Across many species, scream calls signal the affective significance of events to other agents.Scream calls were often supposed to be of generic alarming and fearful nature to signal potential threats including their instantaneous, involuntary, and accurate recognition by perceivers. However, scream calls are more diverse in their affective signaling nature than being limited to fearfully alarm a threat, and thus the broader sociobiological relevance of various scream types is unclear. Here we used four different psychoacoustic, perceptual decision-making, and neuroimaging experiments in humans to demonstrate, first, the existence of at least six generic and psycho-acoustically distinctive types of scream calls of both an alarming and a non-alarming nature, rather than being limited to only screams caused by fear or aggression. Second, based on perceptual and processing sensitivity measures for decision-making during scream recognition, we found that alarming screams (with some exceptions) were overall discriminated the worst, were responded to the slowest and were associated with the lower perceptual sensitivity for their recognition compared with non-alarm screams. Third, the neural processing of alarm compared with non-alarm screams during an implicit processing task elicited only minimal neural signal and connectivity in perceivers, contrary to the frequent assumption of a threat processing bias of the primate neural system. These findings show that scream calls are more diverse in their signaling and communicative nature in humans and that especially non-alarming screams, and positive screams in particular, seem to have higher efficiency in the cognitive, neural, and communicative processing in humans.
KEYWORDSVoice; affect; scream; auditory cortex; fMRI; neural network;Vocal affect bursts, such as crying, grunting, or laughing, are a major part of the sociobiological communication across many mammalian species, especially primates. A specific type of affect burst is a scream call. Screams are relatively short, loud and intense, high-pitched, tremulous, and rough voice calls [1][2][3]. They have a far-reaching impact [1,4] and seem to be immediately recognized by, adaptively and rapidly responded to, and hardly ignored by perceivers [5,6]. Screams are thus assumed to be an effective mode of communicating affect signals that are of high relevance in any sociobiological interaction [1]. Scream calls have a long evolutionary trajectory across many species up to human primates. In nonhuman primates [7-9] and other mammalian species [10], scream-like calls are frequently used as some specific type of alarm signal exclusively in negative contexts, such as in in-group social conflicts between rank different animals. Screams by lower ranking animals help to recruit support from allies [11,12], while higher ranking animals scream to intimidate the lower ranking [13]. Furthermore, "SOS screams" signal the presence of environmental threat (e.g. predators) [14,15]. Scream-like voice calls thus aim to trigger certain beha...