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Andrew Freedman, Gordon E Legge; Effect of enhanced lighting on detection of targets with artificially reduced acuity. Invest. Ophthalmol. Vis. Sci. 2021;62(8):3579.
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© ARVO (1962-2015); The Authors (2016-present)
To design visually accessible spaces, it is important to understand how illumination and target-background luminance contrast affect detection of key features in the environment. Simply increasing overall room illumination ignores the crucial role of contrast in determining visibility, and directional lighting may reduce the contrast between an object and its background. This study examined the effects of illumination and luminance contrast on the detectability of objects in the environment for those with reduced acuity.
13 normally sighted subjects, wearing blur goggles that reduced their acuity to approximately 20/900, completed a visual search task. Under typical ambient indoor lighting, subjects walked along a path, following a guideline, and visually searched for targets adjacent to the path. Subjects verbally identified the shape of targets as they walked. Performance was quantified with detection rate, the percent of targets subjects attempted to identify. Targets were white or grey Styrofoam objects on the floor, in a room with walls painted white or black. Spotlights were used to increase the illumination of targets placed against the walls to three fold their ambient illumination, creating two lighting conditions: ambient and enhanced. This served to either increase contrast (e.g. grey targets against black walls), or decrease contrast (grey targets against white walls). This created targets with high or low contrast with their background under both lighting conditions, for independent manipulation of both lighting and contrast. A multiple binomial logistic regression was performed to analyze the probability that a target would be detected.
The model was statistically significant (χ2(3)=92.89, p<.001), and showed that detection odds were significantly increased by 3.41 fold for high vs low contrast targets (CI =1.80-6.44; p<.001). While increased illumination significantly increased detection rate by 29.2% for grey targets against a black background (CI=10.4-48.1%; p=.006), it did not significantly improve performance under other conditions, and was not statistically significant in the model.
Under low-acuity conditions in the environment tested here, luminance contrast was more predictive of object detectability than illumination. Notably, in some cases, increased illumination from directional lighting enhanced detectability by increasing target-background contrast.
This is a 2021 ARVO Annual Meeting abstract.
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