4.2. ERPs
Extending reports of Tanaka et al. (2006) and Sommer et al. (2021), the
N250 to target faces was larger in the second than in the first part of
the experiment. The N250 has been related to facial representations at a
certain level of abstraction (Wiese et al., 2021) and the increase
across the experiment likely reflects the increasing build-up of these
representations. Since our stimulus materials consisted of Asian faces
and our participants were Chinese students, the results indicate the
culture independence of this increasing face representations.
Interestingly, also the non-target elicited N250 increased from the
first to the second half of the experiment. The non-target faces did not
have to be explicitly identified at an individual level but only had to
be rejected as not being the target face. These results go beyond
findings of both the studies of Tanaka et al. (2006) and Sommer et al.
(2021), which did not find such effects in the N250 amplitude to
non-target faces. We presume that a crucial factor in bringing out the
N250 effects to non-targets is the nature of these faces. In contrast to
the previous studies, we had controlled the stimulus materials for
distinctiveness and can therefore claim that the target face was of
low-distinctiveness. Low-distinctive target faces are likely harder to
recognize than high-distinctive target faces (e.g., Light et al., 1979).
Therefore, it is possible that in order to detect the target face, our
participants were forced to scrutinize the non-target faces more than
the participants of the previous studies and therefore encoded them
incidentally. Attention to a stimulus is a crucial factor in memory
encoding.