Neural activation to babyfaced men matches activation to babies

Abstract

Behavioral data supports the commonsense view that babies elicit different responses than adults do. Behavioral research also has supported the babyface overgeneralization hypothesis that the adaptive value of responding appropriately to babies produces a tendency for these responses to be overgeneralized to adults whose facial structure resembles babies. Here we show a neural substrate for responses to babies and babyface overgeneralization in the amygdala and the fusiform face area (FFA). Both regions showed greater percentage BOLD signal change compared with fixation when viewing faces of babies or babyfaced men than maturefaced men. Viewing the first two categories also yielded greater effective connectivity between the two regions. Facial qualities previously shown to elicit strong neural activation could not account for the effects. Babyfaced men were distinguished only by their resemblance to babies. The preparedness to respond to infantile facial qualities generalizes to babyfaced men in perceivers’ neural responses just as it does in their behavioral reactions.

Acknowledgements

This work was supported by NIH Grant MH066836 and NSF Grant 0315307 to the first and last authors and K02MH72603 to the first author. The Authors declare that they have no competing financial interests.

Notes

¹Exploratory analyses examining the effects of perceiver sex are reported in Appendix 2 rather than in the results section because we had no basis for making predictions. Previous research has found equivalent reactions to babyfaced vs. maturefaced adults by male and female perceivers (Berry & McArthur, 1985; Zebrowitz et al., 1993a, 2003), and there is mixed evidence concerning sex differences in response to babies. The most reliable effects are shown in public self-report data, with little consistency when physiological or behavioral responses toward infants are assessed (Berman, 1980). Also, the one study that examined brain activation found sex differences only when viewing faces of babies that were morphed to resemble the self, but not for other faces of babies (Platek et al., 2004).