Biology subjects

Clay, Z.

Publications and source records attributed to Clay, Z..

3 recordsLinked to original sources

bioRxiv2022

Categorization and discrimination of human and non-human primate affective vocalizations: investigation of the frontal cortex activity through fNIRS.

Many species, including humans and non-human primates, react differently to threatening or pleasant situations. Because of its adaptiveness, recognizing affective signals is likely to be reflected in a capability of modern humans to recognize other closely related species call content. However, at both behavioural and neural levels, only few studies have used a comparative approach to understand affective decoding processes in humans, particularly with respect to affective vocalizations. Previous research in neuroscience about the recognition of human affective vocalizations has shown the critical involvement of temporal and frontal regions. In particular, frontal regions have been reported as crucial in the explicit decoding of vocal emotions especially in different task complexity such as discrimination or categorization. The aim of this study using functional Near Infrared Spectroscopy (fNIRS) was to specifically investigate the neural activity of the inferior frontal cortex pars triangularis (IFGtri) and the prefrontal cortex (PFC) underlying categorization (A versus B) and discrimination (A versus non-A) mechanisms of positive and negative affects in human, great apes (chimpanzee and bonobo), and monkey (rhesus macaque) vocalizations. We also analysed participants behavioural responses and correlated them with the recorded frontal activations. While performing the tasks, fNIRS data revealed a clear distinction between the two frontal regions, with a general positive activation of IFGtri compared to a decrease of PFC activity. We also found a modulation of IFGtri and PFC activations depending on both the species considered and on task complexity; with generally more activity in the IFGtri during discrimination compared to categorization, and a more intense decrease of the PFC in categorization compared to discrimination. Behaviourally, participants recognized almost all affective cues in all species vocalizations at above chance levels in the discrimination task (except for threatening bonobo calls). For categorization, they mostly correctly identified at levels significantly above chance affective contents in human and great ape vocalizations but not in macaque calls. Overall, these findings support the hypothesis of a pre-human origin of affective recognition processing inherited from our common ancestor with other great apes and processed in the frontal cortex. Our results also highlight behavioural differences related to task complexity, i.e. between categorization and discrimination processes, and the differential involvement of the PFC and the IFGtri, which seems necessary to explicitly decode affects in all primate vocalizations.

neuroscience↗

bioRxiv2022

Humans recognize affective cues in primate vocalizations: Acoustic and phylogenetic perspectives

Humans are adept in extracting affective information from the vocalisations of not only humans but also other animals. Current research has mainly focused on phylogenetic proximity to explain such cross-species emotion recognition abilities. However, because research protocols are inconsistent across studies, it remains unclear whether human recognition of vocal affective cues of other species is due to cross-taxa similarities between acoustic parameters, the phylogenetic distances between species, or a combination of both. To address this, we first analysed acoustic variation in 96 affective vocalizations, including agonistic and affiliative contexts, of humans and three other primate species - rhesus macaques, chimpanzees and bonobos - the latter two being equally phylogenetically distant from humans. Using Mahalanobis distances, we found that chimpanzee vocalizations were acoustically closer to those of humans than to those of bonobos, confirming a potential derived vocal evolution in the bonobo lineage. Second, we investigated whether 68 human participants recognized the affective basis of vocalisations through tasks by asking them to categorize ( A vs B) or discriminate ( A vs non-A) vocalisations based on their affective content. Results showed that participants could reliably categorize and discriminate most of the affective vocal cues expressed by other primates, except threat calls by bonobos and macaques. Overall, participants showed greatest accuracy in detecting chimpanzee vocalizations; but not bonobo vocalizations, which provides support for both the phylogenetic proximity and acoustic similarity hypotheses. Our results highlight for the first time the importance of both phylogenetic and acoustic parameter level explanations in cross-species affective perception, drawing a more complex picture to explain our natural understanding of animal signals.

animal behavior and cognition↗

bioRxiv2022

Tactical signalling by victims increases bystander consolation in bonobos

Tactical emotion communication has long been considered uniquely-human. As a species, we readily exaggerate, inhibit and modify emotional expressions according to social context and audience. Notably, emitting emotional displays, such as those pertaining to distress states, can evoke empathic responses in others such as the offering of consolation to victims after a fight. Animal emotion expressions, by contrast, are traditionally viewed as uncontrollable arousal responses. Our study challenges this view by assessing the level of control in the emotional signalling of sanctuary-living bonobo victims following aggressive attacks (N = 27 victims, N = 144 attacks) and its and its corresponding effect on receivers. Results show that the production of paedomorphic signals by adult bonobo victims increased chances of receiving consolation from bystanders and reduced risk of future aggression from former opponents, highlighting a strategic function. Victim signalling also increased with audience size, yet strategies differed by age: immature bonobos were more likely to cease signalling in proximity of close-social partners, whereas adults were more likely to cease signalling after having been consoled. These data suggest that bonobo emotion communication has a developmental trajectory and that tactical emotion signalling is a Pan-human capacity, preceding the split of Homo.

animal behavior and cognition↗