Touching words is not enough: how visual experience influences haptic-auditory associations in the "Bouba-Kiki" effect.

Since Köhler's experiments in the 1920s, researchers have demonstrated a correspondence between words and shapes. Dubbed the "Bouba-Kiki" effect, these auditory-visual associations extend across cultures and are thought to be universal. More recently the effect has been shown in other modalities including taste, suggesting the effect is independent of vision. The study presented here tested the "Bouba-Kiki" effect in the auditory-haptic modalities, using 2D cut-outs and 3D models based on Köhler's original drawings. Presented with shapes they could feel but not see, sighted participants showed a robust "Bouba-Kiki" effect. However, in a sample of people with a range of visual impairments, from congenital total blindness to partial sight, the effect was significantly less pronounced. The findings suggest that, in the absence of a direct visual stimulus, visual imagery plays a role in crossmodal integration.