Acceptance and Commitment Therapy on Psychological Flexibility, Values, and Well-Being: A Single-Case Experimental Study (ACT-UNIVALLE)

Acceptance and Commitment Therapy on Psychological Flexibility, Values, and Well-Being

The goal of this clinical trial is to evaluate the effects of a brief Acceptance and Commitment Therapy (ACT)-based group intervention on psychological flexibility, values-based functioning, and psychological well-being in university students aged 18 to 28 years presenting elevated levels of emotional distress and psychological risk indicators.

The main questions it aims to answer are:

Does a brief ACT-based intervention reduce experiential avoidance and cognitive fusion in university students? Does the intervention improve present-moment awareness, values-based functioning, life satisfaction, and psychological flourishing?

Participants will:

Complete repeated self-report assessments across 13 measurement points distributed throughout baseline, intervention, and follow-up phases.

Participate in five weekly ACT-based group intervention sessions delivered by trained clinical psychologists.

Engage in experiential ACT exercises focused on acceptance, mindfulness, cognitive defusion, values clarification, and committed action.

Complete between-session activities and behavioral practices related to the ACT processes addressed during the intervention.

Participate in follow-up assessments to evaluate maintenance of treatment effects over time.

Study Overview

• Status: Completed
• Conditions: Emotional Distress; Psychological Flexibility; Psychological Well-Being; Experiential Avoidance; Cognitive Fusion
• Intervention / Treatment: Behavioral: Acceptance and Commitment Therapy (ACT)-Based Brief Group Intervention

Detailed Description

University students frequently experience elevated levels of emotional distress, including symptoms of anxiety, depression, stress, worry, and psychological maladjustment. Brief interventions based on Acceptance and Commitment Therapy (ACT) have shown promising results in reducing experiential avoidance and cognitive fusion while promoting psychological flexibility and well-being.

The present study evaluates the effects of a brief ACT-based intervention protocol delivered in a group format using a Single-Case Experimental Design (SCED) with repeated measurements across baseline, intervention, and follow-up phases. The intervention focuses on core ACT processes, including acceptance, cognitive defusion, present-moment awareness, values clarification, and committed action.

Participants completed repeated assessments of psychological flexibility processes and well-being indicators across thirteen measurement points distributed throughout the study phases. The investigators hypothesize that the ACT-based intervention will produce reductions in experiential avoidance and cognitive fusion, together with improvements in present-moment awareness, values-based functioning, life satisfaction, and flourishing.

• Study Type: Interventional
• Enrollment (Actual): 12
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Colombia
  • Valle del Cauca Department
    • Cali, Valle del Cauca Department, Colombia, 760032
      • Faculty of Psychology, Universidad del Valle

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

University students aged 18 years or older Interest in strengthening mental health and psychological well-being Voluntary agreement to participate in the study

High-risk scores on at least one of the following screening instruments:

Depression Anxiety Stress Scales (DASS-21) General Health Questionnaire (GHQ-12) State Worry Questionnaire-11 (SWQ-11)

Exclusion Criteria:

Current psychological or psychiatric treatment Current use of psychiatric medication Diagnosis related to developmental or learning difficulties Failure to attend intervention sessions Incomplete participation in study assessments

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: ACT-Based Brief Group Intervention; The intervention consisted of a brief ACT-based group protocol delivered weekly by trained clinical psychologists. The protocol targeted core ACT processes including acceptance, cognitive defusion, present-moment awareness, values clarification, and committed action. Sessions incorporated experiential exercises, metaphors, mindfulness practices, reflective activities, and between-session behavioral tasks designed to promote psychological flexibility and psychological well-being in university students.

Behavioral: Acceptance and Commitment Therapy (ACT)-Based Brief Group Intervention; The intervention consisted of a brief group-based Acceptance and Commitment Therapy (ACT) protocol designed to promote psychological flexibility and psychological well-being in university students presenting elevated emotional distress and psychological risk indicators. The protocol was grounded in the functional contextual approach and targeted core ACT processes, including acceptance, cognitive defusion, present-moment awareness, values clarification, and committed action. Participants were organized into small groups of 5 to 8 individuals and attended five weekly intervention sessions conducted by trained clinical psychologists with at least five years of clinical experience. Prior to implementation, therapists completed specialized ACT training delivered by an expert clinician with extensive experience in Acceptance and Commitment Therapy. The intervention protocol included an initial preliminary session focused on motivational engagement, informed consent procedures, feedback rega; Other Names: ACT Brief; ACT Protocol Group; ACT Intervention

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mindful Attention Awareness Scale (MAAS)	The Mindful Attention Awareness Scale (MAAS) is a 15-item self-report questionnaire designed to assess present-moment attention and awareness in daily life. Items are rated on a 6-point Likert-type scale ranging from 1 ("almost always") to 6 ("almost never"). Total scores are calculated by summing item responses, with higher scores indicating greater mindfulness and present-moment awareness.	Weekly during baseline (4 weeks), intervention (6 weeks), and follow-up (3 weeks), up to 13 weeks
Acceptance and Action Questionnaire-II (AAQ-II)	The Acceptance and Action Questionnaire-II (AAQ-II) is a 7-item self-report questionnaire designed to assess experiential avoidance and psychological inflexibility. Items are rated on a 7-point Likert-type scale ranging from 1 ("never true") to 7 ("always true"). Total scores are calculated by summing item responses, with higher scores indicating greater experiential avoidance and psychological inflexibility.	Weekly during baseline (4 weeks), intervention (6 weeks), and follow-up (3 weeks), up to 13 weeks.
Cognitive Fusion Questionnaire (CFQ)	The Cognitive Fusion Questionnaire (CFQ) is a 7-item self-report questionnaire designed to assess cognitive fusion. Items are rated on a 7-point Likert-type scale ranging from 1 ("never true") to 7 ("always true"). Total scores are calculated by summing item responses, with higher scores indicating greater cognitive fusion.	Weekly during baseline (4 weeks), intervention (6 weeks), and follow-up (3 weeks), up to 13 weeks.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Valuing Questionnaire - Obstruction Subscale (VQ-Obstruction)	The Valuing Questionnaire - Obstruction Subscale (VQ-Obstruction) is a 5-item self-report measure designed to assess barriers and interference with values-based living. Items are rated on a 7-point Likert-type scale ranging from 0 ("not at all true") to 6 ("completely true"). Higher scores indicate greater obstruction in valued living.	Weekly during baseline (4 weeks), intervention (6 weeks), and follow-up (3 weeks), up to 13 weeks.
Satisfaction With Life Scale (SWLS)	The Satisfaction With Life Scale (SWLS) is a 5-item self-report questionnaire designed to assess global life satisfaction. Items are rated on a 7-point Likert-type scale ranging from 1 ("strongly disagree") to 7 ("strongly agree"). Total scores are calculated by summing item responses, with higher scores indicating greater life satisfaction.	Weekly during baseline (4 weeks), intervention (6 weeks), and follow-up (3 weeks), up to 13 weeks.
Flourishing Scale (FS)	The Flourishing Scale (FS) is an 8-item self-report questionnaire designed to assess psychological flourishing, including meaning in life, interpersonal relationships, competence, and optimism. Items are rated on a 7-point Likert-type scale ranging from 1 ("strongly disagree") to 7 ("strongly agree"). Total scores are calculated by summing item responses, with higher scores indicating greater psychological flourishing.	Weekly during baseline (4 weeks), intervention (6 weeks), and follow-up (3 weeks), up to 13 weeks.

Collaborators and Investigators

• Sponsor: Universidad del Valle, Colombia

Study record dates

Study Major Dates

• Study Start (Actual): April 1, 2025
• Primary Completion (Actual): June 15, 2025
• Study Completion (Actual): June 30, 2025

Study Registration Dates

• First Submitted: May 12, 2026
• First Submitted That Met QC Criteria: May 26, 2026
• First Posted (Actual): June 2, 2026

Study Record Updates

• Last Update Posted (Actual): June 2, 2026
• Last Update Submitted That Met QC Criteria: May 26, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Acceptance and Commitment Therapy; Mental Health; Psychological Flexibility; Brief Psychological Intervention; Single-Case Experimental Design
• Additional Relevant MeSH Terms: Behavior; Personal Satisfaction; Psychological Well-Being
• Other Study ID Numbers: Universidad del Valle; UNIVALLE-ACT-2025 (Other Identifier: Faculty of Psychology, Universidad del Valle); Faculty of Psychology (Other Identifier: Faculty of Psychology, Universidad del Valle)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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