title: Passive hand movements disrupt adults' counting strategies.
abstract: In the present study, we experimentally tested the role of hand motor circuits in simple-arithmetic strategies. Educated adults solved simple additions (e.g., 8 + 3) or simple subtractions (e.g., 11 - 3) while they were required to retrieve the answer from long-term memory (e.g., knowing that 8 + 3 = 11), to transform the problem by making an intermediate step (e.g., 8 + 3 = 8 + 2 + 1 = 10 + 1 = 11) or to count one-by-one (e.g., 8 + 3 = 8…9…10…11). During the process of solving the arithmetic problems, the experimenter did or did not move the participants' hand on a four-point matrix. The results show that passive hand movements disrupted the counting strategy while leaving the other strategies unaffected. This pattern of results is in agreement with a procedural account, showing that the involvement of hand motor circuits in adults' mathematical abilities is reminiscent of finger counting during childhood.
authors.affiliation: Department of Experimental Psychology, Ghent University Ghent, Belgium.
authors.forename: Ineke
authors.initials: I
authors.lastname: Imbo
authors.forename: André
authors.initials: A
authors.lastname: Vandierendonck
authors.forename: Wim
authors.initials: W
authors.lastname: Fias