Since public prejudice and discrimination against person with mental illness could limit their social experiences and opportunities, it is important to give efforts for overcoming public's prejudice and discrimination. Recently NAMI or WPA is applying scientific education method to the public based on attribution theory in order to decrease the prejudice and discrimination. in this context, if the public perceive that a cause of mental illness is uncontrollable due to its biological nature, they show helping behavior with sympathy rather criticize on person with mental illness. Meanwhile, there is a limited study on whether this approach brings reducing public's prejudice and discrimination against mental illness.

This study aims to analyze the influences of causal attribution, controllable causes or uncontrollable causes, on prejudice and discrimination with using vignettes.

The research conducted with 159 respondents who are currently university students and provided them the case vignettes that include typical alcoholism, mood disorder, schizophrenia (acute and chronic case), anti-social personality disorder, based on DSM-IV.

In general the respondents preferred to bad character rather than biological causes in all types of mental illness. in terms of prejudice and discrimination, however, result showed that biological cause more negatively influences on prejudice and discrimination than bad character. Thus, peoples’ perception of cause of mental illness as uncontrollable biological nature makes more prejudice and discrimination.

The results of this study can provide contradiction on theory of cause attribution that argues public's helping behavior with sympathy on individual's uncontrollable cause of mental illness.