The specific aim of our study was to test individual common shrews from a population monitored long-term. In a preference test, we revealed sex-related differences in behavioral traits of young common shrews and consistent individual differences in sociability, boldness and in an exploration pattern that have not been reported previously. More active animals were bolder and more superficial in the exploration of non-social objects as compared to shier shrews. Significant inter-annual differences in sociability, boldness and exploratory activity were observed. When we assessed correlations of sociability with population density, non-residents\' abundance, activity shared in space, survivorship and home range size, we found a positive association with shared spatial activity and home range size. Contrary to expectation, sociability did not correlate with the density of residents and survivorship. A significant negative association of sociability with non-residents\' abundance was documented. Survivorship was associated only with an exploration pattern. The thoroughness of exploration positively correlated with non-residents\' abundance. We regard the inter-annual changes in sociability that we observed in the test as a by-product of survival of shrews with various exploration patterns that are associated with dispersal. We can hypothesize that the personality differences registered in this study are maintained by balancing frequency-dependent selection of animals that is associated with differences in habitat quality throughout the population cycle.

Psychotic patients with a lifetime history of cannabis use generally show better cognitive functioning than other psychotic patients. Some authors suggest that cannabis-using patients may have been less cognitively impaired and less socially withdrawn in their premorbid life. Using a dataset comprising 948 patients with first-episode psychosis (FEP) and 1313 population controls across 6 countries, we examined the extent to which IQ and both early academic (Academic Factor [AF]) and social adjustment (Social Factor [SF]) are related to the lifetime frequency of cannabis use in both patients and controls. We expected a higher IQ and a better premorbid social adjustment in psychotic patients who had ever used cannabis compared to patients without any history of use. We did not expect such differences in controls. In both patients and controls, IQ was 3 points higher among occasional-users than in never-users (mean difference [Mdiff] = 2.9, 95% CI = [1.2, 4.7]). Both cases and control daily-users had lower AF compared to occasional (Mdiff = -0.3, 95% CI = [-0.5; -0.2]) and never-users (Mdiff = -0.4, 95% CI = [-0.6; -0.2]). Finally, patient occasional (Mdiff = 0.3, 95% CI = [0.1; 0.5]) and daily-users (Mdiff = 0.4, 95% CI = [0.2; 0.6]) had better SF than their never-using counterparts. This difference was not present in controls (Fgroup*frequency(2, 2205) = 4.995, P = .007). Our findings suggest that the better premorbid social functioning of FEP with a history of cannabis use may have contributed to their likelihood to begin using cannabis, exposing them to its reported risk-increasing effects for Psychotic Disorders.

Given the reliance on self-report in studies of adults with intellectual disabilities, this study examined individual vs. parental reports concerning the social approach behaviors of adults with Williams syndrome (WS) across a hypothetical and a live behavioral setting. Individuals with WS (N = 30) were asked whether they would approach strangers in two hypothetical, laboratory tasks (yes/no questionnaire vs. judging facial stimuli of individuals with different emotional expressions). Similarly, their parents also responded to a rating scale of their child\'s social approach behavior toward strangers displaying various emotions. Then, in a community setting, behavioral coders recorded actual social approaches of individuals with WS toward strangers. Although self-report ratings were consistent across measures, these measures did not correspond to the individuals\' actual behaviors during the community observations. Conversely, parental reports did not correspond to their child\'s self-report measures, but parents did more accurately predict their child\'s real-life social approach behaviors. Implications are discussed for both research and practice.