The influence of luminance, observation duration and procedure on the recognition of pedestrians faces

Past studies carried out to determine whether the spectral power distribution of a light source affects facial recognition have led to mixed results. One reason for this could be that different studies presented different levels of task difficulty, this being a function of target size, observation duration and type of procedure. This paper presents two facial recognition experiments carried out using matching and identification procedures to explore task difficulty as defined by observation duration and target luminance. It was confirmed that identification is more difficult than matching. A relationship between task difficulty (luminance and duration) and recognition probability was found and this allows the luminance to be determined for a given probability.