Mean and standard errors of reaction times of pushing and pulling are illustrated in .
Mean reaction times (ms) of pushing and pulling a lever in response to emotional expressions (a) and mean reaction times of both pushing and pulling in response to male and female faces depicting emotional expressions (b).
The ANOVA showed a significant main effect for emotional expression, F(3,276) = 118.28, p < .001, η2 = 0.56, with fastest reactions to happiness followed by disgust, anger and sadness. A main effect of gender of poser, F(1,92) = 70.11, p < .001, η2 = 0.43, indicated that all participants responded more quickly to male than to female faces. There was no main effect of participant gender, F(1,92) = 1.306, ns, nor for lever direction, F(1,92) = 0.78, ns, the latter, confirming a balanced responding in the lever paradigm.
Notably, the hypothesized interaction between lever direction and emotional expression was significant, F(3,276) = 9.05, p < .001, η2 = .09, indicating differential direction for the polar emotions. The interaction between gender of poser and emotional expression reached significance, F(3,276) = 17.32, p < .001, η2 = 0.16, showing that response times differed for male and female posers depending on the specific emotion. Moreover, a trend for a gender of poser by lever direction interaction occurred, F(1,92) = 3.56, p = .062, η2 = .037, such that in response to female faces pulling was faster than pushing and in response to male faces pushing was faster than pulling.
Further elucidating the significant lever direction by emotional expression interaction, post-hoc Bonferroni-Holm-corrected paired-sample t-tests revealed that this interaction was significant for sadness, t(99) = 4.03, p < .001, d = 0.36, and happiness, t(98) = 2.52, p = .039, d = 0.25, indicating approach tendencies. Anger expressions tended to elicit avoidance behavior, t(99) = 2.02, p = .046 (corr. p = .092). For the expression of disgust the post-hoc comparison was not significant, t(98) = 1.55, p = .124.
Post-hoc Bonferroni-Holm-adjusted paired-sample t-tests to clarify the significant gender of poser by emotional expression interaction demonstrated that participants responded (irrespective of lever direction) more quickly to angry, t(96) = 8.72, p < .001, d = 0.73 and disgusted, t(97) = 6.61, p < .001, d = 0.44, male compared to female faces.
No other main effects or interactions of this ANOVA reached significance.
Mean and standard errors of response times (of both pushing and pulling) to male and female faces are presented in .
The Wilcoxon signed-rank tests on the error frequencies for each lever direction in response to every type of emotional expression did not reach significance, all ps > .40.
Rating of emotional expressions
Across all emotional expressions 13.3 % of the participants had each a standard deviation greater than 2.5, 53.5 % > 2, 75.8% > 1.8 and 92.9 % > 1.5 in their explicit responses. This result indicates that the whole scale length was used to rate the explicit approach/avoidance reaction (see for an illustration of responses).
Scatterplot of explicit ratings (mean of ratings and a line indicating mean group ratings) illustrating that the whole scale length was used for the responses. Note that equal ratings of participants are covered by only one data point.
The 2 (gender of participant) × 2 (gender of poser) × 4 (emotional expression) ANOVA with repeated measures on the rating data of the emotional expressions revealed a significant main effect of emotional expression, F(3,297) = 405.13, p < .001, η2 = 0.804, with happy faces eliciting approaching behavior, whereas sadness, disgust and anger prompted avoidance. Neither a main effect for gender of poser, F(1,99) = 2.26, ns, nor for gender of participant, F(1,99) = 0.19, ns, emerged.
Furthermore, the analysis yielded a significant interaction between emotional expression and gender of poser, F(3,297) = 36.82, p < .001, η2 = 0.27, and a significant interaction between gender of poser and gender of participant, F(1,99) = 6.70, p = .011, η2 = 0.06.
Disentangling the significant gender of poser by gender of participant interaction revealed that women, t(51) = 2.78, p = .016, d = 0.32, rated female faces more positive than male faces.
Post-hoc Bonferroni-Holm-adjusted t-tests of the emotional expression by gender of poser interaction indicated that happy, t(100) = -4.74, p < .001, d = 0.37, and sad male faces, t(100) = -3.97, p < .001, d = 0.33, were rated more positive than corresponding female faces, but angry, t(100) = 6.16, p < .001, d = 0.63, and disgusted female faces, t(100) = 5.54, p < .001, d = 0.56, were rated more positive than male faces. Mean and standard errors of the rating data across female and male posers are illustrated in .
Results of the explicit rating task displayed by male and female actors visualizing the significant emotional expression by gender of poser interaction