Speakers modulate their voice when talking to infants, but we know little about subtle variation in acoustic parameters during speech in adult social interactions. Because tests of perception of such variation are hampered by listeners' understanding of semantic content, studies often confine speech to enunciation of standard sentences, restricting ecological validity. Furthermore, apparent paralinguistic modulation in one language may be underpinned by specific parameters of that language. Here we circumvent these problems by recording speech directed to attractive or unattractive potential partners or competitors, and testing responses to these recordings by naive listeners, across both a Germanic (English) and a Slavic (Czech) language. Analysis of acoustic parameters indicates that men's voices varied F 0 most in speech towards potential attractive versus unattractive mates, while modulation of women's F 0 variability was more sensitive to competitors, with higher variability when those competitors were relatively attractive. There was striking similarity in patterns of social context-dependent F 0 variation across the two model languages, with both men's and women's voices varying most when responding to attractive individuals. Men's minimum pitch was lower when responding to attractive than unattractive women. For vocal modulation to be effective, however, it must be sufficiently detectable to promote proceptivity towards the speaker. We showed that speech directed towards attractive individuals was preferred by naive listeners of either language over speech by the same speaker to unattractive individuals, even when voices were stripped of several acoustic properties by low-pass filtering, which renders speech unintelligible. Our results suggest that modulating F 0 may be a critical parameter in human courtship, independently of semantic content.

During medical pandemics, protective behaviors need to be motivated by effective communication, where finding predictors of fear and perceived health is of critical importance. The varying trajectories of the COVID-19 pandemic in different countries afford the opportunity to assess the unique influence of ‘macro-level’ environmental factors and ‘micro-level’ psychological variables on both fear and perceived health. Here, we investigate predictors of fear and perceived health using machine learning as lockdown restrictions in response to the COVID-19 pandemic were introduced in Austria, Spain, Poland and Czech Republic. Over a seven-week period, 533 participants completed weekly self-report surveys which measured the target variables subjective fear of the virus and perceived health, in addition to potential predictive variables related to psychological factors, social factors, perceived vulnerability to disease (PVD), and economic circumstances. Viral spread, mortality and governmental responses were further included in the analysis as potential environmental predictors. Results revealed that our models could accurately predict fear of the virus (accounting for approximately 23% of the variance) using predictive factors such as worrying about shortages in food supplies and perceived vulnerability to disease (PVD), where interestingly, environmental factors such as spread of the virus and governmental restrictions did not contribute to this prediction. Furthermore, our results revealed that perceived health could be predicted using PVD, physical exercise, attachment anxiety and age as input features, albeit with smaller effect sizes. Taken together, our results emphasize the importance of ‘micro-level’ psychological factors, as opposed to ‘macro-level’ environmental factors, when predicting fear and perceived health, and offer a starting point for more extensive research on the influences of pathogen threat and governmental restrictions on the psychology of fear and health.

Our research consisted of two studies focusing on the probability of humans being able to perceive the difference between faces expressing pain versus pleasure. As controls, we included: smile, neutral facial expression, and expression of fear. The first study was online and was conducted using a large sample (n=902) of respondents. The second study was conducted in a laboratory setting and involved a stress induction procedure. For both, the task was to categorize whether the facial expression was rated positive, neutral or negative. Stimuli were faces extracted from freely downloadable online videos. Each rating participant (rater) was presented with five facial expressions (stimuli) of five females and five males. All raters were presented with the stimuli twice so as to evaluate the consistency of the ratings. Beforehand, we tested for stimuli differences using specialized software and found decisive differences. Using a Bayesian statistical approach, we could test for consistencies and due-to-chance probabilities. The results support the expectation that the results are not repeatable but indeed solely due to chance, diminishing the communication value of the expressions of pain and pleasure. The expression of fear was also rated due to chance, but not neutral and smile. Stress induction did have an impact on the perception of pleasure.

Introduction Research indicated that (i) vaginal orgasm consistency is associated with indices of psychological, intimate relationship, and physiological functioning, and (ii) masturbation is adversely associated with some such measures. Aim The aim of this study was to examine the association of various dyadic and masturbation behavior frequencies and percentage of female orgasms during these activities with: (i) measures of dyadic adjustment; (ii) sexual satisfaction; and (iii) compatibility perceived by both partners. Methods In a sample of 85 Czech long-term couples (aged 20–40; mean relationship length 5.4 years), both partners provided details of recent sexual behaviors and completed sexual satisfaction, Spanier dyadic adjustment, and Hurlbert sexual compatibility measures. Multiple regression analyses were used. Main Outcome Measure The association of sexual behaviors with dyadic adjustment, sexual compatibility, and satisfaction was analyzed. Results In multivariate analyses, women's dyadic adjustment is independently predicted by greater vaginal orgasm consistency and lower frequency of women's masturbation. For both sexes, sexual compatibility was independently predicted by higher frequency of penile–vaginal intercourse and greater vaginal orgasm consistency. Women's sexual satisfaction score was significantly predicted by greater vaginal orgasm consistency, frequency of partner genital stimulation, and negatively with masturbation. Men's sexual satisfaction score was significantly predicted by greater intercourse frequency and any vaginal orgasm of their female partners. Concordance of partner vaginal orgasm consistency estimates was associated with greater dyadic adjustment. Conclusions The findings suggest that specifically penile–vaginal intercourse frequency and vaginal orgasm consistency are associated with indices of greater intimate relationship adjustment, satisfaction, and compatibility of both partners, and that women's masturbation is independently inversely associated with measures of dyadic and personal function. Results are discussed in light of previous research and an evolutionary theory of vaginal orgasm.

Our research consisted of two studies focusing on the probability of humans being able to perceive the difference between valence of human vocalizations of high (pain, pleasure and fear) and low intensity (laugh and neutral speech). The first study was conducted online and used a large sample (n=902) of respondents. The second study was conducted in a laboratory setting and involved a stress induction procedure. For both, the task was to categorize whether the human vocalization was rated positive, neutral or negative. Stimuli were audio records extracted from freely downloadable online videos and can be considered semi-naturalistic. Each rating participant (rater) was presented with five audio records (stimuli) of five females and of five males. All raters were presented with the stimuli twice (so as to statistically estimate the consistency of the ratings). Using a Bayesian statistical approach, we could test for consistencies and due-to-chance probabilities. The outcomes support the prediction that the results (ratings) are repeatable (not due to chance) but incorrectly attributed, decreasing the communication value of the expressions of fear, pain, and pleasure. Stress induction (in study two conducted on 28 participants) did have an impact on the ratings of male neutral and laugh – it caused decrease in correct attribution.