Emotions not only arise in reaction to an event but also while anticipating it, making this context a means of accessing the emotional value of events. Before now, anticipatory studies have rarely considered whether vocalisations carry information about emotional states. We studied both the grunts of piglets and their spatial behaviour as they anticipated two (pseudo)social events known to elicit positive emotions of different intensity: arrival of familiar conspecifics and arrival of a familiar human. Piglets spatially anticipated both pseudo-social contexts, and the spectro temporal features of grunts differed according to the emotional context. Piglets produced low-frequency grunts at a higher rate when anticipating conspecifics compared to anticipating a human. Spectral noise increased when piglets expected conspecifics, whereas the duration and frequency range increased when expecting a human. When the arrival of conspecifics was delayed, the grunt duration increased, whereas when the arrival of the human was delayed, the spectral parameters were comparable to those during isolation. This shows that vocal expressions in piglets during anticipation are specific to the expected reward. Vocal expressions—both their temporal and spectral features- are thus a good way to explore the emotional state of piglets during the anticipation of challenging events.

14Emotions not only arise in reaction to an eliciting event but also while anticipating it, making 15 this context a way to assess the emotional value of events. Anticipatory studies have poorly 16 considered vocalisations whereas they carry information about the emotional state. We studied 17 the grunts of piglets that anticipated two (pseudo)social events known to elicit positive emotions 18 more or less intense: arrival of a familiar conspecifics and arrival of a familiar human. Both 19 time and spectral features of the vocal expression of piglets differed according to the emotional 20 Manuscript -Submission 1 -piglets anticipation grunts context. Piglets produced low-frequency grunts at a higher rate when anticipating conspecifics 21 compared to human. Spectral noise increased when piglets expected conspecifics, whereas the 22 duration and frequency range increased when expecting a human. When the arrival of 23 conspecifics was delayed grunts duration increased, while when the arrival of the human was 24 delayed spectral parameters were comparable to those during isolation. This shows that vocal 25 expressions in piglets during anticipation are specific to the expected reward and to the time 26 duration between signal and the delivery of the reward. Vocal expression (time and spectral 27 features) is thus a good way to explore emotional state of piglets during anticipation of 28 challenging events. 29