This counter-intuitive finding has implications for anyone presenting the written word.
Students were given material to read printed in either a grey 12 point Comic Sans or Bodoni font and a 16 pony Arial font (Arial is considered one of the easiest to read).
They recalled 14% more facts from the document written in the harder to read font. In a semester long experiment students presented with slides and handouts with less legible typefaces performed better on tests than students presented with more legible typefaces.
Daniel Oppenheimer and his colleagues who carried out the research believe that easy-to-read typefaces enable you to skim the text without necessarily taking it in whereas harder-to-read text slows you down and makes you read more carefully. But you will also feel less confident as you read the difficult typeface so you will concentrate harder and process the information more deeply. These factors help to improve your recall.
However the implications are very interesting. To help people to retain information from text books you might have to print each chapter in a different font so readers don’t become acclimatised to one style. Using unfamiliar fonts like Monotype Corsiva, which is considered very hard-to-read might be a step too far but you could use different colours or contrasts or sizes which people can’t adjust to.
For all PowerPoint users who’ve been told to keep it simple and clear the message is that hard-to-read cluttered slides probably work better at assisting recall. Of course using a blackboard or flip chart (especially with my writing) should also improve recall.
There are a couple of provisos here. First you don’t want to make the material so hard to read that you frustrate people and they give up. Secondly the subjects in these experiments were all intelligent and motivated to learn. Thirdly if the reading were optional people wouldn’t necessarily have the motivation to finish reading.
Source: HBR March 2012