Simple arithmetic processing: surface form effects in a priming task.

Models of numerical processing vary on whether they assume common or separate processing pathways for problems represented in different surface forms. The present study employed a priming procedure, with target naming task, in an investigation of surface form effects in simple addition and multiplication operations. Participants were presented with Arabic digit and number word problems in one of three prime-target relationships, including congruent (e.g., '2+3' and '5'), incongruent (e.g., '9+7' and '5') and neutral (e.g., 'X+Y' and '5') conditions. The results revealed significant facilitatory effects in response to congruent digit stimuli at SOAs of 300 and 1000ms, in both operations. In contrast, inhibitory effects were observed in response to incongruent word stimuli in both the addition and multiplication operations at 300ms, and in the addition operation at 1000ms. The overall priming effects observed in the digit condition were significantly greater than in the word condition at 1000ms in the multiplication operation and at 300ms in the addition operation. The results provide support to separate pathway accounts of simple arithmetic processing for problems represented in different surface forms. An explanation for variation in processing due to differences in access to visual and phonological representations is provided.