This study explores the distribution of back-channel feedback in terms of modality in a doctor-patient interaction. The literature studied revealed that previous studies on feedback hardly considered hand gestures among the modalities that serve this function. In this study we therefore investigate whether hand gestures can perform a feedback function or not. Preliminary results show that back-channel feedback is mostly expressed through two modalities: speech and head movements, separated or together. However, we also observe some hand gesture feedback. Interestingly, we find that adaptors can be used as feedback when produced for a communicative purpose.