This study examined the relationship between the amount of legal knowledge, knowl-
edge of the lay judge system, cognitive factors (i.e., perceived risk to one’s life, perceived
cost to act as a saiban-in “lay judge,” perceived benefit to act as a saiban-in), emotions
(anxiety, stress, and anticipated regret), and behaviors (i.e., intentions and requests to
act as a saiban-in) in the lay judge system. First, we surveyed a sample of 307 citizens
in 2007 and 700 citizens in 2012, and compared the decision-making processes in these
two years using structural equation modeling. The results indicated that the effect of
perceived benefit to act as a saiban-in on intentions was weaker in 2012 than 2007.
In contrast, the effect of perceived cost was stronger in 2012 than in 2007. This may
explain why the intention to act as a saiban-in was low in 2012, despite the greater
knowledge of saiban-in processes in 2012 than in 2007. Second, the groups in 2012 were
(1) males with a decision-making style defined by low responsibility scores, (2) males
with high responsibility scores, (3) females with low scores, and (4) females with high
scores. We examined the decision-making processes among the groups. For all groups,
there was a cognitive process that perceived risk to one’s life affected intentions to act
as a saiban-in, mediated by the perceived cost to act as a saiban-in. However, emo-
tional process differed among groups. Therefore, in order to increase intentions to act
a saiban-in, it is necessary to provide information that draws on individual differences
(e.g., gender, decision-making style), particularly including emotional content.
