Three experiments were designed to test the efficacy of ideation procedures that involved alternation of individual and group idea generation sessions (hybrid brainstorming) as compared to traditional individual and group ideation. The hybrid condition led to the best performance in terms of number of ideas generated. This effect was strongest in comparison to the group condition. A meta-analytic comparison involving all three experiments indicated that the hybrid condition outperformed both the alone and the group conditions. Since after each group idea exchange session there was an enhancement in the number of ideas generated in the alone session, the pattern of performance in the hybrid condition supported the cognitive perspective of group creativity (Nijstad & Stroebe, 2006; Paulus & Brown, 2007). Social cues in the form of the co-presence of other participants in the alone condition, the addition of practice sessions to all conditions, and an additional phase did not change the pattern of results. The results of the experiments support the original suggestion by Osborn (1953) that the most effective brainstorming process is one that involves a variation in individual and group ideation.

A number of studies on electronic brainstorming have found that large electronic groups can facilitate the number of ideas generated relative to control groups of similar numbers of solitary performers (nominal groups). Thus far there is no clear evidence for the basis of this facilitative effect. The most likely explanation is that group members benefit from exposure to the wide range of ideas in large groups. Since most electronic brainstorming studies appear to divide the presented ideas into subfolders to avoid overloading participants with too many ideas, this practice may be important for demonstration of a benefit of exposure to a large number of ideas. The present study was designed to assess the role of number of ideas and number of folders on individual idea generation and to eliminate some alternative interpretations for the group size effect. Participants performed an idea generation task on computers while being exposed to either no ideas, 28 ideas, or 112 ideas. The 28 and 112 ideas were presented in either one, four, or eight folders. The results indicated that only the number of ideas factor was important for facilitating idea generation.

This research indicates that collaborative idea sessions can be beneficial in work sessions if the brainwriting paradigm is used with an appropriate alternation of group ideation or review sessions with individual idea generation sessions.

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Three studies examined the role of prior consideration of categories on a brainstorming task. Participants were asked to generate abstract categories before they brainstormed either in groups or individually in Experiment 1. It was expected that generating categories before ideation would be beneficial. However, it was found that category generation harmed the group ideation process. Prior category generation reduced clustering of ideas within categories for groups, which might have led to a decrease in productivity. The last two experiments examined whether groups would benefit by brainstorming one category at a time because this might increase clustering. It was found that sequential category brainstorming helped increase productivity during the ideation process and increased clustering. These studies demonstrate that a prior categorization phase can facilitate subsequent brainstorming because it enhances sub sequent clustering of ideas within categories.