Singing Your Negative Body-Related Thoughts: A Randomized Controlled Trial of a New Cognitive Defusion Strategy
Phase: NA
Conditions: Body Dissatisfaction
Sponsor: York University

 
 
 
 
 
 
Singing Your Negative Body-Related Thoughts: 
A Randomized Controlled Trial of a New Cognitive Defusion Strategy 
 
Study Protocol and Statistical Analysis Plan 
NCT03646305 
 
August 28, 2019 
 
 

Study Protocol  
 
Ethics approval was received from the York University Human Participants Review 
Committee. Eligible participants (i.e. individuals who endorsed restrained eating attitudes and 
behaviours) gained access to this study through the university undergraduate research participant 
pool’s online portal. Individuals who signed up to participate in the study made two visits to the 
lab at York University. The visits were one-week apart; Part 1 was approximately 60 minutes 
long and Part 2 was approximately 30 minutes long. After providing written informed consent, 
Part 1 began with participants completing the visual analogue scale for mood and body 
dissatisfaction (see Appendix A) and measures of state body image (BISS). Next, participants 
underwent a body dissatisfaction induction task whereby they were asked to evaluate, for two 
minutes, the photograph the researcher took of them, paying particular attention to “bothersome” 
parts. After the body dissatisfaction induction task, participants completed the dissatisfaction 
induction measure to ensure all conditions were equally activated by this task (see Appendix B). 
A target thought was determined by asking the participant “what is a negative self-statement that 
comes to mind when you think about your body?” Participants then completed the thought 
evaluation in response to that target thought (see Appendix C). Next, participants were randomly 
assigned to an experimental condition, following simple randomization procedures (computer 
generated randomization lists from randomizer.org; Urbaniak & Plous, 2017). The 
randomization schedule was generated by a researcher otherwise uninvolved in the trial. 
Participants were assigned to one of four conditions: (1) verbally repeating out loud negative 
body-related thoughts (experimental), (2) singing negative body-related thoughts (experimental), 
(3) verbally repeating out loud body-unrelated thoughts (control), or (4) singing body-unrelated 
thoughts (control). Each participant’s randomized assignment was unknown to the investigator 
until this point in the procedure and participants were not informed of which conditions were 
experimental or control until the debriefing at the end of Part 2 so as to minimize demand 
characteristics. Participants in all conditions were then given a rationale on cognitive defusion 
(adapted from Masuada et al., 2004; see Appendix D), underwent a training session with a 
neutral word (i.e. silk), and were asked to rate the credibility of the rationale (see Appendix E). 
 
As a training session in cognitive defusion, those in the experimental conditions repeated 
the technique saying or singing their negative body-related target thought. Those in the 
experimental verbal repetition condition repeated the thought out loud and as quickly as possible 
for 60 seconds. Those in the experimental singing condition sang the thought to the tune of 
‘twinkle, twinkle, little star’ for 60 seconds. Those in the control conditions followed the same 
procedures for a non-body related thought (i.e. “I am talking” in the verbal repetition condition 
and “I am singing” in the singing condition) that should not evoke thoughts about their body. 
After this training, participants once again completed measures of mood and body 
dissatisfaction, thought appraisals (i.e. believability, negativity, discomfort, willingness, and 
avoidance), and state body image, as well as measures of self-esteem, cognitive defusion (CFQ) 
and demographics. 
 
All participants were asked to practice their assigned strategy as homework two times per 
day for one week and to complete the body satisfaction measure after each practice session (see 
Appendix F). They returned to the lab for Part 2 exactly one week after Part 1, where they 
completed measures of mood and body dissatisfaction, thought appraisals, state body image, 

state self-esteem, thought-shape fusion (TSF-LF), cognitive defusion, and a self-report measure 
of homework adherence (see Appendix G). Height and weight were measured with participants 
standing backwards on the scale. Finally, participants received an oral and written debriefing that 
outlined the purpose of the study and contact information if they have any additional questions 
following the study and/or the findings of the study upon completion. They were offered the 
opportunity to ask any questions and given a list of resources for support of students’ mental 
health. See Figure 1 for a visual schematic of the procedure. 
 
Figure 1  
Visual Schematic of Procedure  
 
 

Statistical Analysis Plan  
 
A 2 (Intervention: experimental, control) × 2 (Activity: singing, verbal repetition) × 3 
(Time: baseline, post-intervention, follow-up) mixed ANOVA was used for most measures, with 
a paired sample t-tests with a Bonferroni correction to probe significant findings. For the CFQ 
and SSES, a 2 (Intervention: experimental, control) × 2 (Activity: singing, verbal repetition) × 2 
(Time: post-intervention, follow-up) mixed ANOVA was used with a paired sample t-tests with a 
Bonferroni correction for significant findings. A mediation analysis was used to examine the 
effects of homework compliance, indicated by the total number of seconds of defusion practiced 
over the course of the week, on each outcome measure. Finally, a moderation analysis was used 
to examine the effects of thought-shape fusion on each outcome measure.