The performance of 32 Ss solving concept-learning problems with the two rules of inclusive and exclusive disjunction was investigated with two kinds of artificial memories. One of the artificial memories gave a relatively high memory-load to Ss and the other gave a relatively low memory-load. Under the low memory-load, the trials to criterion data were almost identical for the two rules. Under the high memory-load condition both rules were more difficult than before and the exclusive disjunction became relatively more difficult than the inclusive disjunction. Some of the recognition-memory error data for individual stimulus items supported a differential memory-interference notion of the difference between the rules under high memory-load. Other recognition-memory error data suggested possible perceptual organization factors as being important.