Perceiving humanness across ages: neural correlates and behavioral patterns

Toshiki Saito; Rui Nouchi; Ryo Ishibashi; Kosuke Motoki; Yutaka Matsuzaki; Akiko Kobayashi; Motoaki Sugiura; Ryuta Kawashima

doi:10.3389/fpsyg.2024.1361588

Perceiving humanness across ages: neural correlates and behavioral patterns

Front Psychol. 2024 Apr 4:15:1361588. doi: 10.3389/fpsyg.2024.1361588. eCollection 2024.

Authors

Toshiki Saito^{1

2

3}, Rui Nouchi^{1

4}, Ryo Ishibashi^{1

4

5}, Kosuke Motoki^{1

6}, Yutaka Matsuzaki¹, Akiko Kobayashi^{1

3

7}, Motoaki Sugiura^{1

8}, Ryuta Kawashima¹

Affiliations

¹ Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan.
² Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
³ Japan Society for the Promotion of Science, Tokyo, Japan.
⁴ Smart Ageing Research Center, Tohoku University, Sendai, Japan.
⁵ National Institute of Information and Communications Technology, Osaka, Japan.
⁶ Department of Management, The University of Tokyo, Tokyo, Japan.
⁷ School of Economics and Management, Kochi University of Technology, Kochi, Japan.
⁸ International Research Institute of Disaster Science, Tohoku University, Sendai, Japan.

Abstract

Humanness perception, which attributes fundamental and unique human characteristics to other objects or people, has significant consequences for people's interactions. Notably, the failure to perceive humanness in older adults can lead to prejudice. This study investigates the effect of a target's age on humanness perception in terms of two dimensions: agency (the ability to act and do) and experience (the ability to feel and sense). We also examined brain activity using a magnetic resonance imaging (MRI) scanner in order to understand the underlying neural mechanisms. Healthy university students viewed the facial images of older and younger individuals and judged the humanness of each individual in terms of agency and experience while inside the MRI scanner. The results indicated that older adults were rated higher on experience, and no difference was found in ratings for agency between younger and older face images. Analysis of brain imaging data indicated that positive functional connectivity between the ventral and dorsal regions of the medial prefrontal cortex (mPFC) was greater when judging the humanness of younger faces than older faces. We also found that the negative functional connectivity between the left inferior frontal gyrus and postcentral gyrus was greater when judging the humanness of older faces as compared to that of younger faces. Although the current study did not show distinct brain activities related to humanness perception, it suggests the possibility that different brain connectivities are related to humanness perception regarding targets belonging to different age groups.

Keywords: dehumanization; fMRI; functional connectivity; humanness perception; older adults.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This work was supported by JSPS KAKENHI [Grant numbers 1073068, 19J12925, and 21J01224] and a Research Grant from the Division for Interdisciplinary Advanced Research and Education, Tohoku University.