Mindfulness Difficulties in BPD 1
Supplemental Material
Potential fatigue effects within each mindfulness exercise
In order to test whether the difference between individuals with BPD and HCs was more pronounced towards the end of each mindfulness exercise, we conducted the following exploratory post hoc analyses:
We divided each mindfulness exercise into a first and a second part. For the experimenter-prompted mindfulness task, the first part consists of the first 6 trials that last 9 minutes in total. The second partconsists of the last 7 trials that last 11 minutes in total.[1]For the self-prompted mindfulness task, the first partconsists ofthe first 10 minutes and the second part consists of the last 10 minutes.
We then tested for group differences in frequency of mind-wandering and length of mind-wandering for the separate parts of each task, using independent sample t-tests and Mann-Whitney-U tests. In addition, we tested whether there were any differences in performance between the first and the second part of each task using paired sample t-test and Wilcoxon signed rank test. For a summary of descriptive statistics, see supplemental table 1.
Mindfulness and Mind-wandering episodes. In the experimenter-prompted task, BPD patients mind-wandered more frequently than HCs in the first 6 trials(t(51) = 4.68, p.001) and in the last 7 trials(t(51) = 2.36, p = .005). In addition, participants did not mind-wander significantly more frequently in the last 7 trials compared to the first 6 trials in neither group (BPD: t(24) = -0.66, p = .514, HC: t(27) = -2.04, p = .051). In the self-prompted task, BPD patients indicated that they mind-wandered more frequently than HC participants in the first 10 minutes (t(44.9) = 2.88, p = .006) and in the last 10 minutes (t(51) = 2.37, p =.021). Participants did not mind-wander significantly more frequently in the first compared to the last half of the task in neither group (BPD: t(24) = -1.5, p = .15, HC: t(27) = -1.18, p = .25.
Length of mind-wandering.In the experimenter-prompted task, BPD patients indicated that they mind-wandered longer than participants in the healthy control group on the first 6 trials (U = 179, p = .001) and on the last 7 trials (U = 241, p = .04). Participants did not mind wander significantly longer in the last 6 trials than in the first 7 trials in neither group (BPD: U = -1.22, p = .22, HC: U = -1.94, p = .053).
In the self-prompted task, BPD patients mind-wandered longer than HC participants in the first 10 minutes (U = 241, p = .04) but not in the last 10 minutes (U = 279, p = .24). Participants did not mind wander longer in the first 10 minutes than in the last 10 minutes in neither group (BPD: U = -1.39, p = .16, HC: U = -.926, p = .35).
Supplemental Table 1.
Experimenter-prompted task / First 6 trials (9 minutes) / Last 7 trials (11 minutes)BPD / HC / BPD / HC
Mind-wandering Episodes
Mean percent (SD) / 67 %a / 43 %a / 70 %b / 52 %b
Length of mind-wandering Mdn(R) / 2 (2)a / 1 (2)a / 2 (2.5) b / 1.25 (2.5) b
Self-prompted task / First 10 minutes / Last 10 minutes
BPD / HC / BPD / HC
Awareness of Mind-wandering
Sum (SD) / 11.72 (5.53)a / 7.79 (4.25)a / 14.44 (11.36)b / 8.54 (6.29)b
Length of mind-wandering Mdn(R) / 2 (1)a / 1 (1)a / 2 (2) / 1(2)
Note. Group differences in percent of mind-wandering episodes, length of mind-wandering, and awareness of mind-wandering in the first and second half of each task. BPD, individuals with borderline personality disorder; HC, healthy control participants; a and b, pairwise comparisons significant at p.05
[1] As the experimenter-prompted task consists of 13 trials with varying intertrial intervals (in this order: 30s, 120s, 60s, 180s, 30s, 120s, 180s, 30s, 180s, 30s, 180s, 120s, 60s, 60s, 30s), it was not possible to create two or more parts that are exactly of the same length. Consequently, we divided the experiment into two parts that were closest in length and trial number.