The hypothesis generation process is divided into two phases: the search phase and the decision phase. In the former phase, many possibilities for the hypotheses are considered; and in the latter phase a focal rule is decided upon. In the current study, we investigated the search phase using eye movement data. We detected two types of search strategy: one strategy was a spread-attention search in which participants spread their attention over a broad area in rule space; and the other was a focused-attention search in which participants concentrate their attention on a narrow area in rule space. Results of our experiment showed that the focused-attention search strategy was more effective for rule discovery than the spread-attention search strategy.