Eight of the students — six men and two women — engaged in flotation sessions for four consecutive weeks. They spent an hour each week in a fiberglass shell, floating in a solution of Epsom salts and skin-temperature water. They were in the dark, and outside sounds were muffled.
All the participants — including the other five musicians who comprise the comparison group — made two five-minute-long recordings in which they freely improvised. The first took place one week before the flotation sessions began; the second, one week after the sessions concluded. Each session was rated by the instructor (who was unaware which students were undergoing the treatments) on five dimensions: improvisation, creativity, expressiveness, technical ability and overall quality.
The researchers found “a significant difference between the treatment and comparison groups on technical ability, but not on any other dimension,” the researchers write. Thanks to this enhanced skill level, those who had floated “had significantly higher grades in the jazz improvisation class than the comparison group.”
Vartanian and Suedfeld concede this was a small sample. But they note that, based on their initial recordings, the instructor rated the treatment and comparison groups essentially equal on all five dimensions. Since “The two groups can be considered equivalent in terms of motivation and baseline ability,” the difference in their ability was very likely the result of the flotation sessions.