Does emotional expression influence face recognition? Re-examining Bruce and Young's (1986) independence hypothesis

According to (Bruce, V., & Young, A. (1986). Understanding face recognition. British Journal of Psychology, 77(3), 305-327. https://doi.org/10.1111/j.2044-8295.1986.tb02199.x), facial expression should not influence recognition memory for faces, implying that, in an old/new recognition task, expression should have no effect on discriminability, whether manipulated at encoding or retrieval. However, support for this assertion has been inconsistent. We conducted three old/new recognition experiments in which we manipulated facial expression (neutral, angry, sad, happy) at both encoding and test. In Experiment 1, we included all expressions at both study and test. In Experiment 2, we isolated the effects of expression on encoding versus retrieval by manipulating expression only at study or only at test. In our final experiment, participants were presented with only one expression at study or test, one of which was always neutral, so we could better isolate the effect of expression at the list rather than item level (e.g. study neutral faces then tested with happy faces). Overall, our experiments revealed minimal and inconsistent effects of expression on facial recognition, therefore much more research is needed to understand how (or whether) facial expression impacts recognition.