Breathing and Decision-Making (ProlEx-Context) (ProlEx-Context)

The ProlEx-Context study aims to investigate how a slow-paced breathing technique with prolonged exhalation affects decision-making in the context of acute social stress.

Study Overview

• Status: Not yet recruiting
• Conditions: Decision-Making; Breathing Techniques; Stress Management
• Intervention / Treatment: Behavioral: Instructed Prolonged Exhalation; Behavioral: Instructed Individualized Eupnea

Detailed Description

The ProlEx-Context study explores how a slow breathing technique with prolonged exhalation can restore decision-making processes after exposure to acute social stress.

Method Overview:

The methods of the study include a guided breathing exercise (prolonged exhalation vs normal breathing rhythm), exposure to acute social stress, peripheral electrophysiology (respiration, pulse, gastric and cardiac rhythms, skin conductance, pupillometry), salivary cortisol sampling, psychological questionnaires, behavioral tasks and functional brain imaging with fMRI.

Participant Overview:

An estimated 50 participants will be invited to this within-subject fMRI study and will be blinded to the stress induction component of this study.

Time frame:

One appointment of approx. 4 hours per person.

Procedure Overview:

Participants will be invited to the testing site at approximately 4 PM. Upon completion of the preparations and placement inside the MRI, the participants will undergo an adapted virtual Trier Social Stress Test (TSST). After completing the TSST, the participants are asked to perform a risk decision-making task inside the MRI, during which they are displayed a visual cue to assist during guided breathing. The participants perform blocks of either normal breathing or prolonged exhalation breathing during performance of the decision-making task in a randomized cross-over-design. During the task, brain activity and peripheral physiological signals, such as the respiration rate, heart rate, skin conductance and pupil dilation are measured. After completion of the first breathing condition (three blocks) and before the second breathing condition, participants will undergo a second TSST. Before and after each TSST, at baseline and after completion of the decision-making task, salivary samples for cortisol assessment are taken. After completion of the decision-making task, participants will be asked to fill out a battery of psychometric questionnaires and reimbursed for their time.

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Soyoung Q Park, Prof. Dr.; Phone Number: +49 033200 88 2510; Email: soyoung.park@dife.de
• Study Contact Backup: Name: Wenhao Huang; Email: Wenhao.Huang@dife.de

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• 18- to 40-year-old men and women
• Consent to participate
• Fluent in German
• Right-handed
• Physically and mentally healthy without regular medication
• Body-mass index of 18-25 kg/m2
• Alcohol consumption of less than 15 glasses a week (equivalent to one glass of wine/beer, a glass of higher-percentage alcohol counts as two glasses of beer)
• No illegal drug consumption in the week previous to the experiment
• No smoking
• No competitive athletes
• Normal day-night rhythm (no shift work)
• Normal vision without required vision correction (i.e., glasses, contact lenses; ability to clearly read texts at a distance of up to 50 cm without vision aids)

Exclusion Criteria:

• Former or current illnesses of:
• Brain or mind (including anxiety disorders, depression, eating disorders, personality disorders, alcohol, drugs or drug dependence, neurological disorders other than occasional headache, psychiatric or neurological abnormalities)
• Heart or blood circulation
• Lung Diseases
• Other serious past or present medical conditions (for example, metabolic syndrome, diabetes)
• Current medication and medication over a period of two weeks prior to the examination
• Other serious health problems or present strong mental or physical stress
• Current infection or excessive stress
• Missing consent to receive information about incidental findings from the MRI
• Tendency to claustrophobia, dizziness, or panic attacks
• Wearing a non-removable pacemaker, defibrillator, hearing aid, drug pump, neurostimulator or implant with solenoid valve (e.g., artificial bowel outlet)
• Metal parts or implants inside the body, for example, due to surgery or injury with a metallic foreign object (e.g., hip replacements, artificial joints, heart valves, vessel occlusions or dilatations, surgical clips, bone screws or plates, coil, shunts, catheters, electrodes, coils, radiation sources, shrapnel, projectiles, stents)
• Having non-removable metal parts or metal-containing devices on or in the body
• Having ferromagnetic metal parts or implants inside the body (e.g., hip replacements, artificial joints, heart valves, vessel occlusions or dilatations, surgical clips, bone screws or plates, coils, shunts, catheters, electrodes, coils, radiation sources, shrapnel, projectiles, stents)
• Wearing magnetically fixed implants (e.g. amalgam fillings, glass eye)
• Professionally or privately being involved in the processing of ferromagnetic metals
• Large tattoos (whole limbs)
• Pregnancy
• Wearing an intra-uterine device
• Having tinnitus
• Extensive lung function (e.g. apnoe diver, singer, professional musician with lung-involving instruments)
• Previous participation in the ProlEx-MRI study (the precursor to the current study)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Prolonged Exhalation Breathing; Participants are required to perform a specific voluntarily controlled breathing pattern directed by visual cues. The core characteristic is a systematic lengthening of the expiratory phase relative to the inspiratory phase. Specifically, participants are instructed to inhale for 2 seconds and prolong their exhalation to 8 seconds	Behavioral: Instructed Prolonged Exhalation; Participants are required to perform a specific instructed breathing pattern directed by visual cues. The core characteristic is a systematic lengthening of the expiratory phase relative to the inspiratory phase. Specifically, participants are instructed to inhale for 2 seconds and prolong their exhalation to 8 seconds.
Experimental: Eupnea Breathing (Normal); Eupnea (Normal breathing) condition: In this control condition, participants maintain their spontaneous respiratory rhythm. The pacing for eupnea is individualized for each participant, based on their natural breathing frequency sampled during representative non-interventional intervals of the session (e.g., baseline or post-stress recovery periods). This ensures the control condition reflects the participant's characteristic physiological state within the experimental context.	Behavioral: Instructed Individualized Eupnea; Instructed Individualized Eupnea: In this control condition, participants are instructed to match their breath to a visual cue that is calibrated to their own characteristic natural respiratory frequency. This frequency is sampled during representative non-interventional phases of the session to capture the participant's individual baseline eupnea pace within the experimental context.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Risk propensity	The dependent variable will be trial-wise gamble acceptance (accept vs. reject of a 50% gamble), which will be mainly analyzed using a binomial generalized linear mixed-effects model (GLMM) to compare the Prolonged Exhalation and Eupnea conditions under acute stress.	On day 1.
Task-related BOLD Signals	Task-related changes in blood-oxygen-level-dependent (BOLD) signals measured using functional magnetic resonance imaging (fMRI).	On day 1.
Structural T1-weighted MRI	High-resolution T1-weighted structural images measured using magnetic resonance imaging (MRI).	On day 1.
Relative amplitude of the respiratory signal	Task-based and resting-state relative respiratory amplitude, measured via a respiratory belt and nasal airflow sensor.	On day 1.
Respiration rate	Task-based and resting-state relative respiratory amplitude, measured via a respiratory belt and nasal airflow sensor.	On day 1.
Heart rate	Task-based and resting-state heart rate, measured with ECG	On day 1.
Heart-rate variability	Task-based and resting-state heart-rate variability, measured with a three-point electrocardiogram (ECG)	On day 1.
Gastric myoelectrical activity	Resting-state and task-based gastric myoelectrical activity, measured using cutaneous electrogastrography (EGG).	On day 1.
Tonic skin conductance	Tonic task-based and resting-state electrodermal activity, measured with EDA electrodes	On day 1.
Event-related skin conductance responses	Phasic electrodermal activity, measured via electrodermal activity (EDA) electrodes	On day 1.
Salivary Cortisol Levels	Concentration of cortisol in saliva (measured in nmol/L). This indexes the HPA-axis response to the Trier Social Stress Test (TSST). We will compare the cortisol trajectory	On day 1.
Pupil dilation	Task-based and resting-state pupil dilation, measured via eye-tracking	On day 1.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Response Times	The average time (in milliseconds) taken by participants to make a choice in each trial.	On day 1.
Self-reported levels of stress	Self-reported levels of stress will be measured via a Visual Analog Scale (VAS) ranging from 0 to 100. A score of 0 represents "not at all" and 100 represents "extremely high."	On day 1.
Self-reported levels of tension	Self-reported levels of tension will be measured via a Visual Analog Scale (VAS) ranging from 0 to 100. A score of 0 represents "not at all" and 100 represents "extremely high."	On day 1.
Self-reported levels of heart feeling	Self-reported levels of heart feeling will be measured via a Visual Analog Scale (VAS) ranging from 0 to 100. A score of 0 represents "not at all" and 100 represents "extremely high."	On day 1.
Self-reported levels of stomach feeling	Self-reported levels of stomach feeling will be measured via a Visual Analog Scale (VAS) ranging from 0 to 100. A score of 0 represents "not at all" and 100 represents "extremely high."	On day 1.
State and Trait Anxiety questionnaires	trait and state anxiety, assessed via the State-Trait Anxiety Inventory (STAI-S and STAI-T). State anxiety is assessed on a scale from "not at all" to "very much" on an 8-point scale, and trait anxiety is assessed on a scale from 0 to 3, with higher scores indicating higher anxiety.	On day 1.
Affect questionnaire	Positive and negative affect, assessed via the Positive and Negative Affect Schedule (PANAS). Responses range from "not at all" to "extremely" on a 5-point scale (from 0 to 5). Higher positive affect scores indicate greater positive affect, and higher negative affect scores indicate greater negative affect.	On day 1.
Depression questionnaire	Depressive symptoms, assessed via the Beck Depression Inventory (BDI). Items are rated from 0 to 3 based on how the participant felt during the past week including today, with higher scores indicating greater depressive symptoms.	On day 1.
Personality questionnaire	Personality traits, assessed via the Big Five Inventory (BFI-10). Responses range from "strongly disagree" to "strongly agree" on a 5-point scale (from 1 to 5). Higher subscale scores indicate greater levels of the corresponding personality trait.	On day 1.
Impulsivity questionnaire	Impulsivity, assessed via the Barratt Impulsivity Scale (BIS-15). Items are rated on a scale from 1 to 4, with higher scores indicating greater impulsivity.	On day 1.
Self-control questionnaire	Self-control, assessed via the Brief Self-Control Scale (BSCS). Responses range from "not at all" to "very much" on a 5-point scale (from 0 to 5), with higher scores indicating greater self-control.	On day 1.
Behavioral inhibition and activation questionnaire	Behavioral inhibition and activation, assessed via the BIS/BAS scales. Items are rated on a scale from 1 to 4, with higher scores indicating stronger inhibition or activation tendencies.	On day 1.
Interoceptive awareness questionnaire	Interoceptive awareness, assessed via the Multidimensional Assessment of Interoceptive Awareness (MAIA). Responses range from "never" to "always" on a 6-point scale (from 0 to 5). Higher subscale scores indicate greater self-reported interoceptive awareness in the corresponding domain.	On day 1
Perceived stress questionnaire	Perceived stress, assessed via the Perceived Stress Questionnaire (PSQ). Responses range from "almost never" to "usually" on a 4-point scale (from 0 to 5), referring to the past 4 weeks, with higher scores indicating greater perceived stress.	On day 1.
Self-efficacy questionnaire	General self-efficacy, assessed via the Self-Efficacy Scale (SES). Responses range from "not at all true" to "exactly true" on a 4-point scale (from 1 to 4), with higher scores indicating greater self-efficacy.	On day 1
Mental well-being questionnaire	Mental well-being, assessed via the Warwick-Edinburgh Mental Well-Being Scale (WEMWBS). Responses range from "never" to "always" on a 5-point scale (from 1 to 5), with higher scores indicating greater mental well-being over the past 2 weeks.	On day 1.
Loneliness questionnaire	Loneliness, assessed via the UCLA Loneliness Scale. Responses range from "not at all" to "completely" on a 5-point scale (from 1 to 5), with higher scores indicating greater loneliness.	On day 1
Resilience questionnaire	Resilience, assessed via the Brief Resilience Scale (BRS). Responses range from "strongly disagree" to "strongly agree" on a 5-point scale (from 0 to 5), with higher scores indicating greater resilience.	On day 1.
Social anxiety questionnaire	Social anxiety, assessed via the Liebowitz Social Anxiety Scale (LSAS). Fear and avoidance are each rated on a scale from 0 to 3, with higher scores indicating greater social anxiety.	On day 1.
Autism traits questionnaire	Autism-related traits, assessed via the Autism-Spectrum Quotient (AQ-k). Items are rated on a 4-point scale (from 1 to 4), with higher scores indicating greater endorsement of autism-related traits.	On day 1.
Physical activity questionnaire	Physical activity, assessed via the International Physical Activity Questionnaire - Short Form (IPAQ-SF). The questionnaire assesses the number of days and time spent in vigorous activity, moderate activity, walking, and sitting over the past 7 days, considering activities performed for at least 10 minutes without interruption. Higher values indicate greater reported activity or sedentary time in the respective domain.	On day 1.
Sleep quality questionnaire	leep quality, assessed via the Pittsburgh Sleep Quality Index (PSQI). The questionnaire assesses sleep habits over the past 4 weeks, including sleep timing, duration, disturbances, and subjective sleep quality. Several items are rated on 4-point scales, with higher scores indicating poorer sleep quality.	On day 1.

Collaborators and Investigators

• Sponsor: German Institute of Human Nutrition
• Investigators: Principal Investigator: Soyoung Q Park, Prof. Dr., German Institute of Human Nutrition Potsdam-Rehbruecke

Publications and helpful links

General Publications

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• Mehling WE, Acree M, Stewart A, Silas J, Jones A. The Multidimensional Assessment of Interoceptive Awareness, Version 2 (MAIA-2). PLoS One. 2018 Dec 4;13(12):e0208034. doi: 10.1371/journal.pone.0208034. eCollection 2018.
• Backhaus J, Junghanns K, Broocks A, Riemann D, Hohagen F. Test-retest reliability and validity of the Pittsburgh Sleep Quality Index in primary insomnia. J Psychosom Res. 2002 Sep;53(3):737-40. doi: 10.1016/s0022-3999(02)00330-6.
• Chmitorz A, Wenzel M, Stieglitz RD, Kunzler A, Bagusat C, Helmreich I, Gerlicher A, Kampa M, Kubiak T, Kalisch R, Lieb K, Tuscher O. Population-based validation of a German version of the Brief Resilience Scale. PLoS One. 2018 Feb 13;13(2):e0192761. doi: 10.1371/journal.pone.0192761. eCollection 2018.
• Heimberg RG, Horner KJ, Juster HR, Safren SA, Brown EJ, Schneier FR, Liebowitz MR. Psychometric properties of the Liebowitz Social Anxiety Scale. Psychol Med. 1999 Jan;29(1):199-212. doi: 10.1017/s0033291798007879.
• Allen AP, Kennedy PJ, Dockray S, Cryan JF, Dinan TG, Clarke G. The Trier Social Stress Test: Principles and practice. Neurobiol Stress. 2016 Nov 12;6:113-126. doi: 10.1016/j.ynstr.2016.11.001. eCollection 2017 Feb.
• Tom SM, Fox CR, Trepel C, Poldrack RA. The neural basis of loss aversion in decision-making under risk. Science. 2007 Jan 26;315(5811):515-8. doi: 10.1126/science.1134239.
• Grimm, J. State-trait-anxiety inventory nach Spielberger. Deutsche Lang- und Kurzversion. Methodenforum der Universität Wien: MF-Working Paper (2009).
• Meule, A., Vögele, C. & Kübler, A. Psychometrische Evaluation der deutschen Barratt Impulsiveness Scale - Kurzversion (BIS-15). Diagnostica 57, 126-133 (2011).
• Schwarzer, R., Bäßler, J., Kwiatek, P., Schröder, K., & Zhang, J. X. (1997). The assessment of optimistic self-beliefs: comparison of the German, Spanish, and Chinese versions of the general self-efficacy scale. Applied Psychology, 46(1), 69-88.
• Freitag, C. M., Retz-Junginger, P., Retz, W., Seitz, C., Palmason, H., Meyer, J., ... & von Gontard, A. (2007). Evaluation der deutschen version des Autismus-Spektrum-Quotienten (AQ)-die Kurzversion AQ-k. Zeitschrift für klinische Psychologie und Psychotherapie, 36(4), 280-289.
• Döring, N., & Bortz, J. (1993). Psychometrische Einsamkeitsforschung: Deutsche Neukonstruktion der UCLA Loneliness Scale. Zeitschrift für Klinische Psychologie, 22(3), 224-233.
• Lang, G. & Bachinger, A. Validation of the German Warwick-Edinburgh Mental Well-Being Scale (WEMWBS) in a community-based sample of adults in Austria: a bi-factor modelling approach. J Public Health 25, 135-146 (2017).
• Fliege, H., Rose, M., Arck, P., Levenstein, S. & Klapp, B. F. (2001). Validierung des "Perceived Stress Questionnaire" (PSQ) an einer deutschen Stichprobe. Diagnostica, 47, 142-152.
• Janke, S., & Glöckner-Rist, A. (2014). "Deutsche Version der Positive and Negative Affect Schedule (PANAS)" in Zusammenstellung sozialwissenschaftlicher Items und Skalen, GESIS (Mannheim, Germany).
• Strobel, A., Beauducel, A., Debener, S., & Brocke, B. Eine deutschsprachige Version des BIS/BAS-Fragebogens von Carver und White. [A German version of Carver and White's BIS/BAS scales.]. Zeitschrift für Differentielle und Diagnostische Psychologie 22, 216-227 (2001).
• Rammstedt, B., Kemper, C.J., Klein, M.C., Beierlein, C., & Kovaleva, A. (2013). Eine kurze Skala zur Mes-sung der fünf Dimensionen der Persönlichkeit. Methoden, Daten, Analysen, 7(2), S. 233-249.
• Hautzinger, M., Bailer, M., Worall, H. and Keller, F. (1994). Das Beck Depressionsinventar (BDI) [The Beck Depression Inventory (BDI)]. Bern: Huber.
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• Bae D, Matthews JJL, Chen JJ, Mah L. Increased exhalation to inhalation ratio during breathing enhances high-frequency heart rate variability in healthy adults. Psychophysiology. 2021 Nov;58(11):e13905. doi: 10.1111/psyp.13905. Epub 2021 Jul 20.

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): April 1, 2027
• Study Completion (Estimated): April 1, 2027

Study Registration Dates

• First Submitted: March 13, 2026
• First Submitted That Met QC Criteria: March 26, 2026
• First Posted (Actual): April 1, 2026

Study Record Updates

• Last Update Posted (Actual): April 1, 2026
• Last Update Submitted That Met QC Criteria: March 26, 2026
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Other Study ID Numbers: ProlEx-Context; 88/2025 107/2025 (Other Identifier: Ethics Committee of the University of Potsdam)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

IPD Plan Description

A decision regarding sharing of individual participant data (IPD) has not yet been made.

The dataset includes behavioral, physiological, and neuroimaging data, and any future data sharing will be subject to institutional policies and applicable data protection regulations.

Data sharing options will be evaluated following study completion.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No