Barry L. Cole

What attracts attention when driving

Twenty-five observers were asked to report what attracted their attention while driving along a 21·9 km route through a suburban district. A second group of equal size made similar reports in the laboratory while watching a movie film of the same route. The results obtained from the laboratory trial closely parallelled those obtained in the field and it is concluded that laboratory studies using a movie simulation provide a satisfactory means of studying the distribution of attention using a concurrent verbal report technique. It is noted that the absence of a driving task has no substantial effect on attentive behaviour suggesting that the visual information presented by the movie film is sufficient to generate attentive processes characterstic of driving. It is found that advertising attracts a good proportion of attention but in those sections of the route where there was little advertising attention was directed to an even greater extent to other objects not related to driving. It seems that some 30 t...

A Field Trial of Attention and Search Conspicuity

Conspicuity might be defined as the property of an object that causes it to attract attention or to be readily located by search. It is often regarded as an attribute of the target object, but the state of attention of the observer is a factor that cannot be ignored. In this paper we define two kinds of conspicuity, attention conspicuity and search conspicuity. Attention conspicuity refers to the capacity of the object to attract attention when it is unexpected. Search conspicuity is the property of the object that enables it to be quickly and reliably located by search. A field trial was conducted to provide measures of these two kinds of conspicuity. Two groups of subjects were required to drive along a defined route on which disc targets were placed; one group was simply asked to report what attracted attention and the other was to search for and report the disc targets. The frequency with which the discs were reported was taken as a measure of conspicuity. The two kinds of conspicuity were found to be related in a systematic way. It was found that conspicuity was not strongly dependent on either object reflectance or size. An important determinant was the angle at which the object was displaced away from the line of sight.

The handicap of abnormal colour vision

All people with abnormal colour vision, except for a few mildly affected deuteranomals, report that they experience problems with colour in everyday life and at work. Contemporary society presents them with increasing problems because colour is now so widely used in printed materials and in computer displays. Equal opportunity law gives them protection against unfair discrimination in employment, so a decision to exclude a person from employment on the grounds of abnormal colour vision must now be well supported by good evidence and sound argument. This paper reviews the investigations that have contributed to understanding the nature and consequences of the problems they have.

Assessment of inherited colour vision defects in clinical practice.

Background:  Colour vision deficiency (CVD) has a high prevalence and is often a handicap in everyday life. Those who have CVD will be better able to adapt and make more informed career choices, if they know about their deficiency. The fact that from 20 to 30 per cent of adults with abnormal colour vision do not know they have CVD suggests that colour vision is not tested as often as it should be. This may be because of practitioner uncertainty about which tests to use, how to interpret them and the advice that should be given to patients on the basis of the results. The purpose of this paper is to recommend tests for primary care assessment of colour vision and provide guidance on the advice that can be given to patients with CVD.

The new Richmond HRR pseudoisochromatic test for colour vision is better than the Ishihara test

Aim:  The Hardy‐Rand‐Rittler (HRR) pseudoisochromatic test for colour vision is highly regarded but has long been out of print. Richmond Products produced a new edition in 2002 that has been re‐engineered to rectify shortcomings of the original test. This study is a validation trial of the new test using a larger sample and different criteria of evaluation from those of the previously reported validation study.

Optimum Intensity of Red Road-Traffic Signal Lights for Normal and Protanopic Observers*

Optimum intensities for a red road-traffic signal light have been determined for observers with normal and protanopic color vision. The term optimum intensity is used to mean the intensity necessary to minimize the chance of not seeing the signal and also the time of response. The experimental conditions simulated an 8-in.-diam signal light viewed from 100 m against a sky with a luminance of about 1500 ft-L. Under these conditions the optimum intensity was shown to be at least 83 cd and preferably 133 cd. Protanopes required about four times this intensity for the particular red filter used. For a sky of 3×104 ft-L luminance a red signal should have intensity of 160–260 cd. Protanopic drivers would require at least a 600 cd intensity. Surround screens were shown to improve the visibility of a red signal for normal observers only when the intensity of the signal was less than optimum.

Effect of VDUs on the eyes: report of a 6-year epidemiological study.

One thousand, three hundred and sixteen office workers [692 visual display unit (VDU) users, 624 controls in the first year] were examined once each year over a 6-year period to establish whether or not VDU work was a factor in the occurrence of visual symptoms, ocular abnormalities, or ocular disease. Statistical analysis showed that although there were differences between VDU users and nonusers in the amount of myopia, the prevalence of some symptoms, and the prevalence of signs of fundal or vitreal disease, the differences were small and there were no clear trends or patterns to lend convincing support to the hypothesis that VDU work may be a risk factor. There were no significant differences in the prevalence and incidence of cataract.

The effect of variability of background elements on the conspicuity of objects

The effect of complex backgrounds on target visibility was studied by asking observers to locate a disc target presented on a background of randomly arranged discs. A previous paper (Vision Res. 22, 1241-1252, 1982) explored the effect of increasing the density (numerosity) of the background elements when the elements were all the same size and luminance. In this investigation the size or the luminance of the background elements varied although mean size and mean luminance was held constant. Variability of the size of the background elements had a substantial effect on the size contrast necessary to detect the target. The data are well described by a contrast metric CT which assumes that observers detect the target by comparing it to a weighted average of the larger elements. The larger elements that determine the weighted average are those that all appear the same size because, at the eccentricity of target, the observers are unable to distinguish their differences in size. The threshold values of CT for detection of the target at a given level of probability were dependent on eccentricity but independent of the degree of variability of the background elements. The threshold contrast was also the same as the necessary for the more elementary task of discriminating size differences of two discs. In a second experiment it is shown that variability in the luminance of the background elements did not affect target visibility. This result is explained by reference to the data in our earlier paper from which it can be shown that the observers were unable to perceive the differences in luminance in their peripheral visual field so that, within limits, backgrounds that vary in luminance can be validly characterised by mean luminance.

Recognition of Colored Road Traffic Light Signals by Normal and Color-Vision-Defective Observers*

Normal and color defective observers were asked to identify 13 signal light colors as either red, green, or yellow under laboratory conditions simulating road traffic signals but with only chromaticity and brightness differences as cues for identification. Choice reaction times and errors were measured. A high correlation between these yields was found and each was analyzed separately. Special statistical techniques were necessary for analysis of the errors. Reaction times provided a sensitive measure and proved simpler to analyze than errors. It was concluded that the chromaticity boundaries similar to those specified by ASA D10-1 (1958) were more reliable for all classes of observers than those more liberal boundaries established by the CIE (1955) and BS:1376 (1953). None of the yellow filters proved satisfactory for color defectives. Reaction times and errors suggest that the extension of the yellow limit of the red signals in the new U. S. standard (1964) may be undesirable.

Are colour vision standards justified for the transport industry

Colour vision standards are imposed in the road, rail, maritime and aviation industries and are often subject to vigorous opposition by those excluded by the standard. With greater emphasis in recent years on equality of opportunity, it is important that standards of personal fitness, such as colour vision standards, be subject to critical scrutiny. Such appraisal should be able to demonstrate that the community benefit arising from the application of the standard is sufficient to justify the personal and other costs of retaining the standard. This paper reviews the evidence relating to colour vision standards in the transport industries and concludes that a strong case can be made for their retention in public transport.