Introduction: In group learning settings like problem-based learning (PBL), the quality of interaction is closely related to group success. However, research and practice have shown that the interaction in tutorial groups is not optimal. In the present study, a questionnaire was used to measure students' perceptions of occurrence and desirability of three interaction types, i.e. exploratory questioning, cumulative reasoning, and handling knowledge conflicts. The discrepancies between the perceptions of occurrence and desirability enabled us to illustrate how the questionnaire can be used to improve the group interaction process in the tutorial group. Method: The subjects consisted of all second-year medical students of Maastricht University (N=240, response rate 73%). The questionnaire consisted of a list of eleven statements representing the three interaction types (factors). Students were asked to rate each statement on a 5-point Likert scale for two types of perceptions, i.e. occurrence and desirability. Results: The average scores on occurrence and desirability of the interaction types varied between 3.4 and 3.7 (scale 1-5) and between 3.6 and 4.3, respectively. For two interaction types, significant differences between occurrence and desirability were found. Conclusion: The scores for occurrence were reasonable, and the desirability scores were significantly higher than the occurrence scores for two of the three interaction types, i.e., exploratory questioning and cumulative reasoning. The results of the present study imply that in the students' opinion, the interaction process in the tutorial group can be improved. The questionnaire provides useful information to detect shortcomings in the tutorial group interaction.