Cognitive bias modification research has grown exponentially since the first studies appeared approximately a decade ago and there is plenty of room for continued growth. To address the limitations of the current available data, we need CBM studies comprising of: first, large RCTs with intent-to-treat analyses, specified a priori primary outcomes and follow-up data; second, tests of proposed mediators and moderators; third, data on patient acceptability and satisfaction; and fourth, independent measures of attention and interpretation in order to examine the generalization of cognitive changes, including neural correlates. Including multiple behavioral and neural measures of cognitive processing may also provide information about whether CBM affects a genuine cognitive change or a conditioned response. Since the vast majority of CBM studies assessed cognitive changes with the same type of task used in training, it is impossible to know whether participants learned a task-specific response or if attention and interpretation processes genuinely changed.
In addition, there are a number of other important cognitive vulnerabilities in emotional disorders that may be targeted by CBM. For example, promising results have been found for modifying memory in depression [97
]. In addition, Clerkin and Teachman developed a CBM-I for individuals with high OCD symptoms in which scenarios focused on pathological beliefs in OCD (e.g., need for control over thoughts, importance of thoughts and intolerance of uncertainty) [98
]. Thus, scenarios focused on the interpretation of the meaning of an intrusive thought (‘having this thought means I’m crazy/normal’), rather than the content of the thought. Such extensions of CBM-I may be adapted for other disorders with similar maladaptive beliefs, such as GAD. Researchers hoping to develop CBM-I tasks for clinical populations might consider approaches such as this in order to cause meaningful change to maladaptive cognitive processing, in addition to targeting the interpretation of specific situations. Future research will reveal whether it is possible to modify these additional cognitive processes in clinical populations, as well as whether targeting multiple vulnerabilities simultaneously is superior to targeting a single bias.
There are a number of issues involved in determining the ideal protocol. First, identifying both the ideal and minimum dosage schedule for therapeutic benefit will be important. Various multi-session protocols have been tested with positive results (e.g., daily vs weekly administration). However, only one protocol (eight sessions over 4 weeks) has been tested in clinical samples. These protocols produced effect sizes within the range of existing treatments in less time and with no clinician contact. It is possible that increasing the dosage of CBM may further enhance the magnitude of effects, but this hypothesis awaits testing.
Another interesting future direction will be development of new CBM paradigms or combinations of paradigms that may address the limitations of current CBM tasks (e.g., lack of generalization and low credibility). Although the dot probe task is the most commonly used CBM-A task, a number of studies have used a face in the crowd paradigm. In each of these tasks, acquiring an attention bias away from threat will facilitate performance. However, each task may be modifying different components of attention bias, and we do not know if one task is superior to another. Moreover, patients may prefer one task over the other. Similar issues exist in CBM-I, in which most studies have used the same scenario paradigm.
Questions also remain about the ideal stimuli. We do not know whether personalized stimuli are superior to standard stimuli sets. In addition, some studies have tested dynamic CBM protocols that begin with neutral stimuli and gradually become more positive over the course of several sessions [77
]. Most multisession protocols presented the same stimuli in each session. It is unclear whether repeated practice with the same stimuli is superior to introducing new stimuli. The latter could potentially increase generalization of changes and patient engagement.
Future research may inform the treatment rationale provided to patients. It is currently unclear exactly what patients should be told regarding the purpose of CBM tasks and the task instructions. For example, Krebs et al.
found that informing participants that the probe will always appear in the location of a particular type of word enhanced CBM-A’s effects on attention and worry in nonanxious individuals [49
]. However, MacLeod et al.
found that providing explicit instructions diminished effects on anxiety [99
]. In CBM-I, explicit instructions have typically not been provided. However, given the more explicit nature of these tasks, participants are very much aware that scenarios ended in either a positive or negative manner [69
]. Moreover, participant knowledge of the scenarios’ valence partially mediated the effect of training group on interpretation bias. Thus, it seems important to investigate how providing this explicit knowledge to participants prior to CBM-I may affect changes in interpretation and anxiety.
Finally, a principal future direction will be identifying appropriate therapeutic uses of CBM. Owing to CBM’s unique features (e.g., standardized computerized delivery, no therapist contact, low demands on patients and brevity), there are a number of potential clinical uses. First, CBM has demonstrated promise as a stand-alone treatment for GSP and GAD. CBM as a stand-alone treatment would provide individuals with anxiety disorders with a new treatment option. Having more options may be beneficial for patients who do not respond to or cannot access current treatments, for patients or providers who find existing treatments unacceptable and for personalized medicine.
Cognitive bias modification may also have utility as an adjunctive intervention or as an option in stepped care treatment. It is possible that some patients may respond better to CBT if they also receive CBM. Should CBM improve attentional control, it may help patients better engage in exposures. It may assist those patients who get ‘stuck’ in cognitive restructuring by bypassing some of their automatic mental habits. Similarly, CBM could be an adjunct to pharmacotherapy. CBM may also prove useful in relapse prevention following treatment, as it directly targets cognitive vulnerabilities. Currently, we have no evidence regarding these potential uses of CBM, and future research examining CBM as adjunctive treatment is needed.
An exciting potential application of CBM is in prevention. Studies have already demonstrated that CBM can buffer healthy and at-risk individuals from stressful situations [45
]. Moreover, studies in children [68
] and adolescents [100
] demonstrate that cognitive biases are malleable in youth. At-risk children and adolescents are particularly important populations for CBM to target given that many anxiety disorders onset during this time. In addition, given that children and adolescent brains are developing, intervening during this period may enhance CBM’s effects compared with attempting to modify long-standing mental habits in adults.
Another issue in determining the best uses of CBM involves dissemination. Several studies have demonstrated that CBM can be delivered at home using online programs, which would enhance the accessibility of treatment. However, at-home protocols have not been tested in clinical samples, which need more attention and clinical monitoring. Preliminary data suggest that while patients appreciate the convenience of an at-home treatment, they also recognize the benefits of coming to an office (e.g., quiet place, scheduled time and social interaction) [85
]. Should CBM be disseminated as a self-help intervention in the home, it will be important to determine whether CBM is better (i.e., more efficacious, easier to use and more acceptable) compared with existing self-help interventions (bibliotherapy and computerized CBT).