TABLE 3.

Results of the post-study interviews.

Patient	Beliefs regarding the mechanisms of neurofeedback	A priori expectations about the efficacy of neurofeedback	Behavior during the session and beliefs about one’s own role in the neurofeedback
T1 responder	Did not reflect about the principles of neurofeedback.	Was interested to see how neurofeedback would work; expected to see positive results.	Experienced strong relaxation; had to think intensively in order not to fall asleep.
T3 non-responder	Thought that the neurofeedback imagery induced relaxation, may be like hypnosis.	Hoped very much that the method would help, since she had strong pain and nothing helped.	Tried to find how the image was related to her inner feelings; was unable to find anything but believed that the rocket depended on her state.
T4 non-responder	Thought that the speed of the rocket was linked to some physiological processes in her body.	At the beginning of the study, had a strong belief that the neurofeedback would help. In the middle of the study, had doubts about the efficacy of the method and experienced low motivation to come to the trainings [sham phase first]. At the end of the study, the doubts disappeared.	Tried to find how she can influence the neurofeedback game but failed. At the beginning of the study, tried to concentrate on the training, but instead got into a relaxed state. Afterward, just relaxed.
T5 responder	Reported that she understood the mechanisms of neurofeedback after reading the informed consent: the electrodes recorded information about brain wave frequencies, and the speed of the image was influenced by the frequency of the brain.	Before the study, already heard about different biofeedback methods, and was skeptical regarding the potential of neurofeedback to influence headache. Reported that afterward, she had to accept the opposite, since she noticed improvements in headache during and after the study.	Thought that she could influence the speed of the rocket and tried to make experiments. When the rocket was flying too fast, felt drowsiness and tried to slow the rocket down by moving the gaze away (following the rocket with side view), which she believed made the speed more comfortable.
T6 responder	Electrodes registered information about the brain waves, and the image was changing in accordance with brain waves. “I looked at this image and by a cycled mechanism the processes in neural chains influenced what I saw.”	Had a strong hope that neurofeedback would help (because authoritative people told her about this method), but at the same time was skeptical (“could not imagine that it would help”). After the second training, noticed improvement in headache and gained a strong belief that neurofeedback is helpful [neurofeedback phase first]. Closer to the end of the study, was unsure if neurofeedback could help her (experienced stress related to the pandemic and an increase in headache frequency).	Had no feeling that she could consciously influence something. Decided that the speed of the rocket was influenced by her state: when she was active, the rocket was faster; when she was tired, it was slower.
T7 responder	Thought that the speed of the rocket was influenced by the blood flow in her head (when her artery was squeezed, the rocket was moving more erratically).	Was ready to believe in anything. Had doubts regarding the potential efficacy, but was open to everything, and had a hope that neurofeedback would help.	During the second but not the first phase of the treatment, noticed that when she moved the head, the screen got dark [sham first]. Tried to speed up the rocket with her thoughts, reported it did not work.
T8 responder	Thought that the neurofeedback influences her breath, making it more relaxed and leading to general relaxation.	Before the study, thought that the neurofeedback would help her. Closer to the end of the study, had an emotional breakdown caused by an external situation – at this point, she lost her hope in the method.	Thought that she influenced the speed of the rocket, although was not understanding how it was achieved.