From facial recognition to the recognition of facial expressions: A full-scale laboratory study

Outdoor lighting makes public space accessible after dark and aims to improve the safety of pedestrians. A systematic literature review shows that facial recognition is the most relevant visual task for judging the potential threat of other pedestrians. In the identified literature it has been operationalized as the task of recognising gender; guessing identity or seeing facial features. However, facial expressions might be of greater importance for perceived safety. As a subsequent step to the literature review, recognition of facial expressions was explored in a full-scale laboratory containing a pathway and two luminaires (18 m apart). The participants (n=91, age: 20-75, 52% women) walked along the footpath under three different lighting designs (2 LEDs and 1 CMH) and stopped when they could make out the expression in a photograph of a woman’s face (175x200 mm; placed at the height of 1.65 m). The facial expressions depicted; (fear, surprise and anger, from P. Ekman’s Emotions Revealed photo set) were assessed on 11 emotions graded by a 5-point Likert scale. Data will be statistically analysed to identify any differences in recognised facial expressions due to variations in illumination, scotopic/photopic-ratios and glare. The outcome will inform lighting designs for pedestrians in urban areas