Source: Psychonomic Society (Barton & Halberstadt, Fig. 1)

There is a well-known set of studies in cognitive psychology on what is called the Kiki-Bouba effect. Say the word Kiki. Your mouth smiles when you say it. Now, say the word Bouba; you round your lips into an "O" when you say it. Research suggests that people prefer to match the word Kiki with angular shapes rather than rounded ones (as if the word sounds "angled") and to match the word Bouba with round shapes rather than angular ones.

Would this work for faces as well? Would rounded names feel better matched for rounded faces and angular names feel better matched for angular faces?

This question was addressed in a 2018 paper by David Barton and Jamin Halberstadt in the journal Psychonomic Bulletin and Review.

In the first two studies in this paper, participants saw either sketches or photos of faces that were selected to be either quite rounded or quite angular. They were then shown several names that could apply to these faces. Some of those names required rounding the mouth to say them (like Bob). Other names required more of a smile to say (like Kirk). Participants rank-ordered how well they thought the names matched the faces.

Consistent with the Kiki-Bouba effect, names requiring a rounded mouth were ranked on average as better for round faces than names requiring a smiling mouth. Names requiring a smiling mouth were ranked as better on average for angled faces than those requiring a rounded mouth. The effects were small but reliable in both studies.

Another study in this series randomly paired angled or round faces with names and asked people to judge how much they liked the person pictured. First, participants rated how much they liked each face, to control for the possibility that some kinds of faces are liked better than others. Then, they rated the face when paired with a name that either did or did not match the face. In this study, participants’ judgments of how much they liked a face went up when it was paired with a name that matched it, but didn’t change when it was paired with a name that didn’t match it.

People are not generally aware of the relationship between particular speech sounds and aspects of what they see. As a result, these small influences of the compatibility of a name with a face are things that can have an influence on the judgments of people without their awareness. That said, while this relationship between name and face shape was consistent across studies, it is important to emphasize that the effects are small. So, while this tells us something interesting about the relationship between sound and vision, it doesn’t really have much day-to-day impact on the way people treat each other.