Thevenot, C.
Department of Psychology, University of Geneva, Geneva, Switzerland
The rationale of the operand recognition paradigm (ORP) is to infer the arithmetic strategies used by individuals from the time they take to recognize the operands of a problem after they have solved it (Thevenot, Castel, Fanget, & Fayol, 2010). This rationale is motivated by the fact that algorithmic procedures degrade the memory traces of the operands, whereas they remain intact after a solution process by retrieval of the result from long-term memory (Thevenot, Barrouillet, & Fayol, 2001). First, we will describe the main results obtained with the ORP on mental addition and subtraction. We will show that, whereas individuals with low and high abilities in arithmetic use the same strategies for small and large problems (i.e., retrieval and calculation procedures respectively), they differ in the way they solve medium problems (e.g., 8 + 5 or 13 - 8). While higher-skilled individuals can retrieve the result of such problems from long-term-memory, lower-skilled individuals have to resort to reconstructive strategies. Second, we will present an alternative interpretation of our effects, which has been formulated by Metcalfe and Campbell (2010; in press). The authors suggest that the differences we obtain in recognition times between small and large problems could be due to difficulty-related switch costs rather than strategy use. We will explain why this alternative interpretation is a very bad candidate in order to account for our results.