Cognitive bias modification (CBM) interventions have grown extremely popular over the last decade, both with researchers, as well as with end-users. The term is an umbrella name for experimental procedures, designed to promote the modification of specific cognitive biases considered critical in the onset and maintenance of psychopathology both in adults and in children.
These procedures are usually tasks delivered via a computer, intended to teach participants, generally without their awareness, to either orient their attention away from threatening stimuli, or to interpret ambiguous situations in a positive or benign manner. In this way, negative biases are presumably modified or at least “de-activated”, which in turn should lead to improvements in negative mood and in symptoms of psychopathology.
In a recent trial reported in the Journal of Child Psychology and Psychiatry, Chan and colleagues started by noting that evidence about the efficacy of CBM interventions for adolescents was mixed and that various methodological issues might have played a role in explaining some of the results obtained by previous studies.
They set out to address these issues in a new study, with an amended control condition, a longer training period, the inclusion of a follow-up and using standardized instead of ad-hoc measures of mood and symptoms.
Participants were 74 adolescents (age range 16-18), randomised to an intervention or control group. The specific type of CBM intervention used targeted interpretation bias; the notion that individuals with symptoms of or vulnerable to mood disorders tend to interpret ambiguous stimuli in a negative, rather than a neutral or positive way.
Participants in both groups were presented with a series of ambiguous scenarios on a computer screen. In the CBM intervention group, each scenario ended with a word fragment that resolved ambiguity in a positive way. In the control group, participants received placebo training in which they were presented with the same scenarios, except that the word fragments at the end did not resolve the emotional ambiguity of the scenario in any way. In both groups, training was self-paced and extended over two sessions, each using 40 training scenarios and 8 “distracter” ones. These latter scenarios were added to make the purpose of the training less apparent and in them participants were prompted to resolve the ambiguity in a negative and neutral way.
The procedure involved a baseline assessment of interpretation bias, positive and negative mood, anxiety and depression, followed by two consecutive sessions of either CBM or control training. Post-intervention, interpretation bias and positive and negative mood were also assessed and participants also underwent an experimental stress task. The week following the intervention, participants gave daily self-ratings of mood and events and were finally assessed again for interpretation bias, positive and negative mood, anxiety and depression.
- Participants in the intervention group reported a greater reduction in negative affect compared to the control group. Also, while an increase in state anxiety at follow-up was apparent in the control group, this did not happen in the intervention group
- However, both groups reported similar changes in interpretation bias (increased positive interpretations, decreased negative interpretations)
- Also, both groups reported reduced depressive symptoms and positive mood, and no changes in trait anxiety
- There were also no group differences in stress reactivity
- After controlling for group differences in training performance, all mood effects disappeared, though the effects on interpretation bias remained
The authors synthesize the results of their study:
This study did not yield evidence to support the effectiveness of two sessions of CBM in healthy adolescents.
They also conclude that:
The results of this study, though not conclusive, highlight that the effect of CBM in adolescents may be much weaker than previously assumed and that wider applications in this age group need to be considered with caution until further evidence emerges.
However, I believe that the authors of this study, while having conducted an important trial, are too soft and focused in their conclusions.
Putting together the results of this sound randomised controlled trial with those of a meta-analysis of CBM interventions for children and adolescents (Cristea et al., 2015), recently reviewed here on the Mental Elf, maybe it’s time to really wonder whether so many resources and research projects should still focus on CBM interventions, despite limited evidence for their effectiveness piling up.
When well conducted trials, one after the other, fail to find effects, maybe it’s time to face the fact that it is very likely there are very limited, if any, mental health benefits for CBM interventions.
- The “dose” of training might have been insufficient, though on the other hand there is no evidence that for children and adolescents a dose effect of number of sessions would exist.
- Participant feedback for the task was mixed, with many reporting it as too long or too stereotyped.
- Participants were unselected so maybe they did not really have negative interpretation biases that could be reduced through training. In the same way, their initial level of anxiety or depression might have been too low for effects to be seen.
Chan, S.W.Y., Lau, J.Y.F., Reynolds, S.A., 2014. Is cognitive bias modification training truly beneficial for adolescents? J Child Psychol Psychiatry. [Abstract]
Cristea, I.A., Mogoașe, C., David, D., Cuijpers, P., 2015. Practitioner Review: Cognitive bias modification for mental health problems in children and adolescents: a meta-analysis. J Child Psychol Psychiatry. doi:10.1111/jcpp.12383 [Abstract]