Neural correlates of familiar face recognition do not benefit from colour information

Humans are highly efficient at recognizing familiar faces. This remarkable ability is based on image-invariant long-term representations of known faces which can be activated from highly variable instances, including pictures that have never been seen before. While the existence of such representations is well-established, it is less clear what specific information is stored in them. Here, we examined whether colour information is beneficial for activating familiar face representations, which would suggest that they contain such information. We used event-related brain potentials (ERPs) in an immediate repetition priming paradigm. Images of well-known celebrities were combined into prime/target pairs, consisting of either different images of the same facial identity (repetition condition) or two different identities (non-repetition condition). Critically, while the target face was always presented in colour, the prime could be either in colour or greyscale. We observed clear ERP priming effects, with more negative amplitudes at occipito-temporal channels in the repetition relative to the non-repetition conditions starting approximately 220ms after target onset. This N250r effect was highly similar for colour and greyscale primes. These findings show that face representations are efficiently activated by both colour and greyscale images, and accordingly that colour information is not beneficial for facial identity processing. This is in line with the suggestion that familiar face representations do not contain colour information.