| Abstract: |
Previous research on the relation between oxytocin and trustworthiness
evaluations has yielded inconsistent results. The current study reports an
experiment using artificial faces which allows manipulating the dimension of
trustworthiness without changing factors like emotions or face symmetry. We
investigate whether (1) oxytocin increases the average trustworthiness
evaluation of faces (level effect), and/or whether (2) oxytocin improves the
discriminatory ability of trustworthiness perception so that people become
more accurate in distinguishing faces that vary along a gradient of
trustworthiness. In a double blind oxytocin/placebo experiment (N = 106)
participants conducted two judgment tasks. First they evaluated the
trustworthiness of a series of pictures of artificially generated neutral
faces. Next they compared neutral faces with artificially generated faces that
were manipulated to vary in trustworthiness. The results indicate that
oxytocin (relative to a placebo) does not affect the evaluation of
trustworthiness in the first task. However, in the second task,
misclassification of untrustworthy faces as trustworthy occurred significantly
less in the oxytocin group. Furthermore, oxytocin improved the discriminatory
ability of untrustworthy, but not trustworthy faces. We conclude that oxytocin
does not increase trustworthiness judgments on average, but that it helps
people to more accurately recognize an untrustworthy face. |