The authors investigated the role of dissimilarity on context effects in person perception. Most research predicts similar people to be similarly evaluated and different people to be contrasted with each other. However, some research suggests that similarity may enhance comparison and contrast. To explain these opposite effects, the authors argue that dissimilarity may influence 2 different processes with opposite consequences. Dissimilarity may decrease common categorization and thus the likelihood of comparison, resulting in reduced contrast, whereas during comparison itself dissimilarity may increase the perceived dissimilarity of features and thereby increase contrast. To investigate this, the authors conducted 3 studies in which they manipulated dissimilarity by inserting morphs that were related or unrelated to the context and target faces before judgments were made. The results indicate that dissimilarity may affect the likelihood and the outcome of comparison, with contrasting consequences.
Ruys, K. I., Spears, R., Gordijn, E. H., & de Vries, N. K. (2006). Two faces of (dis)similarity in affective judgments of persons: contrast or assimilation effects revealed by morphs. Journal of Personality and Social Psychology, 90(3), 399-411. https://doi.org/10.1037/0022-35220.127.116.119