The current study aimed to investigate the effectiveness for a community sample of an attentional bias task intervention on mood states, as well as the potential mechanisms underlying any observed benefits. Results indicated that both the experimental and control tasks led to improvements in immediate mood states, but these improvements favoured the control task. Additionally, while we observed reductions in DASS symptoms for the experimental condition and increases in DASS anxiety for both conditions, effect sizes were small, raising questions about the practical significance of the task. Unexpectedly, we observed only a small attentional bias in the experimental condition, with day seven latencies strongly associated with day thirty DASS stress.
Engaging in the attentional bias task positively influenced participant mood states, regardless of their assigned condition. However, we did not observe evidence of pre-existing attentional bias in our sample. Such bias only emerged after repeated exposure to the experimental task. Surprisingly, reductions in task performance were associated with increased positive mood states but decreased past-week depressive symptoms, contradicting prior research (Bourke, Douglas, & Porter, 2010). Task performance was related to outcome measurements, indicating mood effects associated with task improvements. Participants with higher pre- and post-task positive mood states exhibited decreased performance at day seven and improved psychological distress symptoms (DASS depression and stress scales) at day thirty.
These findings are complex to interpret. While we expected improved task performance to be associated with immediate mood states and symptom reduction over time (as reported by Bourke et al., 2010), we found that immediate mood improvement occurred after each administration of the control task. Neither task administration correlated with contemporaneous mood states or psychological distress scores (DASS). Our results align with experimental data suggesting initial mood improvement due to transient cognitive control enhancement from directed training (Nejat et al., 2019). However, the lack of persistent training in our design might have limited the duration of the effect. Overall, our findings suggest that any initial attentional bias related to mood or psychological distress was likely absent in our sample, but completion of all time points may have induced a protective bias.
Early research indicates an unreliable relationship between mood and attentional bias. Higher trait anxiety alone was often insufficient to induce detectable bias without additional stressors (e.g., Juth et al., 2005). The emotional valence of the task also played a role in eliciting bias. Dodd et al. (2017) found that anxiety-related task performance deterioration occurred when emotional content was not emphasized. As our tasks didn't aim to induce heightened anxiety and the control task lacked emotional references, our failure to detect initial bias might stem from experimental design limitations rather than a complete rejection of attentional biases. The emergence of attentional biases during the second task administration could be attributed to participants being aware of task difficulty and experiencing performance anxiety absent earlier. Additionally, experimental evidence suggests that attentional biases associated with depressive states are sensitive to specific target-distractor combinations (e.g., Bourke et al., 2010), and so our use of happy faces among angry and our lack of investigation into comorbid states has likely reduced the sensitivity of our design to detect biases.
It is also possible that our missing data is informative. We observed that our participants who dropped out of the study by day thirty reported significantly greater depression and worse mood states than those who completed all timepoints (DASS Depression: t(136) = 2.81, p = .005, MD = 2.19). Given that the level of psychological distress as measured by the DASS was universally low, the apparently paradoxical finding seems likely to be a spurious correlation. In contrast, the change in immediate mood state was far larger, as was the baseline difference between participants who dropped out and those who completed (t(94) = -7.418, p < .001, MD = 46.35). This large difference is predominantly driven by the experimental condition; participants who dropped out before the day thirty timepoint consistently reported better mood states than those who completed.
This study had several limitations. The small effect sizes in the experimental task compared to the control task question its practical significance and clinical potential, especially considering the negative effect on psychological distress. The lack of correlation between task performance and changes in mood or distress implies an additional, unknown mechanism, contrasting the successful use of the control task. Some studies suggest that completing simple, challenging tasks can temporarily reduce anxiety (Pine et al., 2020), which may explain the benefits of the control task. The absence of emotional content or feedback might promote relaxation, leading to immediate but transient benefits without durable distress reduction. Future research should explore more intensive intervention periods and repeated administrations within shorter intervals for improved mood effects. The inability to detect attentional bias initially may be due to insufficient distress in the sample, with subsequent exposures inducing the bias. This suggests heightened vigilance characteristics (Matheson, Wade, & Yiend, 2019; Moussally et al., 2016). Our findings raise questions about underlying mechanisms and advocate for further investigation into cognitive training for mood improvement. Finally, a major limitation of the study is the substantial attrition observed over time, with roughly 50% of participants lost at each timepoint. Although there was no discernible demographic pattern of missingness, this raises concerns about the generalisability of the findings and the potential for selection bias.
Our study implies that cognitive training interventions may have some potential for improving mood states, but further research is needed to better understand the effectiveness of specific interventions and the mechanisms underlying their benefits. Our finding that the control condition was particularly effective for improving mood states suggests that mechanisms of mood state change through visual search paradigms might be unrelated to attention. In conclusion, while both the experimental and control tasks led to immediate improvements in mood states, the control task was more effective. Although we observed statistical superiority of the experimental condition for DASS symptoms, effect sizes were small, inviting replication and further research to validate the practical significance of the task. The study had several limitations, particularly high attrition rates, but suggests that cognitive training interventions may have potential for improving mood states. Further research is needed to better understand the effectiveness of attentional bias tasks as an intervention for mood states and dysfunction, and the mechanisms underlying their benefits.