A final point concerns timing and quantity of information. Psychologists have suggested that concentration is reduced after about twenty minutes without a break or a change in activity. Furthermore,audiences should not be overburdened with technical details or given too many facts to remember. It is claimed that to ask people to remember more than three things in a five minute talk is too much. Some say that seven is the maximum number of any length of presentation. Any such calculations are probably not very reliable, but every speaker needs to think about exactly how much information of a particular type a specific audience is likely to absorb and to plan accordingly.