Patients suffering from Obsessive-compulsive disorder (OCD) tend to check repeatedly and after checking episodes they tend to be uncertain about their memory for checked events. It seems plausible that memory distrust motivates checking, but why checking is repeated and why one check is not enough to reassure the patient is uncertain. To study this, an interactive computer animation displaying light bulbs or gas rings was developed and healthy participants were asked to engage in repeated checking. In five separate experiments we found that repeatedly checking the same class of items resulted in sharp decreases in detail and vividness of memory of the checked events while the accuracy of the memory remained intact. The phenomenological quality of the experienced memory distrust was highly similar to the ambivalence OCD patients tend to report about their memory after checking. Furthermore, there were some indications that repeated checking not only undermines trust in memory, but may also reduce the sense that one acted responsibly. The experimental preparation may be used as a model for OCD checking. The study suggests that repeated checking is sufficient to cause paradoxical effects on memory trust and that repeated checking is a counterproductive safety strategy.