Mental arithmetic and irrelevant auditory number similarity disruption

Both the mental arithmetic and semantic auditory distraction literatures show task interference from similar items, yet this has not been demonstrated in the common scenario of performing mental arithmetic whilst similar numbers are being spoken. This study attempted to rectify this omission by conducting an experiment in which both the type of irrelevant sound (quiet, similar numbers, dissimilar numbers and non-number speech) and the difficulty of problems (easy and hard) were revealed to affect addition mental arithmetic performance. Specifically, hard problems were solved less often than easy problems and, more importantly, a number similarity effect was observed such that similar irrelevant numbers impaired performance more than dissimilar irrelevant numbers. Results and future research are discussed with respect to both the mental arithmetic and semantic auditory literatures.