New studies in brain research indicate that during a 20 minute presentation, the time that is spent absorbing and retaining information, or "prime time" for tuning in, is approximately 18 minutes, or 90% of the total presentation time. During a 40 minute presentation the prime time drops to 75% of the total time. Presentations that are 80 minutes in duration only command a 62% audience prime time, which means listeners are in "down time" for 30 of those 80 minutes.

In the interest of efficiency, business presentations should be shorter rather than longer. Presentations or speeches that require a longer format should be designed with 20 minute modules. This involves planning a major change every 20 minutes in the form of a major move on the part of the speaker, a change in the use of technology, or audience involvement.

Christina Kaya is Principal of Kayaco Seminars, specializing in presentation skills development for business. She can be contacted at christina@kayaco.com.