We tend to pair round, blobby shapes with the sound bouba and spiky shapes with kiki. It’s the so-called bouba-kiki effect. Interestingly, this effect is common among adults who speak very different languages.

Various theories have been put forward. One holds that levels of emotional arousal may be key — that both kiki and a spiky shape trigger relatively high levels of arousal, compared with bouba and a blob. Now a new study, reported in Psychological Science, provides compelling evidence for this idea. The researchers also take their findings further, arguing that they could have important implications for understanding the early evolution of languages.

Apparently, a word will trigger different perceptions of arousal depending on its acoustic features.

“Any wordlike stimulus can potentially convey emotional information solely on the basis of its perceptual acoustic characteristics, making it possible to match it with emotionally similar concepts, eg. shapes,” the team writes.