1.1. Aims of the present study
Our overarching aim was to investigate how changes of the N250 component
in ERPs to faces across repeated exposures are associated with face
memory/recognition abilities on the individual differences level. More
specifically, we distinguished between an easy versus a difficult test
of face memory, following the distinction established by Wilhelm et al.
(2010). Due to limit testing time, we measured face memory/recognition
on a manifest rather than a latent level. ERPs, in particular the N250,
were derived in a paradigm first employed by Tanaka and colleagues
(2006). In this paradigm, a designated target face is presented,
randomly mixed with several initially unfamiliar nontarget faces and the
own face of the participant. As a novelty, the nontarget faces in the
present study consisted of two sets of high- and low-distinctive
unfamiliar faces, as determined by an independent sample of raters.
On the group level, we tested the N250 amplitudes for changes from the
first to the second half of the EEG session, expecting to replicate the
increase for target faces reported by Tanaka et al. (2006) and Sommer et
al. (2021). We also tested this change across session halves in the N250
to the non-target faces and differentiated between high- and
low-distinctive faces. On the individual differences level, we
correlated the ERP differences between the first and second half of the
session for the N250 to target faces, and to high- and low-distinctive
non-targets faces with the performance estimates from the two memory
tests. We expected more negative N250 amplitudes in the second half of
the experiment to go along with better face memory/recognition. It was
of special interest to study how this relationship depends on the
target-status and the distinctiveness of the N250-eliciting stimuli and
on the difficulty of the memory test.
2. Methods
The study consisted of a single session with two parts, a psychometric
part, employing a test from the test battery of Hildebrandt et al.
(2010) in a speed and an accuracy version and an EEG part modelled after
the study of Tanaka et al. (2006). We always conducted the psychometric
part first, followed by a break of 40 minutes before the EEG part
started.