Comparative EEG reveals general and conspecific vocalization sensitivities in evolutionarily distant mammal species

Mammal brains are tuned to vocal sounds. This tuning is reflected by at least two component processes: general and conspecific vocalization sensitivities. Using non-invasive electrophysiology, we directly compared the temporal characteristics of these sensitivities in three phylogenetically distant mammal species: humans (N = 20), dogs (N = 38) and pigs (N = 11). Event-related potentials (ERPs) were recorded while participants listened to human, dog, pig, and non-vocal sounds. On frontal electrodes, humans and pigs exhibited general vocalization sensitivity: differential ERPs for any vocalizations versus non-vocal sounds, already in early time windows (humans: 162-378 and 534-726 ms, pigs: 72-540 ms), indicating vocalizations' greater perceived saliency. Conspecific vocalization sensitivity, i.e. ERP differences between conspecific vocalizations and any other sounds were identified in all three species, in later time windows (humans: 468-552 and 572-640 ms, dogs: 314-506 ms; pigs: 254-436 ms), perhaps reflecting categorical processing. These findings reveal that general and conspecific vocalization sensitivities are served by evolutionarily conserved, temporally and functionally distinct neural mechanisms.