Risk perceptions of people living with HIV/AIDS: how similarity affects optimistic bias.

Little as known about how people living with HIV/AIDS (PLWH/A) assess their vulnerability to non-HIV related risk factors, and how this judgement is affected by perceived similarity with others. This study indicates not only that PLWH/A are optimistically biased in their risk pereceptions, but also that they do not use others' HIV status to assess similarity. Perceived similarity with others, however, affects risk judgements: greater the perceived similarity with others, greater the tendency to judge others' vulnerability relative to one's own. Findings point to the importance of considering similarity as a key variable in understanding how risk assessments are made by persons with chronic health conditions.