The effect of instructions and response format on smile judgement.

Our study examined the role of instructions, response type, and definition on the judgement of enjoyment and nonenjoyment smiles. Participants viewed symmetric Duchenne, non-Duchenne, and asymmetric smiles. They were instructed to judge the happiness, authenticity, and sincerity of the smiles using either Likert scales or a dichotomous response type. Participants were also either given a definition of the instruction words "happy," "authentic," and "sincere" or not. Results showed that the probability of saying "really (happy/sincere/authentic)" was higher for the symmetric Duchenne than the asymmetric smiles and higher for the asymmetric than non-Duchenne smiles. Changing the instructions given to participants did not override the effect of smile type with the use of Likert scale or dichotomous response. However, with the use of Likert scale, we observed subtilities that were not observed with the use of dichotomous response. When given a definition, in the case of symmetric non-Duchenne smiles, Likert ratings were significantly lower, and participants were more accurate in their judgement on the dichotomous scale. However, no differences were observed for the asymmetric Duchenne and symmetric Duchenne smiles whether a definition was given or not. Symmetric non-Duchenne and asymmetric Duchenne smiles were also viewed longer when a definition was given than when one was not. Nevertheless, considering methodological variations of our study failed to explain the variations in the pattern of results of previous studies, other avenues should be explored, such as the use of dynamic stimuli and a greater variety of encoders. (PsycInfo Database Record (c) 2023 APA, all rights reserved).