Effect of a One-Session ACT Protocol in Disrupting Repetitive Negative Thinking: A Randomized Multiple-Baseline Design

Complete Reference

Ruiz, F. J., Riaño-Hernández, D., Suárez-Falcón, J. C., & Luciano, C. (2016). Effect of a one-session ACT protocol in disrupting repetitive negative thinking: A randomized multiple-baseline design. International Journal of Psychology and Psychological Therapy, 16(3), 213-233.

Study Type

Randomized multiple-baseline design (SCED - Single-Case Experimental Design) with two-arm structure and group analysis.

Introduction and Theoretical Background

This article investigates the efficacy of a single-session Acceptance and Commitment Therapy (ACT) protocol for disrupting repetitive negative thinking (RNT). The theoretical foundation rests on the premise that worry and rumination constitute maladaptive experiential avoidance strategies. These responses typically emerge as the initial reactions to fear or incoherence, extend negative affect, and generate an inflexible behavioral repertoire characterized by additional avoidance strategies.

The authors, building on Relational Frame Theory (RFT) and previous work by Luciano et al. (2011, 2012, 2016), propose that the triggers for worry and rumination are organized hierarchically. From this perspective, directing therapeutic efforts toward the trigger at the apex of the hierarchy—specifically, self-referential relations or the self-hierarchy—would substantially strengthen intervention effects. This study represents an initial step in evaluating ACT protocols specifically designed to disrupt repetitive negative thinking in emotional disorders.

Participants

The sample comprised N=11 participants (2 men, 9 women) with a mean age of 22.18 years (SD=4.40, range=18-32). Participants were recruited through social media advertisements. Inclusion criteria required participants to report being entangled in thoughts, memories, and worries for at least 6 months, causing significant interference in at least two life domains.

Regarding demographic and educational characteristics, 9% completed mid-level education, 55% were undergraduate students, and 36% were college graduates. With respect to baseline mental health status, 82% (9/11) scored above the GHQ-12 cutoff for minor mental disorders. On the DASS-21 at baseline assessment, 8 participants showed clinically significant scores for depression, 8 for anxiety, and 10 for stress. Mean scores on repetitive negative thinking, experiential avoidance, cognitive fusion, and valued living measures fell within the clinical range.

Design and Procedure

The study employed a two-arm randomized multiple-baseline design with two cohorts. Cohort 1 (participants P1-P6) had baseline periods ranging from 5-13 days, while Cohort 2 (participants P7-P11) had baselines ranging from 7-17 days. Assignment of baseline durations was randomized within each cohort. Importantly, Cohort 2 functioned as a waitlist control group to evaluate intervention effects in Cohort 1, strengthening the internal validity of the design.

Description of the Intervention

The one-session ACT protocol (~75 minutes) was based on Relational Frame Theory (RFT) and prior work on psychological flexibility and self-formation (Luciano et al., 2011, 2012, 2016; Törneke et al., 2016). The intervention pursued four main objectives:

1. Functional analysis: Identify the triggers for worry and rumination, as well as the experiential avoidance strategies that maintain these behavioral patterns.

2. Creative hopelessness: Promote recognition of the counterproductive ineffectiveness of worry, rumination, and other avoidance strategies as attempts to manage the problem.

3. Values clarification and commitment: Facilitate identification of authentic personal values and behavioral commitment toward actions aligned with these values, despite the presence of aversive thoughts and emotions.

4. Cognitive defusion training: Introduce defusion techniques through a hierarchical frame with deictic perspective (deictic I), enabling participants to alter their relationship with automatic negative thoughts.

Outcome Measures

Outcome measures included both primary and secondary assessments:

Primary Measures:

• Daily repetitive negative thinking self-monitoring (0-10 scale)
• PSWQ-11 (Penn State Worry Questionnaire)
• RRS-SF Brooding subscale (Ruminative Responses Scale)
• ATQ-8 (Automatic Thoughts Questionnaire - frequency of negative thoughts)

Secondary Measures:

• GHQ-12 (General Health Questionnaire)
• DASS-21 (Depression Anxiety Stress Scale)
• AAQ-II (Acceptance and Action Questionnaire)
• CFQ (Cognitive Fusion Questionnaire)
• VQ (Valued Living Questionnaire) - Progress and Obstruction subscales

Assessments were conducted at multiple time points: baseline (biweekly), post-treatment, 2-week, 4-week, and 6-week follow-up.

Statistical Analysis

The statistical analysis employed multiple complementary strategies:

1. JZS+AR Bayesian hypothesis testing: Used for overall analysis, providing a Bayes factor (Bar) contrasting the no-intervention versus intervention hypotheses. A Bar>1 supports the null hypothesis (no effect), while Bar<1 indicates evidence favoring the intervention effect. Standardized mean difference (δ) was also calculated.

2. Tau-U nonparametric statistic: Ranges from -1 to 1, indicating the percentage of data showing improvement between phases. Useful for single-case analysis with baseline trend considerations.

3. Within-participant analysis: Application of the JZS+AR model to biweekly data and calculation of within-participant Cohen's d, averaging baseline with 2-week, 4-week, and 6-week follow-ups.

4. Clinically significant change (CSC): Application of Jacobson & Truax (1991) criteria, including reliable change index (RCI) and crossing of clinical cutoff points.

Treatment Integrity

Researchers implemented rigorous treatment integrity controls. Each intervention was observed through a Gessell camera by two independent observers (trained undergraduate students). Both observers confirmed that all interventions followed the established protocol faithfully.

Results

General Clinical Description (Table 3)

At baseline, 9 of 11 participants scored above the GHQ-12 cutoff for minor mental disorders. DASS-21 scores showed: moderate depression in 5 participants, mild anxiety in 4 participants, and mild-to-moderate stress distributed across participants. At 6-week follow-up, only 1 of 11 participants scored above the GHQ-12 cutoff. DASS-21 severity levels decreased substantially.

Daily Repetitive Negative Thinking Self-Monitoring (Figure 2)

Most participants demonstrated elevated variability during baseline. Level changes were observed at post-treatment assessment for 4 participants (P2, P3, P4, P6), while another 4 participants (P5, P7, P9, P10) showed level changes during follow-up.

JZS+AR analysis revealed that 7 of 11 participants (64%) demonstrated Bar<1, indicating that the data were more consistent with an intervention effect hypothesis. Regarding the Tau-U statistic, 8 of 11 participants (73%) showed statistically significant improvements. Individual δ values ranged from -.27 to 5.41, reflecting considerable variability in effect magnitudes. Individual Tau-U values ranged from -.14 to .97.

Significant Change in RNT-Related Measures (Table 4)

• Self-monitoring: 73% showed clinically significant change (CSC)
• PSWQ (pathological worry): 64% CSC
• RRS-SF Brooding subscale: 73% CSC
• ATQ-8 (negative thoughts): 91% CSC

Notably, 9 of 11 participants (82%) demonstrated significant changes in at least 50% of RNT measures. Participants P1 and P11 exhibited the most modest changes. This pattern suggests the intervention was effective for the vast majority of the sample, although with important individual variability.

Self-Report Measures (Table 5): Group Means and Within-Condition Cohen's d at 6-Week Follow-Up

Primary Measures:

• PSWQ: Baseline M=36.79 → 6-week M=26.00. d at 2 weeks=1.14, 4 weeks=1.12, 6 weeks=2.15
• RRS-SF Brooding: Baseline M=13.06 → 6-week M=8.73. d at 2 weeks=.89, 4 weeks=1.43, 6 weeks=1.86
• ATQ-8 negative thoughts: Baseline M=21.45 → 6-week M=12.45. d at 2 weeks=.98, 4 weeks=.90, 6 weeks=1.61

Secondary Measures:

• GHQ-12: Baseline M=15.29 → 6-week M=6.82. d at 2 weeks=1.71, 4 weeks=1.20, 6 weeks=1.71
• DASS Total: Baseline M=23.07 → 6-week M=11.91. d at 6 weeks=1.62
• DASS-Depression: d at 6 weeks=1.12
• DASS-Anxiety: d at 6 weeks=.87
• DASS-Stress: d at 6 weeks=2.09
• AAQ-II: Baseline M=29.65 → 6-week M=18.82. d at 6 weeks=2.09
• CFQ: Baseline M=32.03 → 6-week M=19.36. d at 6 weeks=2.23
• VQ Progress: d at 6 weeks=.77
• VQ Obstruction: d at 6 weeks=2.35

Clinically Significant Change (CSC)

At 6-week follow-up, 8 of 11 participants (73%) achieved CSC on the PSWQ and frequency of negative thoughts. For brooding, 4 of 11 (36%) achieved CSC. Regarding general emotional symptoms, CSC ranged from 46% (DASS-21 total) to 82% (GHQ-12). Notably, effect sizes generally increased over time, particularly between 4-week and 6-week follow-up assessments.

Discussion

The results were highly promising. All participants improved on at least one of the four repetitive negative thinking measures, and nine of the eleven improved on three or more measures. Effect sizes were very large at 6-week follow-up, comparable to complete psychological interventions reported in the literature (e.g., Hanrahan et al., 2012).

A noteworthy finding was that effects increased over time, particularly between 4-week and 6-week follow-up, suggesting that participants continued to benefit during the follow-up period. The authors propose three reasons why this single-session intervention produced such large effects:

1. The protocol addressed three angles of psychological flexibility according to Törneke et al. (2016), providing a multifaceted intervention within a limited timeframe.

2. The intervention focused on disrupting the first and most pervasive reaction to triggers (worry and rumination), rather than working directly with the triggers themselves.

3. There was an emphasis on identifying and working with the trigger at the apex of the self-hierarchy, reflecting theoretical sophistication grounded in RFT.

The pattern of effects increasing over time is consistent with the theoretical model that participants continued to practice and refine their skills in disrupting repetitive negative thinking during the follow-up weeks.

Study Strengths

The study presented several important methodological strengths:

• A two-arm randomized multiple-baseline design combining the strengths of single-case studies (detailed analysis of individual change) with group analysis.
• Rigorous treatment integrity control through independent observers.
• Multiple outcome measures, including both daily self-monitoring and standardized instruments.
• Sophisticated statistical analysis incorporating both Bayesian and nonparametric approaches.
• A 6-week follow-up period allowing evaluation of whether effects maintained or increased over time.

Study Limitations

The authors acknowledge several limitations:

• Small sample size (N=11), limiting generalizability of findings.
• Absence of diagnostic interview, so diagnoses were not formally confirmed.
• Relatively short follow-up period (6 weeks), insufficient to evaluate long-term effect stability.
• Single therapist conducting all interventions, which could have introduced therapist bias.
• The effects may be comparable to those of a complete 6-8 session intervention, as noted in the literature.

Significance and Contribution

This study contributes valuable evidence that brief, structured protocols can effectively disrupt repetitive negative thinking and produce clinically meaningful improvements in emotional symptoms. The theoretical integration of hierarchical self-structures and cognitive defusion from Relational Frame Theory provides a sophisticated conceptual foundation for brief interventions targeting transdiagnostic processes across emotional disorders. The methodology combining single-case experimental design with group-level analyses and effect sizes demonstrates robust evidence that warrants further investigation of brief, targeted treatment approaches in clinical psychology.

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