The CANDOR corpus: Insights from a large multimodal dataset of naturalistic conversation.

People spend a substantial portion of their lives engaged in conversation, and yet, our scientific understanding of conversation is still in its infancy. Here, we introduce a large, novel, and multimodal corpus of 1656 conversations recorded in spoken English. This 7+ million word, 850-hour corpus totals more than 1 terabyte of audio, video, and transcripts, with moment-to-moment measures of vocal, facial, and semantic expression, together with an extensive survey of speakers' postconversation reflections. By taking advantage of the considerable scope of the corpus, we explore many examples of how this large-scale public dataset may catalyze future research, particularly across disciplinary boundaries, as scholars from a variety of fields appear increasingly interested in the study of conversation.

Acoustic regularities in infant-directed speech and song across cultures.

When interacting with infants, humans often alter their speech and song in ways thought to support communication. Theories of human child-rearing, informed by data on vocal signalling across species, predict that such alterations should appear globally. Here, we show acoustic differences between infant-directed and adult-directed vocalizations across cultures. We collected 1,615 recordings of infant- and adult-directed speech and song produced by 410 people in 21 urban, rural and small-scale societies. Infant-directedness was reliably classified from acoustic features only, with acoustic profiles of infant-directedness differing across language and music but in consistent fashions. We then studied listener sensitivity to these acoustic features. We played the recordings to 51,065 people from 187 countries, recruited via an English-language website, who guessed whether each vocalization was infant-directed. Their intuitions were more accurate than chance, predictable in part by common sets of acoustic features and robust to the effects of linguistic relatedness between vocalizer and listener. These findings inform hypotheses of the psychological functions and evolution of human communication.

Evidence on the nature of sectarian animosity from a geographically representative survey of Iraqi and Iranian Shia pilgrims.

Sectarian tensions underlie conflicts across the Middle East, but little is known about their roots and associated beliefs. We conducted a large-scale empirical analysis, drawing on an original, geographically representative survey of over 4,000 devout Shiites across Iran and Iraq. We find that sectarian animosity is linked to economic deprivation, political disillusionment, lack of out-group contact and a sect-based view of domestic politics-paralleling patterns seen in ethno-nationalism elsewhere. In contrast, two alternative accounts are largely unsupported: sectarian animosity is not consistently associated with solidarity with a transnational sect-based community, nor does it seem to stem from disputes over religious doctrine. Nonetheless, this identity's religious roots manifest in differences from typical ethno-nationalism; practising men are less sectarian, consistent with official doctrine encouraging unity, whereas practising women are more sectarian. These gendered patterns suggest an understudied mechanism: religiously mediated socialization, or the transmission of non-religious norms through religious practice.

Revealing racial bias.

Causal inference can make sense of imperfect policing data.

The role of officer race and gender in police-civilian interactions in Chicago.

Diversification is a widely proposed policing reform, but its impact is difficult to assess. We used records of millions of daily patrol assignments, determined through fixed rules and preassigned rotations that mitigate self-selection, to compare the average behavior of officers of different demographic profiles working in comparable conditions. Relative to white officers, Black and Hispanic officers make far fewer stops and arrests, and they use force less often, especially against Black civilians. These effects are largest in majority-Black areas of Chicago and stem from reduced focus on enforcing low-level offenses, with greatest impact on Black civilians. Female officers also use less force than males, a result that holds within all racial groups. These results suggest that diversity reforms can improve police treatment of minority communities.

Universality and diversity in human song.

What is universal about music, and what varies? We built a corpus of ethnographic text on musical behavior from a representative sample of the world's societies, as well as a discography of audio recordings. The ethnographic corpus reveals that music (including songs with words) appears in every society observed; that music varies along three dimensions (formality, arousal, religiosity), more within societies than across them; and that music is associated with certain behavioral contexts such as infant care, healing, dance, and love. The discography-analyzed through machine summaries, amateur and expert listener ratings, and manual transcriptions-reveals that acoustic features of songs predict their primary behavioral context; that tonality is widespread, perhaps universal; that music varies in rhythmic and melodic complexity; and that elements of melodies and rhythms found worldwide follow power laws.