Generally people in interactive, brainstorming groups produce fewer ideas and ones that are less creative than those same people would if they were working individually, in what is known as nominal groups. Production blocking, the tendency for one individual during a group discussion to block or inhibit other people from offering ideas, is a major reason.
For example, if one person in a six-person group is talking about his or her idea, then the other five people are "blocked" and less able to provide their own creative input. Additionally, production blocking can occur if the same six people are attempting to communicate their ideas at the same time as one another.
When others are talking, group members may not have time to think of an idea, might get distracted, or merely forget about their idea before they have an opportunity to share it. Production block is not the same as either evaluation apprehension or social loafing, two other factors that can cause people to produce fewer ideas in real, interactive groups than those in nominal groups. With evaluation apprehension, individuals may be reluctant to share their suggestions, fearing that they may be negatively criticized. With social loafing, they may not share ideas because they believe other group members will do so instead.