To establish optimal lighting for inter-personal evaluations between pedestrians it is desirable to know what visual cues are used. An experiment was conducted to test two proposals. One, the widely made assumption (in lighting research) that the face is an important cue. Two, the hierarchy of factors proposed by a lighting designer. This was investigated using category rating with a series of images containing actors embedded into an outdoor scene.
This study concerns road lighting for pedestrians. Many experiments have been conducted to determine how changes in lighting affect the ability to make interpersonal evaluations, usually considering variations in light level or light spectrum. Here, we consider an alternative approach, predicting performance using an existing model, Relative Visual Performance. The results show that face evaluation ability is affected by adaptation luminance, pavement surface reflectance, observer age, and skin tone of the observed person. Previous experimental studies have tended to use young test participants to evaluate Caucasian or Asian faces: if the situation instead involved an elderly person evaluating a face of South African skin tone, then the current analysis predicts that for optimal performance the light level would need to be doubled.
Pedestrians need to be able to evaluate other people to support their feeling of safety. While past studies have thus investigated the degree to which road lighting supports facial identity and facial emotion evaluations, it is not yet known whether the face is the most important visual cue. Following a pilot study that indicated the importance of the ability to see the face and hands of other people, an experiment was conducted in which test participants evaluated safety when shown photographs of an approaching person in night-time scenes. These photographs displayed variations in the exposure or concealment of the face and hands. Two procedures were used, category rating and paired comparisons. The results suggest that the face is a more important visual cue than the hands for pedestrians’ evaluations of the intent of other pedestrians after dark.
In subsidiary roads, lighting is installed to meet the needs of pedestrians after dark for safety and their feeling of safety. One aspect is the need to evaluate other people to inform the approach-or-avoid decision. To investigate how changes in lighting matter for this task, we first need to know where people tend to look. Much past work assumes the face is the critical target but this assumption has yet to be tested. A pilot study suggested ability to see the hands and face were significant cues, but did not enable their separate contributions to be identified. This paper describes a second experiment conducted to compare the effect of changes in face and hand concealment on evaluations of safety. The results suggest significant differences between levels of face concealment but smaller differences for changes in hand concealment. The findings from both experiments support the importance of the face for evaluating other pedestrians.
In research of lighting for pedestrians, many experiments have been conducted to determine how changes in lighting affect the ability to make interpersonal evaluations. Here we consider an alternative approach, predicting performance using a model - Relative Visual Performance. The results show that face evaluation ability is affected by adaptation luminance and also by personal characteristics; observer age and skin tone of the observed person. While 2 lx is sufficient for a young observer to evaluate a Caucasian face, the typical situation in laboratory trials, higher illuminances are needed for older observers and for darker skin tones.
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