This study examines cognitive impairment, which is one of the results from social exclusion and leads to logical reasoning disorders. This study also investigate how cognitive errors called abductive inference error occur due to cognitive impairment. Present study was performed with 81 college students. Participants were randomly assigned to the group who has experienced social exclusion or to the group who has not experience the social exclusion. We analyzed how the degree of error of abductive inference differs according to the social exclusion experience. The group who has experienced social exclusion showed a higher level of abductive inference error than the group who has not experience. The abductive condition inference value of the group who has experienced social exclusion was higher in the group with the deduction condition inference value of 90% than in the group with the deduction condition inference value of 10%, and the difference was also significant. This study extended the concepts of cognitive impairments, escape theory, cognitive narrowing which are used to explain addiction behavior to human cognitive bias. Also this study confirmed that social exclusion experience increased cognitive impairment and abductive inference error. Future research directions and implications were discussed and suggested.

Unlike previous studies of overconfidence bias that have been looking for causes of overconfidence bias in human cognitive error or in the desire to view oneself positively, this study presents the cognitive narrowing resulting from the social exclusion experience as the condition of overconfidence bias. It seeks to examine what are the characteristics of cognitive narrowing, which is one of the strategies for overcoming the negative emotions resulting from social exclusion, and how cognitive errors called overconfidence bias occur due to cognitive narrowing. The present study was performed with 94 college students in Seoul. Participants were randomly assigned to a group who experienced social exclusion and a group who did not experience social exclusion. We analyzed how the degree of bias of overconfidence differs according to the experience of social exclusion by t-test. The degree of overconfidence bias of the group who experienced social exclusion was higher than that of the group who did not experience social exclusion, and the difference was statistically significant. This study extends the concepts of escaping theory and cognitive narrowing to human cognitive bias and confirmed that social exclusion experience increased cognitive narrowing and overconfidence bias. Implications and future research directions were discussed.