Measuring the impact of lighting on interpersonal judgements of pedestrians at night-time

This article discusses interpersonal judgements made between ped estrians after dark and in particular that judgements of intent are needed in addition to judgements of identity. The current study uses judgements of emotion from facial expression and body posture, and judgements of gaze direction, to evaluate the influe nce of lighting on visual cues to perceived intent. An experiment has been carried out in which judgements of emotion (using targets of facial expression and body posture) or gaze direction we re sought after 1 s exposure using nine combinations of luminanc e and interpersonal distance. Initial results for judgements of emotion from facial expression suggest a minimum luminance on the face of 0.1 cd/m 2 if facial expressions are to be recognised at 4 m, increasing to 1.0 cd/m 2 for identification at 10 m. Using these data to suggest design light levels will require further discussion as to which task is the more critical and at which distance the critical task needs to be achieved.