Cognitive Control of Distinct Vocalizations in Rhesus Monkeys

Abstract

Whether nonhuman primates can decouple their innate vocalizations from accompanied levels of arousal or specific events in the environment to achieve cognitive control over their vocal utterances has been a matter of debate for decades. We show that rhesus monkeys can be trained to elicit different call types on command in response to arbitrary visual cues. Furthermore, we report that a monkey learned to switch between two distinct call types from trial to trial in response to different visual cues. A controlled behavioral protocol and data analysis based on signal detection theory showed that noncognitive factors as a cause for the monkeys' vocalizations could be excluded. Our findings also suggest that monkeys also have rudimentary control over acoustic call parameters. These findings indicate that monkeys are able to volitionally initiate their vocal production and, therefore, are able to instrumentalize their vocal behavior to perform a behavioral task successfully.

Single neurons in monkey prefrontal cortex encode volitional initiation of vocalizations

“…Further, we show that the distribution of the start frequency of the calls shows no significant differences between the two call groups. Small, yet significant differences were found for call duration (Po0.01, Wilcoxon-ranked sum test) and peak frequency (Po0.01, Wilcoxon rank sum test), as it has been shown previously 20 (Fig. 6f).…”

“…Cognitive control of non-human primate vocalizations, however, would be required to demonstrate that monkeys can be trained to reliably vocalize in response to arbitrary (that is, non-hedonic and non-social) cues in a controlled experimental protocol. In a recent study, we demonstrated that monkeys can be trained to reliably call in response to arbitrary visual stimuli 20 . Macaques thus show the minimum requirement for volitional instrumentalization of their vocalizations.…”

Limiting parental feedback disrupts vocal development in marmoset monkeys

“…Second is the more elaborate ability to decouple calls of the monkeys' innate vocal repertoire from the accompanying motivational state for use in a novel context2930. For example, instrumentalizing their vocal output to perform a specific task successfully in operant conditioning tasks51525354. In both types of vocal usage learning, vocal output does not have to depend on vocal imitation.…”

Nonlinguistic vocalizations from online amateur videos for emotion research: A validated corpus

“…It is found in all mammals and triggers species-specific emotional vocalizations. The basic acoustic structure of such vocalizations is predetermined by the pattern-generating neurons in medullary reticular formation and cannot be modified voluntarily (Hage, Gavrilov, & Nieder, 2013;U. Jürgens, 2009).…”