Continuation of Visual-Field Mapping for a Target Embedded in a Regular Background

The binocular functional visual-field, which is the area around the fixation point within which a target can be detected, was mapped for two subjects, using a peripherally presented target in a regular background. Over-all the field shapes were strikingly similar to field shapes reported previously for these two subjects and confirmed the presence of boundary irregularities for both subjects.

Reproductive parameters of rhinobatid and urolophid batoids taken as by-catch in the Queensland (Australia) east coast otter-trawl fishery

Reproductive variables are provided for batoids regularly taken as by-catch in the east coast otter-trawl fishery on the inner-mid continental shelf off the south-east and central coasts of Queensland, Australia. Total length at maturity (LT50 and 95% c.i.) for the eastern shovelnose ray Aptychotrema rostrata was 639·5 mm (617·6-663·4 mm) for females and 597·3 mm (551·4-648·6 mm) for males. Litter size (n = 9) ranged from nine to 20 (mean ± s.e. = 15·1 ± 1·2). This species exhibited a positive litter size-maternal size relationship. Disc width at maturity (WD50 and 95% c.i.) for the common stingaree Trygonoptera testacea was 162·7 mm (155·8-168·5 mm) for females and 145·9 mm (140·2-150·2 mm) for males. Gravid T. testacea (n = 6) each carried a single egg in the one functional (left) uterus. Disc width at maturity (WD50 and 95% c.i.) for the Kapala stingaree Urolophus kapalensis was 153·7 mm (145·1-160·4 mm) for females and 155·2 mm (149·1-159·1 mm) for males. Gravid U. kapalensis (n = 16) each carried a single egg or embryo in the one functional (left) uterus. A single female yellowback stingaree Urolophus sufflavus carried an embryo in each uterus. A global review of the litter sizes of shovelnose rays (Rhinobatidae) and stingarees (Urolophidae) is provided.

Safety and ergonomics evaluation of hybrid systems in Hong Kong

This study is aimed at understanding common safety and ergonomics problems with robot installation in Hong Kong. Information was collected through direct observations and personal interviews with robot users from advanced hybrid manufacturing systems. The application areas of robots and types of safety devices employed were investigated. The ages, types of jobs, daily working hours and working conditions of personnel were examined. Fire precaution measures, types and varieties of training programs for users were analyzed. The results showed that although investments were made for installation of robots for improving production activity, limited attention was paid to the health, safety, and ergonomics aspects in the hybrid systems. There were also cases reported where no formal guidelines for robot manipulation and operation were provided. It seems that management and users paid attention to robot function and capability more than robot safety during robotization process. Conclusions were made by the authors that efforts should immediately be made to adopt recommendations on the safety devices and facilities and training requirements for improving users' health and safety before fatal accidents occur.

A study of the discriminability of shape symbols by the foot

An experiment to test the discriminability of shape symbols using the shod foot was performed with 38 blind people (aged 23-72 years). Ten shape symbols which were 5 mm thick and fitted into a 30.5 cm2 tile were presented to subjects to identify by using only their feet. Each subject had 20 trials in which to discriminate the symbols. In each trial, a symbol was selected randomly and presented to the subject in randomized orientation. The subject was instructed to step on the symbol and to identify it using their own method. Time to discriminate a symbol and the accuracy of identification were recorded. A very high accuracy (93% on average) was obtained, which is comparable to the accuracy of tactile symbol discrimination using the hands. Average time to discriminate a symbol was 16 s with a standard deviation of 12.15 s, which indicated the high variability of the results. Owing to the high accuracy of identification, tactile foot-discriminable symbols have great potential as landmarks for blind people and if applied to a tactile guide path they could provide information for orientation and navigation.

Stimulus size scaling and foveal load as determinants of peripheral target detection

This paper reports two experiments on the effect of scaling the size of stimuli (using factors derived from consideration of cortical magnification) on the detection of peripheral visual targets. In the first experiment two levels of magnification, fully M-scaled and half M-scaled, were used to scale stimuli that were presented briefly. The performance decrement normally associated with increasing retinal eccentricity did not occur with both levels of magnification. There was an unexpected decline in performance at low eccentricities and possible explanations are discussed. The second experiment investigated the effects of half M-scaling on a peripheral detection task with the addition of foveal cognitive loading as would be found in many practical tasks. Half M-scaling improved performance with and without the presence of foveal loading, and the improvement was greater for the foveal load condition when the target was at the larger eccentricities. These results provide a useful indication of the possibility of reducing the effect of tunnel vision for visual inspection tasks on visual displays or, possibly, control panels through the development of variable resolution projection displays matching the psychophysical properties of the human visual system.

Revising and validating the random search model for competitive search

A random search model was fit to a total of 2592 visual search times on a single-target detection task. By using a competing homogeneous background and uniform stimulus material, specifying viewing distance, controlling the presentation of search task material, and eliminating some options for extreme search strategies, very high correlation coefficients were found when a random search model was fit to both the individual data and to pooled data. A response time parameter was incorporated into the traditional random-search model and very good predictions of search performance were obtained.

Visual search performance with complete and incomplete visual lobe areas

A simulation study of the effects of visual lobe shape and search strategy on search performance is reported. Using a homogeneous pattern search task that did not dictate eye fixation movements (as in reading), three basic categories of strategy and two lobe shapes were tested. Random strategies with controlled overlap of lobe areas, representing various degrees of memory, were found to produce better performance (faster search times with equal or better detection rates) than either a completely random strategy or systematic strategies with various degrees of controlled visual lobe area overlap. The controlled overlap random strategies were far better able to compensate for non-optimum interfixation distances and distortion of visual lobe shape than systematic strategies.

Effects of priority assignment of attentional resources, order of testing, and response sequence on tunnel vision

The effects of relative priority of attentional resources allocated to simultaneous peripheral and foveal tasks, response sequence to the tasks, and order to testing with two levels of foveal cognitive loading on tunnel vision were studied with 32 Chinese undergraduates. Two levels of foveal condition were used for the foveal task while the peripheral task required a single-target detection. Performance decrement value and a significant interaction of levels x eccentricities indicated that tunnel vision was most prominent when the foveal task was primary. Greater magnitude of tunnel vision was obtained when the more difficult foveal task was tested prior to the no-foveal-load condition. Responding sequence to the tasks was nonsignificant.

The effect of scale-side, indicator type, and control plane on direction-of-turn stereotypes for Hong Kong Chinese subjects

This study investigates the influence of scale-side, pointer type, direction-of-increase, and control plane on direction-of-turn stereotypes for Chinese subjects using a variety of configurations of a linear display with a rotary control. Pointer type and direction of increase did not have a significant effect on direction-of-turn expectation. Strong stereotypes are found when Warrick's principle and the scale-side principle do not clash. In such a configuration, the scale is on the opposite side of the display to the control, and the display indicator moves in the same plane as the control. However, when the two principles clash, stereotypes are weakened or eliminated and no single principle dominates. For a rotary control placed to the right of a horizontal linear scale in the frontal plane there are strong clockwise-for-right and counterclockwise-for-left stereotypes which dominate the scale-side principle when there is a clash. The most marked stereotypes and fastest response times are obtained for the horizontal display with the control in the same frontal plane.

Visual lobe area mapping for targets on a competing homogeneous background

Binocular visual lobe areas for two subjects were mapped over part of the visual field. Overall, the lobe shapes were strikingly consistent over a period of 18 months with regard to boundary irregularities and regions of insensitivity. The ratio of eight-axis mapping area to eight-axis area based on complete mapping data was near unity for one subject but very much higher for the other. If these results are typical, the various methods of determining lobe area from measurements taken on a few axes can only give very approximate relative values. It was suggested that the irregular boundary and areas of insensitivity may partly account for the difficulty some subjects experience in locating targets during visual search, even after repeated scanning.

Effects of cognitive foveal load on a peripheral single-target detection task

This experiment investigated the effects of foveal cognitive load on a primary peripheral single-target detection task. Four levels of foveal task with cognitive loads involving identification and summation of numerals were used. Number of correct targets detected seemed unaffected by the foveal load in the near periphery but a decrement occurred beyond 7.7 degrees. Response times for correct responses showed large dispersion compared with that for correct locations. At a low cognitive load, foveal task performance showed no deterioration for all eccentricities tested, but at a higher cognitive load performance declined gradually across eccentricities. Mild evidence of tunnel vision was obtained as indicated by the significant interaction of cognitive loads x eccentricities. Resources theory accounted well for the results.

Inter-relationships between visual lobe dimensions, search times and eye movement parameters for a competition search task

The inter-relationships between visual lobe dimensions, search times and eye movement parameters were investigated for a competition search task with 18 subjects. The subjects had previously participated in a visual lobe measurement and two search performance experiments using the same set of stimulus material. Using an Eye Mark Recorder, the average search times of subjects were found to be comparatively longer than for previous search tasks not using the recorder, and relative search performance ranks of the subjects were altered. The method of stimulus presentation and the search area were different in this experiment, so we cannot be certain as to which factor or factors caused the lengthening of search times and changes in ranking. All subjects achieved a 100% hit rate with no mis-classification of targets. A very high correlation coefficient was obtained for cumulative detection percentage and pooled search times when fitted to a random search model. Average search times were found to be significantly correlated with fixation durations as well as with the number of fixations. Contrary to expectation, none of the visual lobe dimensions was found to correlate significantly with average search times nor with eye movement parameters.

Strength of stereotype and response time for linear displays and rotary controls

101 Hong Kong Chinese subjects were tested on six configurations of linear displays and rotary controls. A significant linear relationship was found between the average response times and the strength of direction-of-turn stereotype as measured by the proportion of response made by the majority of subjects.

Continuation of visual-field mapping for a target embedded in a regular background

The binocular functional visual-field, which is the area around the fixation point within which a target can be detected, was mapped for two subjects, using a peripherally presented target in a regular background. Over-all the field shapes were strikingly similar to field shapes reported previously for these two subjects and confirmed the presence of boundary irregularities for both subjects.

The design of school furniture for Hong Kong schoolchildren. An anthropometric case study

Anthropometric data of Hong Kong schoolchildren have been collected and analysed in order to develop recommendations for the design of chairs and tables for use in Hong Kong Government coeducational schools. The anthropometric data for Hong Kong have been compared with data from a Western population (United Kingdom) and another Asian population (Japan). Five sizes of chair and table combinations have been proposed to accommodate six primary and seven secondary forms (pupils aged from 6 to 18 years). The recommended design dimensions, based on the anthropometric characteristics of the Hong Kong target populations, are discussed in relation to recommendations from previous research in this area.

Mapping the binocular visual field for a target embedded in a regular background

The binocular functional visual-field, which is the area around the fixation point within which a target can be detected, was mapped, for two subjects, using a peripherally presented target in a regular background. The field boundaries were very irregular, there were regions of insensitivity within the field areas, and there were differences between the subjects. It was suggested that the irregular boundary and areas of insensitivity may have important implications for mathematical models of visual search. Individual visual-field characteristics may partly account for the difficulty experienced by some people in locating targets even after repeated scanning.

Anthropometry of the Hong Kong male and the design of bus driver cabs

This study investigated the proposition that the crabs of buses imported into Hong Kong were not suited to the anthropometric characteristics of the local Chinese bus drivers. A 'recommended' cab design was derived from static anthropometric data; relationships between pedals, steering wheel and seat, and the range of seat adjustments were specified. Overall static anthropometric data were available but additional data had to be estimated by constructing manikins based on the available Hong Kong static data with joint positions derived from data for the US male population. Seven bus cab designs in current use were compared with the ' recommended' design. None of them satisfied all the 'recommended' design specifications, the most serious deviations being the excessive height of the seat above the floor and pedals, and insufficient lateral separation between the pedals.

Eight-axis visual-field mapping for targets embedded in a homogeneous competing background

The binocular functional visual field for a detection task, with a peripherally presented target embedded in a homogeneous competing background, was mapped on 8 axes passing through the fixation point. The boundary of the field for each axis was based on the number of "correct" responses on the axis, where a "correct" response was defined in terms of the size of the error made by the subjects in estimating the target position. The visual fields for 6 subjects (4 men and 2 women) were very irregular in shape, and these were differences among subjects. The 8-axis area correlated highly with area based on only the horizontal and vertical axes but the latter area gave no indication of even gross irregularities in shape of the visual field.