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36Chapter 2symmetrized vs. asymmetrized) and Probe Location (behind symmetrical/behind asymmetrical face). Furthermore, in contrast to Experiment 1and 3, this experiment did not include a stimulus validation.ResultsSimple modelTo test our main prediction that facial symmetry would significantly influence RT, we ran a Bayesian mixed model with by-subject mean-centered RTper trial as dependent variable, and the interaction between Condition andProbe Location as independent variables (see Table 2). We found no effectof facial symmetry on reaction time in any of the three conditions (see Figure 4); in each condition the differences in RT between the probe locationswere negligible (asymmetrized vs. original: median difference = -1.01 [3.05],89% CI [5.92, 3.82], pd = .63; symmetrized vs. original: median difference =0.99 [2.91], 89% CI [-3.66, 5.66], pd = .64; symmetrized vs. asymmetrized:median difference = 1.67 [2.97], 89% CI [-3.14, 6.32], pd = .71).Age and SexWe investigated whether adding either Age or Sex to the model did improvethe predictive accuracy relative to the simple model. Both the model including Sex (∆elpdLOO = 4.4 [1.7]) and the model including Age (∆elpdLOO= 0.5 [2.9]) had a slightly lower predictive accuracy than the simple model.Altogether, this suggests that including age or sex did not improve the predictive accuracy of the model.Experiment 3MethodParticipantsExperiment 3 included 150 new participants (73 females, mean age = 30.98years old, SD = 12.65, ranging from 18 to 70 years old). Participants werevisitors at the Apenheul Primate Park (Apeldoorn, The Netherlands). Allparticipants self-reported normal or corrected-to-normal vision and were heterosexual. The experimental procedures were in accordance with the Declaration of Helsinki and the study was reviewed and approved by the Psychology Ethics Committee of Leiden University (CEP18-0531/272). Participantswere not compensated for their participation.Iliana Samara 17x24.indd 36 08-04-2024 16:35