Nodding in dis/agreement: a tale of two cultures.

Head movement is commonly used to communicate positive versus negative response. However, whereas in US culture, vertical head movement denotes positivity (nodding to say "yes") and horizontal head movement is associated with negativity (shaking heads to say "no"), in Bulgaria, this response pattern is reversed, that is, horizontal head movement means "yes" and vertical head movement means "no." Thus, these two cultures spatially "embody" agreement via different movement directions. We examined the effect of such cultural differences on cognitive processing that has no communicative intent by comparing ratings of likeability, brightness, and positive feeling associated with different color moving dots. Participants followed the dots' movement with their heads in a 2 (direction: vertical vs. horizontal) by 2 (speed: fast vs. slow) design. We found a two-way country by speed of movement interaction such that Bulgarian participants associated colors with more positive feeling when those were perceived in combination with slower head movement irrespective of movement direction. US participants, on the other hand, rated color dots as better mood-enhancing in combination with faster head movement. There was a similar two-way country by movement speed interaction for likeability ratings but none for brightness. Findings are discussed in terms of variability in gestural meaning and culture-specific embodiment patterns.