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Latest 2020 Publication 


Effect of racial bias on composite construction

by Kavya Bhardwaj, Graham Hole

“We investigated how prior bias about a face’s racial characteristics can affect its encoding and resultant facial composite construction. In total, 61 participants (24 Europeans, 18 Indians living in India and 19 Indians living in Europe) saw a racially ambiguous unfamiliar face and were led to believe it was either European or Indian. They created a composite of this face, using EFIT6. Two groups of independent raters (one Indian, the other European) then assessed the apparent race of each composite. A different two groups (one Indian, one European) assessed each composite’s degree of resemblance to the target face, to determine whether this was influenced by the constructors’ initial categorisation of the target face as “own‐race” or “other‐race.” Composites appeared significantly more “Asian” or “European” according to the bias induced in their creators, but there was no evidence of any own‐race bias in the resemblance ratings for the composites.”


Women’s voice pitch lowers after pregnancy 


by Katarzyna Pisanski, Kavya Bhardwaj, David Reby 


Women’s voice pitch (the perceptual correlate of fundamental frequency, F0) varies across the menstrual cycle and lowers after menopause, and may represent a putative signal of women’s fertility and reproductive age. Yet, despite dramatic changes in women’s sex hormone levels and bodies during and after pregnancy, previous between-subject and case studies have not found systematic changes in F0 due to pregnancy. Here, we tracked within-individual variation in 20 mothers’ voices during their first pregnancy, as well as up to 5 years before conception and 5 years postpartum. Voice recordings from 20 age-matched nulliparous women were measured as a control. Linear Mixed Models indicated that F0 mean, range and variation changed significantly following pregnancy in mothers, controlling for age at time of recording, whereas we did not observe any F0 changes across corresponding timeframes in our sample of nulliparous controls. Mothers’ voices became significantly lower-pitched and more monotonous during the first year postpartum compared to during pregnancy or before. These F0 parameters did not decrease within-individuals over a 5-year period prior to conception above and beyond the effects of ageing. Although voice pitch decreased following pregnancy, mothers’ F0 parameters reverted after the first year postpartum, approaching pre-pregnancy levels. Our results demonstrate that pregnancy has a transient and perceptually salient masculinizing effect on women’s voices.”

Pisanski, K., Bhardwaj, K., & Reby, D. (2018). Women’s voice pitch lowers after pregnancy. Evolution and Human Behavior39(4), 457-463.