Two hypotheses, the cognitive capacity hypothesis and the selective attention hypothesis, try to account for the facilitation effects of prior knowledge activation. They appear to be mutually exclusive since they predict different recall patterns as a result of prior knowledge activation. This study was designed to determine whether the two hypotheses are mutually exclusive, or whether they only appear to be diametrically opposed. Two groups of 10 subjects participated in experiments providing support for the two hypotheses. One group, the "problem group," activated knowledge that corresponded with the problem information of a text that described the consequences of fishery policies for a small (hypothetical) village in Portugal. The recall pattern of this group was expected to reflect the predictions of the cognitive capacity hypothesis. The other group (the tourism group) was expected to show the recall pattern predicted by the selective attention hypothesis as group members tried to fill the slots of schema mobilized prior to the study by constantly selecting matching information. Results indicate that both hypotheses could be valid. The problem group showed an increase in new information while recall of activated information was not impaired, as predicted by the cognitive capacity hypothesis. The problem group also recalled more information than did the other group, and their recall protocols showed more relations linking the concepts of the text. Findings indicate that these hypotheses only appear to be mutually exclusive. Two tables contain study data. (SLD)