Selecting between competitors in multiplication tasks: An explanation of the errors produced by adolescents with learning disabilities

Two experiments were conducted in order to determine the nature of the difculties encountered by learning disabled (LD) adolescents in the resolution of multiplication problems (a 3 b, where a and b vary between 2 and 9). A response production task (Experiment 1) revealed that the incorrect responses generally belonged to the table of one of the two operands, and that the order of difculty of the problems was the same for the LDs as for normal children, adolescents, and educated adults as reported in the literature. This result suggests that the difculties are not solely due to memory problems. Experiment 2 tested the hypothesis that these difculties were caused by a problem in inhibiting the incorrect responses from a set of possible responses. Subjects completed a multiple response task in which the correct response was presented along with three distractors. The level of interference between the correct response and the distractors was varied by manipulating the nature of the distractors (Null Interference, NI: numbers that did not belong to the multiplication table; Weak Interference, WI: numbers belonging to othe