The purpose of the current study was to determine the impact of different forms of feedback (text/image/video) on the transactional distance (TD) perceptions and critical thinking skills (CTS) of the learners in online collaborative discussions. The study was designed as a quasi-experimental study and was carried out with the participation of 104 pre-service teachers. TD Scale and Critical Thinking Standards Scale were used as data collection instruments. The findings revealed that whilst the form of feedback had a significant difference on TD perception, it did not create a significant difference on CTS. When the impact of feedback form on TD perception of the learners was examined, it was seen that the group with the lowest TD perception was the one which was given video-based feedback in online discussions. This group was followed by the groups to whom image- and text-based feedback was given.