On the development of relationships and bonding
Domestic and captive animals have a memory of individual human voices and of their association with emotional experiences
Playback experiments have shown that captive cheetahs, as well as domestic pigs and horses discriminate familiar human voices on the basis of past experiences (Coll. Univ. Bari, Italy, Witwatersrand, South Africa, Team 3 and INRA).
In pigs, we have demonstrated prenatal associations between human voices and the pregnant mother’s emotional experiences while hearing to these voices. Thus, 2 day-old experimental piglets (mother with voice playback during last month of pregnancy) were less distressed than control piglets (mother not submitted to playbacks during pregnancy) in isolation tests with playback of these same voices. They reacted more negatively when the voice associated with a negative emotional state of the pregnant mother was heard. This is a clear demonstration of transnatal memory and prenatal associative learning between sensory stimuli and maternal emotions. Since emotions may enhance attention, they may have triggered this process.
Vocal signals ensure coordination between partners
Intraspecific communication is of course a major a source of emotional responses. This is especially true in breeding processes where acoustic signals may be involved in ensuring synchrony between partners. In horses, we have found that the acoustic properties of stallions’ whinnies are predictive of their reproductive success. (Coll.Team 3). Synchrony between pair members can be important in a variety of situations beyond breeding: pale-winged starlings produce flight call sequences before flying off, but the probability of flying off depends on the joining up of the partner in calling and on increased temporal rhythms of the calls in the sequence, that potentially reflect an increase of arousal (Coll. Rhodes Univ., South Africa).
Social attention: a major feature in the evolution of vocal communication rules?
Temporal regulations of vocal interactions are also a core aspect of the so-called « turn-taking « rules of vocal exchanges. Well known in humans, it has been shown that in many animal species also, interlocutors leave space between successive calls/songs, leaving time for response. Comparative studies of Sturnids have revealed that territorial species, for which attention to the responses of neighbours may be crucial, favour discontinuous songs and turn taking rules whereas « family » groups favour communal singing and chorusing.
Vocal communication in social groups requires mutual intelligibility and information but also giving and receiving attention, a potential mediator of social bonding. In this respect, we argue that social attention could be a basis for the evolution of turn taking in many social species including humans (Coll. Team 3, IRP VOCOM).