Neuroscience & Psychology Postgraduate Society Seminars

Culture shapes interbrain synchronization during human goal decoding

Human societies are built on people accomplishing balanced individualistic and collectivistic goals to enhance their survival. Culture impacts upon human interactions and plays a critical role in regulating social goals. Western societies are individualistic, promoting values of independence, individual goals and rights. On the contrary, Eastern societies are collectivistic, promoting values of interdependence, group goals and duties. This marked social contrast was asserted as being responsible for consistent behavioural perceptual biases observed across cultures. However, whether culture has the potency to modulate natural human goal decoding in the brain has never been directly investigated. To this end, we used fMRI to record BOLD signals of Western and Eastern observers while they were viewing two natural movies featuring individualistic (i.e. eating alone) or collectivistic actions (i.e. a group building a house) in an African tribe. Movies were thus controlled for visual familiarity, culture and eye movements, which were locked to a central fixation. Inter-subject cortical synchronization was calculated by iteratively correlating the whole BOLD signal time course across all pairs of subjects, independently per voxel, movie type and cultural group. The resulting maps were normalised. Then, a BOLD collectivistic and individualist index was calculated, thresholded for each voxel by using bootstrap confidence intervals and averaged across movie type. Crucially, Western observers showed more synchronous activity in the occipital cortex during the decoding of human individualistic activities. The superior parietal lobe is involved in mapping internal representations of both the world and one's own body, and was found synchronously activated in Easterners during the decoding of the collectivist movies. Our data show culture-specific neural tunings for natural human individualistic and collectivistic goal decoding. These findings have profound implications in the understanding of social interactions and challenge the view that decoding of the visual world is universally achieved across human beings.