Carrying out a sequence of actions is something we do every day without thinking much about it—like when we cook. We first gather ingredients, then clean, chop, and arrange them so they are ready for cooking. Each step follows the previous one, requiring cognitive control to stay on track. But for people with mental health conditions like obsessive-compulsive disorder (OCD), this process can get disrupted. For example, someone with OCD might feel the need to compulsively check if the fridge is closed over and over, making it challenging to move forward and finish cooking. These repetitive behaviors can interfere with even the simplest tasks.
Despite the importance of performing sequences in everyday life, we know little about how they are affected by disorders like OCD. Understanding how these behaviors break down in certain conditions is needed for developing better targeted and effective treatments. This was the focus of the paper published in the Psychonomic Society journal, Cognitive Affective & Behavior Neuroscience, titled “Abstract task sequence initiation deficit dissociates anxiety disorders from obsessive-compulsive disorder and healthy controls,” by Hannah Doyle, Christina Boisseau, Sarah Garnaat, Steven Rasmussen, and Theresa Desrochers (pictured below, Garnaat not shown).
To measure how well people handle abstract task sequences, participants with OCD, anxiety disorders (ANX), and healthy controls (HC) took part in a sequencing task. As shown in the figure below, this task required them to categorize stimuli based on color or shape within simple and complex sequences. The stimuli were simple shapes of circles or squares, either small or large, and red or blue. According to the rules, participants pressed a key to indicate the correct shape or color. There were two types of sequences: simple and complex sequences. For simple sequences, participants had to switch tasks once within the sequence (e.g., by first categorizing shape and then color twice). For complex sequences, participants had to switch tasks twice (e.g., categorize color, shape, shape, then color). Participants had to remember the order and task type (color or shape) per trial.
Reaction times and errors were analyzed to assess differences in cognitive control between OCD, anxiety disorders, and healthy controls. The plots below show the results. The healthy controls did well on the task, as expected. Surprisingly, people with OCD performed the task just as well as healthy individuals. This finding was unexpected because it’s suspected that OCD might interfere with the ability to handle sequences due to repetitive behaviors, like compulsive checking. People with anxiety disorders did not do as well as either the OCD group or healthy controls. They had difficulty starting and managing the sequences, suggesting they may face unique challenges with this type of thinking and task performance.
This clear difference between how OCD and anxiety disorders affect behavior suggests that anxiety disorders might disrupt the brain’s ability to manage sequences more than OCD does. This result is noteworthy because it goes against earlier theories suggesting that people with OCD might have poor task sequence performance due to their repetitive behaviors. The findings point to differences in how OCD and anxiety disorders affect the brain, suggesting that anxiety disorders might be connected to deficits in the brain’s frontal regions, whereas OCD involves different areas.
About the findings, the authors wrote,
“OCD and anxiety disorders are often viewed as clinically and phenotypically similar, but here we show a dissociation in these groups along a novel behavioral axis, abstract sequential control. Abstract sequences are those that are governed by rules or tasks, rather than individual stimuli, such as cooking – it doesn’t matter whether ingredients come from the garden or the refrigerator. Thus, this work may shed light on key, naturalistic behaviors associated with these disorders, have future utility in a clinical setting, and contribute understanding to how we control behavior in our daily lives.”
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Doyle, H., Boisseau, C.L., Garnaat, S.L., Rasmussen, S. A., & Desrochers, T. M. (2024). Abstract task sequence initiation deficit dissociates anxiety disorders from obsessive–compulsive disorder and healthy controls. Cognitive Affective & Behavioral Neuroscience. https://doi.org/10.3758/s13415-024-01207-7
