Brainstorming is based on the notion that a group of people can outperform an individual when it comes to creative problem-solving and ideas generation. But you can't just push executives into a room and say: "Be creative."
By providing an environment where the flow of ideas is managed, far greater creativity will emerge.
According to Professor Simon Majaro, director for the Centre for Creativity at Cranfield School of Management, you need at least 60 ideas for one innovation.
An experienced group can be capable of producing 150 ideas in about 20 minutes. From that three or four concepts might undergo a feasibility study until one final idea emerges as the winner.
Banks regularly use brainstorming techniques for new products and also at corporate level. One senior investment banker holds an annual brainstorming session with his team to discuss new products.
"We stay on-site, but sit away from the phones and desk," he says. "It's an open forum and everyone has an input. You pull together as a team."
Other banks use brainstorming at corporate level as a technique for helping executives manage expansion. One City of London bank, which has made a series of acquisitions over the last few years, holds corporate "off-sites", where senior managers meet for two days of presentations and "break-out" sessions.
In the latter, 10 executives, who may barely know each other, sit down with a general question, such as, "How can we work more closely to better serve our customers?" and spend half an hour generating ideas, which are then presented to the other 150 managing directors present.
Not only are the sessions useful ice-breakers, but they also make a lot of individuals focus quickly on the core issues in the bank.
Simon Majaro says that easily-defined topics and problems for which there may be many answers are highly suitable for brainstorming.
Jane Clarke, director of Nicholson McBride, the business psychology consultancy, says, "It's quantity rather than quality that counts. That means that even the most apparently silly ideas should be disclosed."
She also stresses that while the group needs to generate as many ideas as possible, the company must also know how to deal with the output, or the exercise is wasted.
The starting point is to take participants out of their corporate mindsets, says Simon Majaro. So, while you can't sit in the bath, you need to create as relaxing an environment as possible. That might be in a room with comfortable chairs, at a venue away from work or even in the local pub, provided there are no outside interruptions.
Groups might number eight to 10, a leader should be appointed to organise proceedings and a scribe chosen who can write clearly and quickly onto a flipchart or board.
Majaro believes in warming up participants with games and a dummy-run brainstorming session on an unrelated topic. "It's difficult to be creative when you're miserable," he says.
Once relaxed the group is ready to begin. Only now should the topic in question be fully explained it doesn't matter if participants have given it little thought beforehand.
Majaro and Clarke both have two basic rules: first, ideas should flow freely and as quickly as possible and second, the group must suspend judgement of any idea put forward.
Ideas may come slowly at first, with only the extroverts in the group speaking, but gradually as the momentum gets going people lose their inhibitions.
The leader needs to make sure the group stays on the topic and all ideas should be visible.
Sometimes a dip can occur after the first wave of ideas. The group could break briefly for a coffee, but should nevertheless carry on, as the second wave is often more productive, says Clarke.
Participants can be so highly charged that they continue to have ideas for hours or even days afterwards.
A final list of ideas should then be circulated and evaluated. Different screening techniques exist, so participants could vote on the best idea, pick the craziest idea, categorise the ideas into themes or measure the ideas against a list of criteria, such as cost and compatibility.
One bank uses an unusual brainstorming technique. It posts a huge piece of white paper in the coffee area on which is written a question. People scribble down their ideas, unsigned.
At its best brainstorming not only produces a flow of ideas, but also helps a team become more cohesive.
"The adrenalin flows," says one banker. "You are with intelligent and creative people and you walk away feeling you can conquer the world."