Mixed matters: fluency impacts trust ratings when faces range on valence but not on motivational implications

ABSTRACT

Facial features that resemble emotional expressions influence key social evaluations, including trust. Here, we present four experiments testing how the impact of such expressive features is qualified by their processing difficulty. We show that faces with mixed expressive features are relatively devalued, and faces with pure expressive features are relatively valued. This is especially true when participants first engage in a categorisation task that makes processing of mixed expressions difficult and pure expressions easy. Critically, we also demonstrate that the impact of categorisation fluency depends on the specific nature of the expressive features. When faces vary on valence (i.e. sad to happy), trust judgments increase with their positivity, but also depend on fluency. When faces vary on social motivation (i.e. angry to sad), trust judgments increase with their approachability, but remain impervious to disfluency. This suggests that people intelligently use fluency to make judgments on valence-relevant judgment dimensions – but not when faces can be judged using other relevant criteria, such as motivation. Overall, the findings highlight that key social impressions (like trust) are flexibly constructed from inputs related to stimulus features and processing experience.

KEYWORDS:

• Fluency
• trust
• face evaluation
• facial expressions
• social judgment

Acknowledgements

We thank Evan Carr and Andy Arnold for their help and research assistants at SWPS and UCSD for running the studies.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 We also found a relatively weak but significant cubic trend, F(1, 28) = 4.41; p < .05; η² = .14.

2 There was also a main effect for condition on angry-sad mixes. The expression categorisation group gave overall higher trust ratings than the control group, F(1, 231) = 25.2; p < .001; η² = .1

3 Sad-happy morphs also showed a cubic trend on affect judgments, F(1, 231) = 242.75; p < .001; η² = .51 and approach judgments, F(1, 231) = 109.99; p < .001; η² = .33. Angry-sad morphs show quadratic effects for affect judgments, F(1, 231) = 61.47; p < .001; η² = .21, and a cubic effect for approach judgments, F(1, 231) = 43.02; p < .001; η² = .16.

Additional information

Funding

This research was supported by National Science Center, Poland [grant number 2011/01/B/HS6/0335 to PW & MO] and from the UCSD Academic Senate Grant to PW.