Reversing luminance polarity: control faces are harder to recognise but easier to see

Control faces are key for understanding the extent to which performance relies on affective evaluation versus low-level image properties. Luminance polarity (LP) reversal combined with face inversion is coming an increasingly popular tool for severely disrupting control face recognition. However, recent findings demonstrate visibility-recognition trade-offs, where these control faces are advantaged in terms of salience, despite being harder to explicitly recognise. The present report brings together findings from image analysis, simple stimuli, and behavioural data for face perception, in order to provide an overview and account for why control faces subjected to LP reversal are more easily “seen” compared to other controls, and importantly, the key implications these findings have for studies of subjective face appearance, and the extent to which future research must be aware of behavioural artefacts due to trade-off effects.