Explicit and implicit spatial mapping of face age

Time is often conceptualised in spatial terms. For example, concepts such as ‘before’ and ‘after’ are frequently mapped onto the left and right sides of space, respectively. Importantly, such spatial mapping typically disappears when time is processed as a task-irrelevant dimension. In the present study, we further investigated this phenomenon using highly salient and socially relevant stimuli: human faces varying in age. We conducted two experiments using the same paradigm, in which the age of a female and a male face was processed either explicitly (Experiment 1; N = 120, 50% females) or implicitly (Experiment 2; N = 120, 50% females). In Experiment 1, participants categorised the age of a centrally-presented target face as younger or older than a reference face by pressing left or right keys. In Experiment 2, participants categorised the sex of the face. Both experiments provided evidence consistent with a left-to-right spatial mapping of face age, such that younger faces tended to be associated with the left and older faces with the right, although this effect was more pronounced when age was explicitly processed (Experiment 1). Experiment 2 also revealed a spatial mapping for the sex of the face. Taken together, these findings suggest that human faces are powerful stimuli capable of eliciting spatial representations not only of time, but also of other socially meaningful dimensions, such as sex, likely due to their salience and central role in social perception.