In November last year I wrote about my concerns about powerpoint misuse in an entry called do you hand out your handouts. Emeritus Prof John Sweller has presented research showing that powerpoints are not really good pedagogical tools.
Basically the human mind cannot effectively take in, process, understand and remember information which comes simultaneously from two sources. Therefore the lecture two sources of input (heavy powerpoints and the lecturer’s voice) becomes a cognitive overload for the short-term memory.
This work is part of his development of cognitive load theory (wikipedia).
Sweller writes on his website:
Cognitive load theory (e.g. Sweller, 1988; 1994) is an instructional theory generated by this field of research. It describes learning structures in terms of an information processing system involving long term memory, which effectively stores all of our knowledge and skills on a more-or-less permanent basis and working memory, which performs the intellectual tasks associated with consciousness. Information may only be stored in long term memory after first being attended to, and processed by, working memory. Working memory, however, is extremely limited in both capacity and duration. These limitations will, under some conditions, impede learning.
The fundamental tenet of cognitive load theory is that the quality of instructional design will be raised if greater consideration is given to the role and limitations, of working memory. Since its conception in the early 1980’s, cognitive load theory has been used to develop several instructional strategies which have been demonstrated empirically to be superior to those used conventionally.
Not all powerpoint is bad. For example showing a diagram and explaining its meaning is useful since it shows the same information in two different forms. These both reinforce each other.
I have never really liked powerpoints overfilled with text so now I have a reason to like them even less. The problem (as always?) lies in finding a good balance between visual aids that reinforce the message and distraction. But what really annoys me is my own dependence on powerpoint in my role as a teacher. In the long run I want to develop myself and leave technology behind.