The desirability bias in personality-related syllogistic reasoning.

Introduction: The belief-bias effect is a tendency to evaluate syllogistic statements based on believability rather than on formal logic validity. Following this rationale, the study examines desirability bias as the tendency to evaluate syllogistic conclusions based on their desirability when reasoning is conducted on personality-relevant categorical syllogisms.

Methods: For this purpose, 60 syllogisms were constructed based on the items of the Big Five questionnaire. Syllogisms were subsequently categorized as desirable (e.g., "I empathize with others") and undesirable (e.g., "I am passive") based on their conclusion. In each task, the second premise and the conclusion were formulated in the first person to increase a respondent's identification with the content. A total of 300 university students (M_age = 20.08, SD = 2.02) participated in the study.

Results: A 2 (syllogism validity: valid, invalid) × 2 (syllogism desirability: desirable, undesirable) repeated measures ANOVA was employed. The analysis showed a greater tendency to accept desirable conclusions on valid syllogisms (valid desirable rather than valid undesirable) and reject undesirable conclusions on invalid syllogisms (invalid undesirable rather than invalid desirable).

Conclusion: These findings have implications for socially desirable responding in cognitive tasks, which may be further developed as a source of self-relevant content as well as for further extension of belief bias in the form of desirability bias.