Investigators compared the tube movement between two situations; the one was that the practitioner's hand holding the tracheal tube was placed in the air, and the other was that the hand was placed on the manikin's cheek, while two residents took the roles of the practitioner and the assistant in tracheal intubation with a stylet for a manikin.

Residents who accepted spontaneous participation were randomly combined into teams of two each. For two residents in a team, each sequentially took on the role of a practitioner and once as an assistant for tracheal intubations by changing the position of the hand holding the tube; one time, the position of the hand holding the tube was placed in the air, and the other time, the position of the hand holding the tube was placed on the cheek of the manikin. For the assistant role, residents performed stylet removal with two hands. Investigators filmed a video of the tube movement while the assistant pulling up the stylet at 1/8x speed. While analyzing the captured videos, it was measured how much the tube held by the intubation practitioner went in front or how far back during the process of pulling the stylet.

Inclusion Criteria:

• residents in the department of Anesthesia and Pain Medicine

Exclusion Criteria:

• refusal for participation

Residents in the department of Anesthesia and Pain Medicine