACTUALLY SEEN BY A DRIVER ON THE ROAD ITSELF FROM THE POINT FROM WHICH THE PICTURE WAS TAKEN. FURTHER DETAILS OF THE EXPERIMENT ARE GIVEN. SIMULATED ROAD LIGHTING INSTALLATIONS WERE AGAIN USED FOR THE PURPOSE OF COMPARING THE THREE COLORS OF LIGHT WITH THE APPARENT BRIGTHNESS OF THE ROAD SURFACE. THE RESULTS OF EXPERIMENTS ARE TABULATED AND GRAPHICALLY REPRESENTED. THE CONCLUSIONS DRAWN WITH RESPECT TO THE COMPARISON OF LPS LIGHT WITH OTHER TYPES OF LIGHT INVESTIGATED (HIGH PRESSURE MERCURY WITH FLUORESCENT AND CLEAR BULB, FLUORESCENT WITH INCANDESCENT) ARE SUMMARIZED. LUMINANCE LEVEL, ITS UNIFORMITY, AND THE LIMITATION OF GLARE ARE THE CRITIERIA CONSIDERED IN A COMPARISON OF THE ECONOMICS OF DIFFERENT LIGHT SOURCES. THE PRICES OF VARIOUS LUMINAIRES ARE TABULATED AND THE INFERENCES MADE ARE DISCUSSED. IN A DISCUSSION WHICH FOLLOWS, THE ASPECTS CONSIDERED INCLUDE TESTS ON THE COLOR OF LIGHT AND VISUAL ACUITY, THE LONG LINEAR LOW LUMINANCE ARE SOURCE, THE HIGH LUMINOUS EFFICACY OF THE SOURCE, AND EUROPEAN ROADWAY LIGHTING STUDIES.

Management may decide to use vision screening to assist in selection of personnel, or as a step in the provision of better vision for employees. There are difficulties in analysing the relationships between visual abilities and job, competence and management should consult vision experts when considering the matter. Before commencing a vision screening programme the job's visual task should be analysed and the importance of the various visual parameters assessed. Vision can be screened by a modified clinical technique or with instrumental screeners. A number of instrumental screeners are described here. Results from instrumental vision Screening have good reliability and fairly good validity. For jobs of high visual demand or where vision is crucially important a modified clinical technique should be used for screening.