Complement your speech with gestures if you want people to remember what you’re telling them, but make sure they’re related to what you’re saying and not just random gesticulations.
Pierre Feyereisen at the University of Louvain in Belgium showed 59 student participants a video of an actor uttering different sentences. Afterwards, he asked them to recall as many of the sentences as possible. He found they remembered more sentences that were accompanied by a meaningful gesture (e.g. “the buyer went round the property”, accompanied by the actor pointing his right index finger downwards and drawing a circle”) than sentences accompanied by a meaningless gesture (e.g. “He runs to the nearest house” accompanied by the actor holding his right hand open, palm facing upwards). A control condition with different students confirmed that without gestures, the sentences were all equally memorable.
The finding suggests it is the meaning inherent in gestures that acts as a memory aid, rather than the mere act of gesturing making some sentences more distinctive than others.
This was confirmed in a second experiment in which video editing was used to jumble up the actor’s utterances and gestures. When a meaningful gesture didn’t match the sentence it was combined with, it no longer acted as a memory aid. Again, this shows it isn’t the inherent physical complexity or appearance of meaningful gestures that underlies their mnemonic value, rather it is their representation of the sentence’s meaning that is important.
Feyereisen, P. (2006). Further investigation on the mnemonic effect of gestures: Their meaning matters. European Journal of Cognitive Psychology, 18, 185-205.