One of several cognitive processes, believed to contribute to the development and maintenance of symptoms across numerous disorders, is difficulties coping with uncertainty. Patients in disorders such as Obsessive Compulsive Disorder, Autism, and Eating Disorders, develop ritualistic and excessive checking behaviours, possibly due to finding even mild or moderate states of uncertainty aversive. Intolerance of Uncertainty (IU), involving difficulties tolerating ambiguous or uncertain situations, has been proposed as a trans-diagnostic process contributing both as a cognitive vulnerability and as a maintaining factor. Research to date has focused almost exclusively on subjective self-report, limiting validity and theoretical understanding of IU and its relation to specific behaviours such as excessive checking. Performance measures that assess certainty seeking and checking behaviours in controlled settings and their possible relation to IU can address such concerns and inform clinical understanding. This talk will discuss such measures, focusing on the observing task, which was developed as a translational operant task in both rodents and humans. Such performance measures can shed light on the development and maintenance of maladaptive certainty seeking behaviours, and offer a bridge between different approaches in psychology to improve understanding and ultimately psychological and pharmacological treatments.