Recognising faces seen alone or with others: When two heads are worse than one

There is a large body of work investigating face identification, but most of this addresses recognition of a single person. Here, we examine how recognition is affected by the presence of a second face. In Experiments 1 and 2, we demonstrate that memory for an unfamiliar face is severely reduced if it is seen alongside a second person. Sequential presentation of two target faces further reduces accuracy. In Experiments 3 and 4, we demonstrate the same disadvantage for two-face targets in a matching task, where subjects have no time limits or memory requirement. In matching, the damaging effect of a second face is greatest when the targets are placed close together. Furthermore, there is a general advantage for faces presented to the left. We suggest that it may not be possible to extrapolate results from single-face studies to experiments (or realistic situations) involving more than one person.