Reality monitoring and motor memory in checking-prone individuals
Zermatten A, Van der Linden M, Laroi F, Ceschi G;
Commented by , 23 Jun 2006
Background
There may be a deficit in motor memory and reality checking in patients presenting with the checking subtype of obsessive-compulsive disorder (OCD).
Aims of the study
To look for differences in motor memory and reality monitoring between checking-prone and nonchecking-prone subjects.
Method
Two groups of undergraduate students were created based on their checking sub-scores on the revised form of the Obsessive-Compulsive Inventory (OCI-R): a group of 19 checking-prone students and a group of 35 nonchecking-prone students. Participants were asked to encode 60 actions in five different conditions: a motor (MOTOR), an imagined motor (I.MOTOR), a visual (VISUAL), an imagined visual (I.VISUAL), and a verbal (VERBAL) encoding condition.
Following encoding, participants were asked to identify the encoded actions amongst a group of actions comprising 60 new (filler) actions in addition to the old (encoded) actions, and to evaluate the degree of certainty of their response. In addition, all participants were evaluated for differences in terms of dissociation (using the Dissociative Experiences Scale or DES), depression (using the Beck Depression Inventory or BDI) and anxiety (using the Spielberger State-Trait Anxiety Inventory or STAI).
Results
In comparison with nonchecking-prone subjects, checking-prone subjects (1) had fewer hits on motor-encoded actions and (2) more often confused actions they had performed with actions the experimenter had performed. In addition, there was a correlation between scores on the checking subscale of the OCI-R, DES total score and task indices.
Professor Pull's comments
According to the memory deficit hypothesis of OCD, the checking compulsions observed in patients with the checking sub-type of the disorder could be attempts to compensate for real or imagined forgetfulness. Studies on the link between checking and memory problems have, however, produced equivocal results. In particular, most studies have been unable to detect a general memory deficit in patients with OCD.
Most studies that have investigated the memory deficit theory of OCD have, however, dealt exclusively with verbal memory. According to a growing field of investigations, the checking observed in OCD may in fact be linked to an impairment in the processing of non-verbal information, concerning in particular motor stimuli that involve the individual's own actions, and to an impairment in reality monitoring i.e. an impairment in the capacity to discriminate between perceived and imagined events.
According to Ecker and Engelkamp (ref. 1), the pathological doubt that leads to the checking behaviour in OCD may be due to the presence of a deficit in encoding or retrieving motor information and to a difficulty in distinguishing memories of actions performed from memories of imagined action.
The results of the present study support the presence of a deficit in motor memory as well as in reality monitoring in checking-prone subjects. They also suggest that the issue of deficits in motor memory and in reality monitoring in the checking sub-type of OCD is more complex than had previously been presumed. In particular, these deficits may be influenced by a tendency to dissociate.
References
1. Ecker W & Engelkamp J. (1995). Memory for actions in obsessive-compulsive disorder. Behavioural and Cognitive Psychotherapy; 23; 349-371