Lighting for pedestrians: Is facial recognition an important task for pedestrian at night?

1 January 2012

Within the street lighting community it has been argued that whilst people need light to detect obstacles along their route and orientate themselves, it is facial recognition that is a key task for pedestrians that requires the most light (Caminada and van Bommel, CIBSE National Lighting Conference 1982). However, this argument was based on assumed visual tasks and the amount of light each one required rather than any objective assessment. An eye tracking method was adopted to explore the importance of different visual tasks for the pedestrians at night. Eye tracking is a technique that has been used by many studies (e.g. Land MF, Lee D. 1994 Nature 369(6483) 742–744 and Patla AE, Vickers JN. 1997 Neuroreport 8 3661-3665) to try to understand what people are looking at a given time. Wearing an eye tracker, two groups of subjects were asked to walk three different residential routes (5 subjects in day time and 15 subjects at night). In order to obtain further information about the experience of the subjects during the walk, a short interview was performed after completion of the task. The results show that looking at other people appears to be important to pedestrians however, during this study, subjects’ fixation time on other people was limited. Also it shows that whilst pedestrians may spend between 40% and 50% of their time looking at the footpath, not all of that time is spent on critical visual tasks. Amongst the non critical visual tasks, looking at objects of personal interest was observed. The apparent importance of the visual tasks away from the footpath raises questions about the priorities in lighting of different areas for pedestrians, in particular are vertical surfaces more important than horizontal surfaces.