Compulsive perseveration: empirical criticism on the mood-as-input model

It has been proposed that the "Mood as Input" model provides an explanation of the perseverative nature of Obsessive Compulsive (OC) behaviour (MacDonald, B. C., & Davey, G. C. L. (2005). A mood-as-input account of perseverative checking: The relationship between stop rules, mood and confidence in having checked successfully. Behaviour Research and Therapy, 43, 69-91). The model implies that task perseveration occurs when individuals (a) experience a bad mood and (b) ask themselves "did I do as much as I can?" In two earlier experiments with healthy participants (MacDonald, B. C., & Davey, G. C. L. (2005). A mood-as-input account of perseverative checking: The relationship between stop rules, mood and confidence in having checked successfully. Behaviour Research and Therapy, 43, 69-91) it was found that when the allegedly critical conditions were met (negative mood and "did I as much as I can?" stop rule) perseveration occurred on a complex text-correction task. This finding was held to support a "mood as input" explanation of compulsive perseveration. It is important to note, however, that perseveration in clinical samples occurs for very simple "tasks" (e.g. closing a door or washing ones hands) and perseveration does not increase efficacy of performance. In the present study we compared the effects of the original task to effects of text correction tasks that were simpler and more OCD-like. The original effects were replicated: the combination of negative mood and the "did I do as much as I can" stop rule provoked perseveration. Meanwhile, "perseveration" was highly functional: the more "perseveration" the more text-errors were detected. Secondly, to the degree that tasks became simpler and more OCD-like, less checking occurred and the effects of the "did I do as much as I can?" stop rule on detection of errors became smaller. The findings raise questions about the validity of the paradigm as a model of OC perseveration.