The use of procedural knowledge in simple addition and subtraction problems

► There is no strong evidence in the literature that the answers of small addition are retrieved from long term memory. ► A coherent view from the data of the literature could also be that small additions are solved by procedures. ► We show that presenting the + sign 150 ms before the operands in very simple addition problems primes the answer. ► On the contrary, presenting the × sign 150 ms before the operands in multiplication does not prime the answer. ► We conclude that procedures are pre-activated by the arithmetic sign for simple addition but not for multiplication.