Hypersensitivity-to-interference in memory as a possible cause of difficulty in arithmetic facts storing.

Difficulty in memorizing arithmetic facts is a common problem encountered in people suffering from dyscalculia. We suggest that hypersensitivity-to-interference in memory could account for this profile of difficulty. We first report the description of a patient showing a deficit in storing multiplication facts together with a hypersensitivity-to-interference. We hypothesized that similarity between arithmetic facts would provoke interference and that learners who are hypersensitive-to-interference would encounter difficulties in storing arithmetic facts in memory. This hypothesis was first tested in 4th grade children: Children with weak arithmetic facts learning showed higher sensitivity-to-interference in memory compared to the control group. We then showed in adults, that this hypothesis specifically explained difficulties in arithmetic facts solving but not in a global math test. Finally, we created a measure of the proactive interference weight for each multiplication problem and showed that it accounted for both difference of performance between the problems and between individuals