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The modality principle1) claims that learning will be enhanced if presenting textual information in an auditory format, rather than in visual format, when it is accompanied with other visual information like a graph, diagram or animation.2)
The idea for this principle comes from Baddeley's working memory model in which information can be retrieved simultaneously through two channels: verbal and visual. Using both channels can therefore enhance learning since spoken text then occupies only verbal channel leaving visual channel free to process other visual information.
The modality principle suggests texts should be presented in audio format (in case it is accompanied with other visual information).
A recent meta-research has examined results of 43 studies and confirmed that3):