A prominent nose, the colour of the eyes, a receding chin—there are many prominent features that we use to recognise faces. But it is not only visual features that help us to identify people. Biographical background knowledge about a person also plays a major role in the processes in the brain that underlie the memorisation and recognition of people. This was discovered by psychologists at Friedrich Schiller University Jena in a new study. The scientists report on their findings in the research journal Cerebral Cortex.

Revealing study design

In order to find out how previously received information about a person influences facial recognition, the researchers divided the 45 study participants into two groups. Each group was familiarised with faces and an associated fictional biography. All participants familiarised themselves with the same faces—but the groups differed in the assignment of the respective personal knowledge. ?The same face could, for example, be associated with a strict German teacher for one group and with a charming French cook for the other group?, explains Prof. Dr Gyula Kovács from the University of Jena, who led the study.

Afterwards, all participants looked at the faces again and the Jena team used electroencephalography (EEG) to observe what was happening in their brains during this time. This revealed an individual pattern of brain signals for each face, which the researchers used to train a machine learning model. ?Through this study design, we were able to separate the influence of personal knowledge from the purely visual information contained in the face itself?, explains Gyula Kovács.

Recognition is not a purely visual process

The computer was able to recognise the corresponding faces very quickly and accurately based on the patterns—but only within a group. However, when the model was tested with patterns from the identification process of the other group, it recognised the faces significantly worse. ?In this way, we were able to show that personal knowledge strengthens identity representations in the brain—i.e. the neural pattern for a person—between 250 and 350 milliseconds after the appearance of a face—a time window that is traditionally associated with the visual processing of faces.? The background information therefore played a significant role in the identification of the respective person.

The research results indicate that recognising a face is not a purely visual process, but that our brain very quickly integrates conceptual knowledge about people with visual information, explains the Jena psychologist. ?In other words, our memories and our knowledge about people can influence how we perceive their faces. Through our study, we have learnt more about how the brain links perception and memory in social recognition.?