title: Impact of short-term meditation and expectation on executive brain functions.
abstract: Meditation improves executive functions such as attention and working memory processes. However, it remains unclear to what extent contextual effects contribute to these improvements, since the role of meditation-associated expectations has not been investigated so far. In a randomized, single-blind, deceptive, between-subject design we compared the impact of short-term meditation (MG) on executive functioning with an expectation (ECG) and a passive control group (CG) as well as the effect of positive and negative outcome expectations. Fifty-nine healthy meditation-naïve volunteers participated on three consecutive days (20 min/session). Five groups were examined: 2 MGs, 2 ECGs and 1 CG. While one MG and one ECG were given positive suggestions concerning the effect of meditation on attention, the other two groups were given negative suggestions. MGs practised a focused attention meditation technique; ECGs were told that they were practising meditation but were given instructions for a sham meditation. CG participants sat in silence with their eyes closed. Interference control (Stroop task), selective sustained attention (d2 task), figural and verbal fluency measures of executive functions were assessed. Results indicate that suggestions have a substantial impact on interference control and verbal fluency, with positive suggestions leading to an increase in performance, whereas negative suggestions impeded improvement. This proof of concept study demonstrates the importance of the implementation of a credible ECG to elucidate context effects in meditation processes. It also indicates that suggestions can modulate the small effect of meditation on verbal fluency.
authors.affiliation: Division of Clinical Psychology and Psychotherapy, Department of Psychology, University of Basel, Missionsstrasse 60/62, 4055 Basel, Switzerland; Department of Child and Adolescent Psychiatry, Psychiatric University Clinics, Schanzenstrasse 13, 4056 Basel, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Prätzlich
authors.affiliation: Division of Clinical Psychology and Psychotherapy, Department of Psychology, University of Basel, Missionsstrasse 60/62, 4055 Basel, Switzerland; Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Harvard Medical School, Boston, USA.
authors.forename: Joe
authors.initials: J
authors.lastname: Kossowsky
authors.affiliation: Division of Clinical Psychology and Psychotherapy, Department of Psychology, University of Basel, Missionsstrasse 60/62, 4055 Basel, Switzerland.
authors.forename: Jens
authors.initials: J
authors.lastname: Gaab
authors.affiliation: Division of Clinical Psychology and Psychotherapy, Department of Psychology, University of Basel, Missionsstrasse 60/62, 4055 Basel, Switzerland; Collegium Helveticum, Schmelzbergstrasse 25, CH-8092 Zurich, Switzerland; Brainability LLC, CH-8057 Zurich, Switzerland. Electronic address: krummenacher@collegium.ethz.ch.
authors.forename: Peter
authors.initials: P
authors.lastname: Krummenacher
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D059031:Anticipation, Psychological; D001288:Attention; D056344:Executive Function; D005260:Female; D006801:Humans; D008297:Male; D019122:Meditation; D008875:Middle Aged; D064866:Mindfulness; D016037:Single-Blind Method; D057190:Stroop Test; D055815:Young Adult
keywords: Attention; Executive functions; Expectation; Meditation; Placebo; Stroop; Suggestion