Drawing upon the Search for Ideas in Associative Memory (SIAM) model as the theoretical framework, the impact of heterogeneity and topic relevance of visual stimuli on ideation performance was examined. Results from a laboratory experiment showed that visual stimuli increased productivity and diversity of idea generation, that relevance to the topic and homogeneity among visual stimuli increased productivity, whereas homogenous but topic irrelevant stimuli suppressed both productivity and idea diversity. The findings show that the SIAM model applies to visual, as well as to textual, stimuli, and extend the model's arguments with respect to cognitive interference and fixation effects.