The Visual MythThe major reason used to justify bullet-point slides is that they help “visual” people. This is based on the theory of learning styles – that different people have different learning styles – visual, auditory and kinaesthetic. The theory suggests that some people are dominant in the visual mode and that bullet-point slides will help their learning. This conclusion is based on assuming that bullet-point slides are processed in the visual mode. This is a flawed assumption. Although the words on the screen enter the brain through the eyes ie: visually – they are processed in the verbal channel of the brain because they are words. This verbal channel is also trying to process the words being spoken by the presenter and so it gets overloaded.
This theory is backed up by research. Richard Mayer is an educational psychologist and researcher in multimedia learning. He designed an experiment to discover whether people learnt better when they both heard and read the same information, or when they just heard the information. One group of students simply listened to a spoken narration. The second group were saw identical text on the screen as well as the spoken narration. Both groups of students were then tested on their memory and understanding of the information.
Mayer found that the first group who simply listened to the spoken narration did significantly better than the students who also read the text on the screen. Their memory increased by 28%, and even more significantly, their understanding went up by 79%. So having text on the screen was harmful to the audience’s retention and understanding of the information (Richard Mayer, Multimedia Learning). Richard Mayer’s research was not directly based on PowerPoint but he’s said that this research is highly relevant to the design of PowerPoint presentations. In his words:
The implications are that: 1) PowerPoint presentations should use both visual and verbal forms of presentation, 2) filling the slides with information will easily overload people’s cognitive systems.