Studies have shown that observers are able to accurately assess a partner’s confidence in his decision without sharing verbal information. The main question of this study is whether an adequate assessment of the metacognitive experiences of others is possible if they make decisions based on implicit knowledge. The experiment was conducted according to the method of artificial grammar. The results of the study demonstrate that the assessment of self-confidence by participants who classify stimuli of artificial grammar correlates with the confidence scores of their partners’ who observe the classification process but are not participating in it and who do not have access to the stimuli. The self-confidence of the learners correlates with the correctness of their answers. It is concluded that in assessing the confidence of others and assessing their own confidence, participants are partially guided by similar criteria, but only self-assessments of confidence in the decision process is sensitive to the presence of implicit knowledge.