Multisensory vocal communication in primates and the evolution of rhythmic speech

The integration of the visual and auditory modalities during human speech perception is the default mode of speech processing. That is, visual speech perception is not a capacity that is “piggybacked” on to auditory-only speech perception. Visual information from the mouth and other parts of the face is used by all perceivers to enhance auditory speech. This integration is ubiquitous and automatic and is similar across all individuals across all cultures. The two modalities seem to be integrated even at the earliest stages of human cognitive development. If multisensory speech is the default mode of perception, then this should be reflected in the evolution of vocal communication. The purpose of this review is to describe the data that reveal that human speech is not uniquely multisensory. In fact, the default mode of communication is multisensory in nonhuman primates as well but perhaps emerging with a different developmental trajectory. Speech production, however, exhibits a unique bimodal rhythmic structure in that both the acoustic output and the movements of the mouth are rhythmic and tightly correlated. This structure is absent in most monkey vocalizations. One hypothesis is that the bimodal speech rhythm may have evolved through the rhythmic facial expressions of ancestral primates, as indicated by mounting comparative evidence focusing on the lip-smacking gesture

Eye Gaze and Head Posture Jointly Influence Judgments of Dominance, Physical Strength, and Anger

Social status hierarchies are a universal principle of organization in human societies. Status judgments are often influenced by perceptions of the face and posture. Two important nonverbal cues of social status are head postures and eye gaze. Prior research has shown contradictory results and little is known about the interaction of these two cues. Study 1 investigated how eye gaze (direct vs. averted) and head postures (bowed vs. neutral vs. raised) impact judgments of dominance and physical strength. Judgments of dominance were influenced more than judgments of physical strength. Furthermore, raised heads implied dominance and strength, but in contrast to common assumptions, a bowed head conveyed dominance if the eyes gazed at the observer. Study 2 showed that bowed heads with direct gaze conveyed anger, potentially explaining the increased judgments of dominance. Taken together, the results show that head posture and gaze interactively modulated status-related traits and emotions, namely, dominance, strength, and anger, and help clarify prior incompatible findings on head postures and eye gaze. This is a pre-print of an article published in Journal of Nonverbal Behavior. The final authenticated version is available online at: https://doi.org/10.1007/s10919-018-0276-

Happiness and Joy

Happiness and joy involve feelings of positive engagement which are prototypically expressed through the face, voice, and body. Joyful smiles tend to be strong and involve both eye constriction (the Duchenne marker) and mouth opening. Through approximately 2 months of age, joyful expressions are primarily rooted in physiological arousal. Positive emotional expressions then quickly become more social, occurring in face-to-face interactions with caregivers as infants increasingly derive psychological meaning from individuals and events. Beginning in the second half of the first year of life, infants’ expressions of positive emotion are increasingly incorporated into patterns of intentional communication. Between 1 and 2 years of age, positive expressivity is increasingly responsive to parental affective cues during pretense play. Preschoolers’ between 2 and 5 years of age utilize specific forms of positive emotion expressions to foster affiliation with their peers. By 8 years of age, children voluntarily control their expressions of positive emotion depending on the interpersonal context. These early expressions of joy are associated with later social competence, including reduced behavioral inhibition and reticence in reaction to novelty, compliance with parental requests, tolerance of new experiences, and attachment security. Further, positive expressivity is also linked to later life outcomes, primarily life satisfaction and overall well-being in adulthood. Positive emotion expression varies as a function of gender as well as cultural differences in the emotional significance and perceptions of positive expressions. Finally, the development of joyful expressivity is differentially sensitive to a variety of risk conditions, including maternal depression, prematurity, infant blindness, Down syndrome, and autism spectrum disorder