Adult Ss attempted to solve logical deductive reasoning problems that varied systematically in amount of information presented. Methods Ss employed in representing the problem were classified into five main types or modes. The proportion of Ss using a matrix mode of problem representation increased moderately with problems containing large amounts of information. The performance of Ss using a matrix mode of representation suggested that this advantage is related to ease of applying and/or storing the results of logical operations in such a problem space rather than to any facilitative effects of encoding processes. Specific limits to normal processing are hypothesized.