Similarity judgements: the comparison of normative predictions and subjective evaluations - A study of the ratio model of similarity in social context

Introduction

This study examines the consistency between subjective similarity evaluations and the theoretical predictions derived from Tversky's ratio model of similarity, alongside the impact of additional positive and negative features on perceived similarity to ideal and bad politicians.

Methods

Using a sample of 120 participants, we assessed the similarity of eight candidate profiles to an ideal and bad politician, varying in positive and negative features. Participants' subjective evaluations were compared with theoretical predictions derived from Tversky's ratio model. The analysis focused on how candidate and referent valence influenced observed versus theoretical similarity.

Results

Subjective similarity judgments deviated systematically from theoretical predictions, especially for positively featured candidates, indicating a negativity effect. Additional positive features decreased the perceived similarity of favorable candidates to an ideal politician, while additional negative features did not significantly affect similarity judgments of unfavorable candidates.

Discussion

Our findings underscore a significant disparity between subjective and objective similarity judgments, notably for favorable candidates. While the ratio model performs well for unfavorable candidates, its applicability diminishes for favorable ones, emphasizing the role of feature valence in decision-making. Further research on feature valence is crucial for a comprehensive understanding across contexts.

Positive—Negative Asymmetry in Evaluation of Natural Stimuli: Empirical Study in the Contrast Model of Similarity Extended to Open Sets

The current work shows empirical verification of the similarity theory extended to open sets of features, which states that an increase in similarity between 2 objects results from the deletion of distinctive features or the addition of common features, albeit with different effects. To date, theoretical simulations and empirical demonstrations using real features have shown how the model works. However, to test the validity of the model we conducted an experiment where direct judgments were used. A total of 188 participants were evaluated at 3 different levels related to similarity, affect, and willingness to live, in reference to cities that differed in terms of their amounts of positive and negative features. The results revealed that when their initial similarity to the ideal was greater than 0.5, deletion of distinctive, negative features had a stronger effect on the object evaluation and was more effective than adding positive features of the same value. When the initial similarity to the ideal was less than 0.5, opposite results were obtained; that is, the addition of common, positive features had a stronger effect on the object evaluation than deleting negative features of the same value. The results have shown a positive-negative asymmetry in the evaluation process, which supports the similarity theory extended to open sets of features. In addition, the findings revealed that the positive-negative asymmetry derived from the theory can be explained by the ratio difference principle.