Lighting and perceived guilt

Abstract

Under six lighting conditions an "accused" was assessed for perceived guilt by observers listening to different taped evidence over headphones. The split-plot experimental design ensured that each observer heard three types of evidence about three different accused for one fixed lighting condition. A significant interaction effect was found between lighting and evidence. Subjective judgements following evidence in favour of the accused were found to be influenced by lighting. However the mean and variance of these judgements suggested the lighting had been influential when considerable observer uncertainty existed despite the apparent favourable nature of the evidence. No simple vector or scalar lighting measure could account for the results although there was evidence that perceived guilt was related to the pupil diameter of the accused under the different lighting conditions.