Enhanced visual latent inhibition in obsessive–compulsive disorder

Background: Latent inhibition (LI) is the slowed acquisition of a learned response to a conditioned stimulus (CS), that occurs if that CS has previously been experienced in a noncontingent setting. This retarded acquisition is thought to occur because, due to the previous noncontingent experience, an individual must “unlearn the irrelevance” of the CS, before learning its new association to the unconditioned stimulus. A previous report using an auditory paradigm did not detect abnormal LI in obsessive–compulsive disorder (OCD) subjects; this auditory LI task included a difficult acquisition phase, which made it relatively insensitive to detecting abnormally elevated LI (i.e., slowed “unlearning”). Methods: We assessed LI using a highly sensitive computerized visual LI paradigm in 63 carefully screened control subjects and in 48 patients with OCD. Results: Compared to controls, OCD subjects exhibited significantly more LI; if “preexposed” to a to-be-CS, OCD subjects required significantly more trials to learn a new association to that CS, compared to control subjects. This pattern was particularly evident in unmedicated OCD subjects. Conclusions: The inflated impact of preexposure on LI response acquisition in OCD subjects may be a quantitative measure of their tendency to remain “stuck in set” in this cognitive task.