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.

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 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 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 of 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 prediction that the results are not repeatable but are solely due to chance, decreasing the communication value of the expressions of pain and pleasure. The expression of fear was also rated due to chance, but neither neutral nor smile. Stress induction did have an impact on the perception of pleasure.

Objectives: Research of sexuality often times includes individuals who choose to be researched and are willing to undergo the procedures. Samples of population (students and self-selected enthusiasts) may not resemble the nation’s population structure nor general idea of random human even though the psychological mechanisms researched are thought to be universal. The aim of this study was to investigate the relationship between proximal measures of domain specific and non-specific excitation and inhibition in two (probabilistic and non-probabilistic) samples. Sample and settings: We collected approximately 400 individuals from Central European country – Czech Republic – via specialized agency to match the probabilistic sample and a second similarly sized sample via snowball sampling and online advertisements at the same time. The participants were asked to fill in two questionnaires widely used by sex researchers (Sexual Inhibition and Excitation Scale and Sociosexual Orientation Inventory), and one scale designed to map broader motivations to avoid aversive outcomes and motivation to approach goal-oriented outcomes (Behavioral Inhibition and Activation Scale). Hypotheses: We expected partial or complete confirmation of previously found results (general and sexuality specific activation and inhibition and sociosexuality). We also expected that the replication will be affected by the sample choice. Statistical analyses: To follow methodologies of previous studies used to create hypotheses we decided to use partial correlation controlling for age of the participant. Results: Generally, the non-probabilistic sample findings resembled the published results whereas the probabilistic sample differed, especially in men. Furthermore, findings from women were the more consistent of the two sexes when comparing the probabilistic and non-probabilistic sample outcomes. Our results, relying on correlational analyses as majority of studies does, provide a valuable insight to impact of sampling on results. Limitations: The sample size, thus larger than usual studies, could be higher. We have been unable to research latent variables due to methodological constrains of the method - correlation.

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The emergence of altruistic behavior constitutes one of the most widely studied problems in evolutionary biology and behavioral science. Multiple explanations have been proposed, most importantly including kin selection, reciprocity, and costly signaling in sexual selection. In order to test the latter, this study investigated whether people behave more altruistically when primed by photographs of attractive faces and whether more or less altruistic people differ in the number of sexual and romantic partners. Participants in the general population (N = 158, 84 F, 74 M) first rated the attractiveness of photographs of 20 faces of the opposite (sexually preferred) sex and then played the Dictator and Ultimatum Games (DG and UG). The photograph rating acted as priming; half the participants received photographs of people rated as more attractive than average in an earlier study, and the other half received photographs previously rated as less attractive. The attractiveness-primed participants, especially men, were expected to behave more altruistically—signaling that they are desirable, resource-possessing partners. We also expected altruists to self-report more sexual and romantic partners. The observed difference between altruistic behaviors in the attractiveness- and unattractiveness-primed groups occurred in UG offers, however, in the opposite than expected direction in women. The number of sexual partners was positively correlated to minimum acceptable offers (MAOs) in the UG, in line with expectations based on the theory of costly signaling.