Participants of this group received an IBSR intervention workshop.

Participants of this group did not take a part in the workshop.

The IBSR intervention workshop included weekly group meetings (3.5 hours/meeting) for 12 weeks. During the workshop, participants were encouraged to identify and inquire their stressful thoughts. Using self-inquiry practices participants were taught to increase awareness of their thoughts and feelings, to observe their emotional and physical responses during situations perceived by them as stressful, and allow their mind to return to its true, peaceful, creative nature. Through the process of self-inquiry, participants took an active role in investigating their stressful thoughts, and by this regulated their stress and managed symptoms and emotions, thus enabled them to cope better with the psycho-social consequences of the stuttering.

The purpose of OASES-A questionnaire is to assess the overall stuttering experience of adults who stutter. It quantifies the quality of life, satisfaction and overall personal experience of the adult in his daily coping with stuttering. The items in the questionnaire are divided into four main sections: 1. General information on stuttering awareness and perception. 2. Reactions to stuttering. 3. Communication in daily situations. 4. Quality of life.

The OASES-A total score is obtained by summing the scores of the four different sections. In this trial we used the Hebrew version of this questionnaire. OASES-A total score and the score for each of the sections (in the Hebrew version) is ranging from 1.0 to 5.0. The score rates the severity of the stuttering experience, where 1.0 indicates a mild impact rating and 5.0 a severe impact rating (higher scores indicate a more negative impact of stuttering) (Freud et al., 2017; Yaruss & Quesal, 2006).

The STAI questionnaire assess the tendency of adults to experience anxiety and to inspect their sensitivity to anxiety-provoking situations. The questionnaire distinguishes between two scales of anxiety: anxiety as a state and anxiety as a trait. State anxiety is a person's tendency to experience anxiety in certain situations and times, depending on their context. Trait anxiety is a person's constant and stable tendency to experience anxiety frequently.

Each item is rated on a 4-point Likert scale. After completing the questionnaire, items scores are added to obtain total scores. Responders receives 2 separate total scores, one for each of the scales. The maximum score for each scale is 80 and the minimum score is 20. In both scales, scores between 20 to 40 is considered normal in the general adult population. The higher the score, the higher the anxiety level (Spielberger et al., 1970; Taychman & Malinek, 1984).