Objectives: In clinical reasoning, clinicians need to switch between automatic and effortful reasoning to solve both routine and non-routine problems. This requires the ability to recognise when a problem is non-routine and adapt one's reasoning mode accordingly, that is to ‘slow down’ the reasoning process. In the current study, we explored the process of these transitions between automatic and effortful reasoning by radiologists who performed ultrasound examinations during consultations at the polyclinic. Methods: Manifestations of slowing down in clinical reasoning were explored in 41 out-patient consultations performed by five radiologists. Interviews before and after the consultations were combined with observations during the consultations to obtain proactively planned triggers, slowing down manifestations and situationally responsive initiators. Transcripts of the interviews and field notes of the observations were coded. The constant comparative method was used to classify slowing down manifestations. Results: In thirteen of the 41 consultations, slowing down moments were observed. Four manifestations of slowing down were identified: shifting, checking, searching and focusing. These manifestations mainly differed in how long radiologists maintained effortful reasoning, varying from very short periods (shifting and checking) to sustained periods (searching and focusing). Unexpected patient statements and ambiguous ultrasound images initiated the slowing down moments. Discussion: The results from this study contribute to understanding how clinicians transition from automatic to effortful reasoning. Also, this study revealed two sources of initiators of this transition in radiologists’ consultations: statements made by the patient and conflicting or ambiguous visual information, in this case from ultrasound images. Natural variations in patient statements and visual information can be used as input of what might be meaningful variation in the domain of radiology education to support expertise development.