Participation dashboards in online discussions are learning support tools that can have a positive effect on learners' learning outcomes and satisfaction levels, but their effectiveness differs according to how learners recognize and interpret them. However, there is a lack of research investigating the effectiveness of visualization methods regarding learners' participation levels. Accordingly, in this study, two visualization methods are applied to participation dashboards to show peer participation levels and to support online discussion activities. The Transparent Participation Dashboard (TPD) provides the exact participation levels for all learners who participate in an online discussion, whereas the Private Participation Dashboard (PPD) visualizes a learner's relative level of participation in comparison to the average value of a class. This study aimed to compare the effects of these two types of participation dashboards on the behavioral, cognitive, and affective aspects of online discussion activities. Toward this end, we conducted an experimental study. The participants included 62 undergraduate students who were randomly assigned to two groups. Thirty-two students were assigned to the Transparent group, which received the TPD. Thirty students were assigned to the Private group, which received the PPD. Our findings showed no significant difference in usability, quality of discussions, or learning outcomes between the two groups. However, the Transparent group was more active in its online discussions and expressed more negative satisfaction with the dashboard. This study's conclusions suggest that dashboards for promoting learner competitiveness can positively affect learners' behavioral aspects but they may negatively impact their emotions.