Abstract
This study examines the process underlying multi-digit number judgments. Participants were required to judge which number was the larger from pairs of numbers consisting of two-, three-, or four-digits. In Experiments 1 and 2, the compatibility of the digits in the second, third, or fourth position was manipulated. Analyses carried out for number pairs with different digits in the first position indicated that there was a significant compatibility effect for the second position, but not for the third and fourth positions. In Experiment 3, dummy trials where the number pairs had the same digit in the first position were excluded, and the participants were instructed to make judgments based only on the digit in the first position. The observed compatibility effect for the second position was smaller than that found in Experiment 1. These results suggest that parallel processing of reference digits is limited to the first two positions, and that knowing in advance whether the second-position digit is important for judgments influences the processing of the second-position digit.
