| The associations of birth order with personality and intelligence in a representative sample of U.S. high school students Author links open overlay panelRodica IoanaDamianPersonEnvelopeBrent W.Roberts Show
ShareShare Cited ByCite https://doi.org/10.1016/j.jrp.2015.05.005Get rights and content AbstractWe tested birth order associations with personality traits and intelligence using Project Talent, a representative sample (N = 377,000) of U.S. high school students. Using a between-family design and several background factors (i.e., age, sex, sibship size, parental socio-economic status, and family structure), we were able to control for potential confounds, and estimate the links between birth order and outcomes across several different social categories. In addition to differences between firstborns and laterborns across the entire sample, we also tested birth rank trends in a sub-sample of targets from sibships of three, raised by two parents. Overall, the average absolute association between birth order and personality traits was .02, whereas the one between birth order and intelligence was .04. IntroductionBirth order is a human experience that is one of the most pervasive and universally thought to determine who we are (Sulloway, 1996). The debate over the association of birth order with personality and intelligence has spawned continuous interest over the past hundred years, both from the general public and from scientists. Books on birth order and why it matters for children’s personality, intelligence, development, and future success are among the top bestselling parenting books. And yet, among scientists, despite a consistent stream of research on birth order, results remain inconclusive and controversial. The present study uses the largest representative sample of U.S. students ever employed to help answer questions regarding the magnitude of associations between birth order, personality, and intelligence. Theories of the link between birth order and personality were at the core of one of the most heated scientific disputes of all time, between Sigmund Freud and Alfred Adler. To Freud’s outrage, Adler (a middle child himself) maintained that first- and lastborn children suffer from neuroses caused by their constant struggle for success and superiority, whereas middle children are healthier, easy going, and rebellious (Adler, 1928). Not surprisingly, Freud (a firstborn child himself) felt threatened by Adler’s idea, so the dispute ended in Adler’s resignation from the Psychoanalytic Society, and the minting of a new branch of psychology, the Society for Individual Psychology (Sulloway, 1999). In more recent times, as psychologists have moved away from psychoanalysis, questions about the link between birth order and personality have remained popular, but the dominant theoretical model is currently derived from evolutionary theory. According to evolutionary models, siblings compete for maximum parental investment (Trivers, 1985) and develop strategies to increase parental attention by filling different “niches” within the family (Sulloway, 1996). Thus, the firstborn fills the more “traditional” niche, by being a responsible, dominating role-model, who worries about parent-pleasing (i.e., the firstborn should be higher in Conscientiousness, intellectual aspects of Openness, the dominance aspect of Extraversion, and Neuroticism), whereas the laterborn fills the more “rebellious” niche, by being more original, easy going, and sociable (i.e., the laterborn should be higher in the unconventional aspects of Openness, Agreeableness, and the sociability aspect of Extraversion). In addition to being linked to personality, birth order has also been linked to intelligence, though this theoretical model has a distinct history. The idea that birth order might be related to intelligence started with Sir Francis Galton (1874) who found that firstborn sons were over-represented among prominent English scientists. He attributed this finding to primogeniture practices, whereby 19th century English families invested more resources in firstborn sons (both in terms of attention, nourishment, as well as financial resources and education). He also proposed an explanation based on family environmental influence, whereby firstborns are given more responsibilities than their younger siblings, which might help their intellectual development. Modern theory has maintained the idea that firstborns might show higher levels of intelligence because of the family environment in which they are raised. Thus, the confluence model (Zajonc, 2001, Zajonc and Markus, 1975) has proposed that the ordinal position of each child in the family determines the level of intellectual stimulation available in early years and thus, their later intelligence. The basic tenet is that the more adults and the fewer children are present in the home, the richer is the overall intellectual environment. Furthermore, with each (younger) child that is added to the family, the overall intellectual environment becomes diluted. Therefore, the level of intellectual stimulation is purportedly lower for laterborns because the parents have less undivided attention to offer them and the overall intellectual environment of the home is depressed. Though theories based on family environmental influences, such as the confluence model, are by far the most influential, some theories have claimed that the link between birth order and intelligence is explained by prenatal or gestational factors. Specifically, Gualtieri and Hicks (1985) have proposed that maternal antibody levels increase with each subsequent pregnancy which might affect the fetal brain and thus lead to lower intelligence levels among laterborns. We will revisit this issue later, when we present past empirical data. In studying the links between birth, personality, and intelligence, there are two major methodological issues that have contributed to the continuing debate over inconsistent findings present in the literature. First is the issue of confounding variables, which, if not properly taken into account, can produce biased estimates of the effects. Second is the issue of design choice, that is, whether a birth order study uses a between- versus a within-family design. We discuss both of these issues below. Previous research and theory (e.g., Sulloway, 1996) suggests that the most important potential confounds in birth order research are sibship size, parental socio-economic status (SES), family structure, age, and gender. If not properly accounted for, these factors may lead to biased estimates of the links between birth order, personality, and intelligence (Ernst and Angst, 1983, Rodgers et al., 2000). The most recurring “offender” among the above confounds, across research on birth order and personality, as well as research on birth order and intelligence, is sibship size (Ernst and Angst, 1983, Rodgers et al., 2000). Sibship size represents the total number of siblings present in a family. This is an important confound for research on birth order, because firstborns (versus lastborns) are more likely to be “found” in low sibships (e.g., the probability of finding a firstborn child from a sibship of two is .50, whereas the probability of finding a firstborn child from a sibship of five is .20). Furthermore, sibship size might influence family dynamics, which might in turn result in distinct patterns of sibling competition and personality development (Dixon, Reyes, Leppert, & Pappas, 2008). Sibship size may also influence intelligence levels, because, according to the confluence model, families with more children exist in a diluted intellectual environment, which may negatively affect intellectual development (Zajonc, 2001). Additionally, researchers (Rodgers et al., 2000) have proposed that sibship size is related to parental intelligence because parents with higher levels of intelligence tend to have fewer children. This implies that any study that finds higher levels of intelligence among firstborns without controlling for sibship size may simply be showing that intelligence is heritable. Finally, sibship size is also highly correlated to parental SES (i.e., wealthier, more educated parents tend to have fewer children), which brings us to the next confound. Parental SES is a composite score derived from the level of education, income, and occupational prestige attained by the parents. Parental SES is an important confound in birth order because firstborns tend to come disproportionately from higher SES families, due the lower sibship sizes present in these families (Ernst and Angst, 1983, Rodgers et al., 2000). Furthermore, Previous research has shown that parents of higher SES tend to have higher levels of intelligence and tend to be higher in personality trait levels that might have helped them become successful in the first place (e.g., high conscientiousness, high dominance extraversion) (Shanahan, Bauldry, Roberts, Macmillan, & Russo, 2014). Thus, higher SES parents may pass on to their children higher levels of intelligence and certain personality traits through both genetic and environmental mechanisms independent of birth order (Shanahan et al., 2014), but because firstborns are over-represented among higher SES families, in the absence of parental SES controls, it may appear as if firstborns were higher in intelligence, conscientiousness, dominance, and so on due to their birth rank. Another confound that’s been highly debated in the context of birth order and personality research is family structure, which classifies families into families with two parents, parent and step-parent, single parent, adoptive parents, no parents, and so on. Children who are raised in stable homes by two parents should provide a cleaner test of birth order associations, because other types of family structure might introduce various confounds; for example, in blended families, where younger siblings are the genetic offspring of both parents, but older half-siblings are not, the younger siblings are likely to receive higher-quality parental investment and thus be more likely to act as firstborns (Sulloway, 1996). Age is another possible confound of the associations between birth order and personality, because associations are expected to be larger in childhood and adolescence (Sulloway, 2010). As mentioned earlier, according to Sulloway, birth order effects on personality arise from sibling competition. This competition necessarily happens within the family context and it is likely at its peak during childhood and adolescence when the siblings are most dependent on resources from their parents, and thus must strive to capture their attention and favors through carving their own personality “niche.” However, as children grow up and become increasingly independent, it is possible that birth order effects decrease because the roles that were once relevant for survival in the family context in early years may no longer be relevant once the child leaves the family environment (Harris, 2000, Harris, 2006). Finally, some researchers (e.g., Sampson & Hancock, 1967) have argued that gender is another potential confound of the association between birth order and personality, because male and female firstborn children may have different levels of susceptibility to parental influence. Specifically, the researchers argued that firstborn males might be more susceptible to parental influence and to filling the more “traditional” niche by being a responsible, dominating role-model. This increase susceptibility of male firstborns might be due to social norms which have historically imposed a lot of family responsibility on the shoulders of the firstborn son as the one to take over the role of future head of the family in paternalistic societies. In sum, any serious attempt at establishing the link between birth order, personality, and intelligence should take into account the following background factors: sibship size, parental socio-economic status (SES), family structure, age, and gender. As mentioned earlier, another major source of controversy in the birth order literature (both with respect to personality and intelligence) is the type of design one chooses to employ (i.e., a between- versus a within-family design). A between-family study design assesses the personality and intelligence of a cross-section of unrelated people. Additionally, when the participants are individually surveyed, they also report their birth rank (e.g., do they have older siblings or not). Then the researcher compares the scores of first- and laterborns across families, because the participants are not related. In contrast, a within-family design assesses the personality and intelligence of siblings within the same family and then compares the first and laterborn scores of siblings from the same family. Both between- and within-family designs are widely used and they both have advantages and disadvantages, which we detail below. Between-family designs have been criticized primarily for not being able to adequately control for between-family differences in sibship size, parental socio-economic status (SES), family structure, age, gender, genetic differences, and specific family practices (Paulhus, Trapnell, & Chen, 1999). For the reasons discussed in the previous section, ignoring these sources of variance is likely to produce biased estimates of the birth order effects. The second criticism brought to between-family designs is that they do not reflect the within-family dynamics put forward by the evolutionary niche-finding model, whereby each child is trying to find a niche that has not yet been filled, in order to receive maximum investment from the parents (Sulloway, 1999). Regarding within-family designs of birth order, some researchers have claimed they are superior to between-family designs because they can adequately control for confounding factors (i.e., researchers assume that if siblings come from the same family, that means they were raised with the same level of parental SES, family structure, etc.) and because they reflect the within-family dynamics put forward by the evolutionary model (Paulhus et al., 1999). However, other researchers have brought strong criticism to this idea for several reasons. First, within-family designs, as they are currently used, tend to introduce a perfect age confound (Wichman, Rodgers, & MacCallum, 2006). Specifically, studies so far have tested all siblings at the same time, which means the firstborn was always older than the laterborns at the time of assessment. Given what we know about personality development and maturation (Hogan & Roberts, 2004) it is very possible that the firstborn only appears to be more conscientious, for example, due to being older.1 The second criticism brought to within-family studies of birth order and personality is that they may suffer from demand effects or social stereotypes that may inflate the correlations (Michalski & Shackelford, 2001). This problem is enhanced, according to Marini and Kurtz (2011), by the fact that the existing within-family research on birth order and personality is limited by its use of a single rater from each family. Specifically, the single rater compares oneself against one’s siblings, thus increasing the likelihood of perceiving a contrast. To our knowledge, there is only one study currently available that used a within-family design (Bleske-Rechek & Kelley, 2014), where each sibling rated their personality independently. The latter study found very small associations with birth order, and these associations were smaller compared to those found in within-family studies that used a single rater, thus supporting the demand effects hypothesis. This demand effect problem does not apply, however, to birth order and intelligence research, where siblings fill in their own intelligence tests. It becomes apparent that neither between-, nor within-family designs are ideal for studying the effects of birth order. However, there is some potential for improvement. First, the confound issue of between-family designs (Paulhus et al., 1999), may be addressed by using large representative samples, along with statistical controls for parental SES, sibship size, and family structure (Black et al., 2011). Presumably, statistical controls are much more effective and produce more accurate estimates when samples are larger and more representative, because selection biases are minimized, and because control variables (e.g., parental SES) are normally distributed and include the full range of possibilities. Second, between-family designs that include large representative samples and a broad range of control variables may also address some of the issues present in within-family designs. For example, between-family designs would pose no age confound because all the participants could be the same age and measured at the same time and/or age can be a control variable. Furthermore, between-family designs using independent assessments of each participant would also not suffer from demand effects due to social stereotypes (which could occur when one person rates themselves in relation to their sibling). Finally, although Sulloway (1999) has posited that between-family designs may not represent well enough the within-family dynamics put forward by the evolutionary model, between-family designs do reflect quite accurately the way in which birth order effects have been interpreted and broadcast by both researchers (e.g., Sulloway, 1996) and the popular media (e.g., Leman, 2009). Specifically, birth order researchers (e.g., Sulloway, 1996) have proposed that people’s personalities develop a certain way as a result of within-family dynamics (i.e., sibling competition and “niche-finding”). This implies that behavioral patterns resulted from sibling competition are not expected to be transitory and confined to the rearing environment, but they are expected to be internalized and be an important part of people’s personality development. In other words, due to behavioral patterns that people need to resort to within the family, personalities may develop in a way that makes, for instance, firstborns more conscientious and lastborns more agreeable. If that is the case, then birth order effects should also appear across families. Early studies of birth order and personality (e.g., Forer, 1977) used between-family designs, small samples, and no control variables for sibship size, parental SES, or family structure. In 1983, Ernst and Angst published a detailed review of the literature dating from 1946 to 1980, concluding that birth order effects on personality had been grossly overestimated due to the use of between-family designs without proper controls for the above confounding factors. In 1996, Sulloway revived the idea that birth order may influence personality by publishing his seminal book, Born to Rebel, where he proposed the evolutionary account for birth order effects, whereby siblings compete for resources and try to fill in distinct family “niches.” In this book, the maximum absolute correlations were estimated to be .40 for Openness, .35 for Conscientiousness, .30 for Agreeableness, .20 for Neuroticism, and .10 for Extraversion (see Sulloway, 1996, p. 473, Note 76). At that time, the author also proposed that within-family studies might produce larger effects than between-family studies, because between-family studies might not be able to properly account for confounding factors even when statistically controlling for these factors, and because between-family designs might not fully reflect within-family dynamics.2 A follow-up within-family study conducted on 6053 individuals found that the absolute correlations were .08 for Openness, .18 for Conscientiousness, .10 for Agreeableness, .04 for Neuroticism, and .14 for Extraversion (Sulloway, 1999).3 Furthermore, between-family studies estimated absolute partial correlations between birth order and personality to be about one-third to one-half of the effect size found in within-family studies (Sulloway, 2007, Sulloway, 2010), which translates as follows: Openness (r = .04–.06), Conscientiousness (r = .06–.09), Agreeableness (r = .03–.05), Neuroticism (r = .02–.03), and Extraversion (r = .04–.07). Since then, research on birth order and personality has produced a continuous stream of conflicting results, where some studies found support to the predictions derived from the evolutionarily based family “niche” model (e.g., Saroglou & Fiasse, 2003), whereas others have not (e.g., Marini and Kurtz, 2011, Michalski and Shackelford, 2001). Research on birth order and intelligence followed a similar pattern to research on birth order and personality, although thanks to larger sample sizes, the findings tend to be more consistent, albeit no less controversial (Zajonc & Sulloway, 2007). The classic study by Belmont and Marolla (1973) was conducted on the entire population of Dutch 19-year-old males and found that intelligence declined steadily from firstborns to lastborns even when controlling for sibship size and parental SES. Although these findings, along with others (e.g., Zajonc, 1976), supported Zajonc’s (2001) “confluence model” of intelligence, these studies have been criticized for using between-family designs, which were purportedly unable to properly account for confounding factors (Rodgers, 2000, Rodgers et al., 2000). Researchers (e.g. Rodgers et al., 2000, Wichman et al., 2006) using within-family designs found no significant relationship between birth order and intelligence. However, more recent studies, conducted on large representative samples of the Norwegian population, found birth order effects on intelligence, with laterborn children showing lower IQs than their early-born counterparts, in both between- and within-family designs (Bjerkedal et al., 2007, Black et al., 2011). Further analyses of the representative Norwegian sample (Kristensen & Bjerkedal, 2007) showed that the likely mechanism behind these effects is the family interaction and stimulation (the confluence model), rather than prenatal gestational factors. The authors brought support for the family interaction model (as opposed to the biological model) by showing that secondborns, who were raised as firstborns because their older sibling had died, had higher levels of intelligence than children who were secondborn biologically and were raised as such because their older sibling had survived. In sum, over the past two decades, estimates of the effects of birth order on personality have shifted dramatically, in some instances tenfold, studies estimating effects to range from a correlation of .40 to null effects (Marini and Kurtz, 2011, Sulloway, 1996). Some of these changes could be attributed to differences in study design (within- versus between-family) or confounding factors. However, another possibility is that the use of underpowered study designs is at fault. Large representative samples would be useful for establishing reliable estimates of the effects of birth order on personality, especially in the context of between-family studies, where effects are expected to be smaller. To be precise, an adequately powered between-family study, would need to include a sample of 15,455, to detect an r = .02 with 80% power at p < .05. In the absence of such large data sets, the hypotheses put forward by evolutionary models cannot be reliably tested and we are left wondering what effects birth order really has on personality. Regarding the link between birth order and intelligence, the results are much more consistent across different designs, possibly due to the very large representative samples employed (e.g., the Norwegian data included a quarter of a million participants). Furthermore, research on birth order and intelligence consistently supports the family interaction model (e.g., the confluence model). The present study has three major advantages over previous studies: (a) its large representative sample of U.S. high school students, which allows for a confident estimation of effect sizes; (b) the availability of several background measures (age, sex, sibship size, parental SES, and family structure) and the availability of large samples within each background category, which allows for systematic tests of the associations between birth order, personality, and intelligence across different background factors, and (c) its focus on both personality and intelligence in the same sample, which allows for effect size comparisons. The large sample size renders standard inferential statistics relatively uninformative as almost every effect is statistically significant in the overall sample (e.g., r = .01 are statistically significant in the 6-digit sample). Moreover, even a focus on confidence intervals (Cumming, 2013) is not useful because the intervals are so narrow that any effect that differs by the magnitude of .01 on the r metric would be different from any other effect. We therefore describe the effects in terms of whether they are in the direction expected and the magnitude of the correlation or partial correlation for interpretive purposes. Based on Sulloway, 1996, Sulloway, 2001, Sulloway, 2007, Sulloway, 2010, we predicted that firstborns (versus laterborns) should be higher in Conscientiousness, Neuroticism, and the dominance aspect of Extraversion, whereas laterborns should be higher in Agreeableness and the sociability aspect of Extraversion.4 Based on Zajonc’s confluence model (2001), we predicted that firstborns (versus laterborns) should score higher on intelligence measures, and that the association should become stronger with increasing distance between birth ranks. The absolute value of the effect size (r) between two neighboring birth ranks is expected to be between .02 and .04 (Zajonc & Sulloway, 2007). Regarding how the associations of birth order and personality traits and intelligence might change across different demographic and family background categories, we did not have clear predictions, because this is the first study to systematically test the birth order associations across different background categories. Section snippetsParticipantsThe data come from Project Talent (see Wise, McLaughlin, & Steel, 1979), a longitudinal study that started in 1960 with 5% of America’s high-school students. Over 440,000 students in grades 9 through 12 participated, of which 377,016 cases are now available, which make up one of the largest representative samples of students currently available. In the present study, we used data from the original survey to test the roles of birth order and family background on personality and intelligence. ResultsTable 1 contains descriptive statistics and inter-correlations among all the variables of interest. As expected, sibship size correlated negatively with parental SES, which made firstborns overrepresented among low sibship or high SES families. Two-parent households were also characterized by lower sibship sizes and higher SES. Of all the background factors, the largest absolute raw correlations with personality and intelligence were found for parental SES (ranging from .09 to .44), followed by DiscussionWe investigated the nature and magnitude of the link between birth order and personality, and between birth order and intelligence. Past research on birth order and personality found contradictory evidence, ranging from null effects to a pattern of differences where firstborns are higher in conscientiousness, neuroticism, and dominance, whereas laterborns are higher in agreeableness and sociability (Sulloway, 1996). Past research on birth order and intelligence generally found a benefit for ConclusionThis study helps establish reliable effect size estimates for birth order on self-report data of personality and on intelligence, taking into account several background factors, in a large representative sample of U.S. high school students. In a between-family design, we found very small associations between birth order and personality, with an average absolute partial correlation of .02. The partial correlations between birth order and cognitive abilities were slightly higher, the average AcknowledgementsThis research uses data from Project Talent, a project directed by the American Institutes of Research (AIR). Information on how to obtain the Project Talent data files is available on the AIR website (http://www.air.org/) and from Susan Lapham (). This research was supported by a grant from NIA (R01 AG21178, Roberts, PI). References (46)
The new statistics: Why and howPsychological Science(2013) Can personality traits and intelligence compensate for background disadvantage? Predicting status attainment in adulthoodJournal of Personality and Social Psychology(2014) Birth order: Its influence on personality(1983) The birth order factor(1977) Indicators of socioeconomic positionJournal of Epidemiology and Community Health(2006) English men of science(1874) An immunoreactive theory of selective male afflictionBehavioral and Brain Sciences(1985) Context-specific learning, personality, and birth orderCurrent Directions in Psychological Science(2000) No two alike: Human nature and human individuality(2006) A socioanalytic model of maturityJournal of Career Assessment(2004) The Big Five inventory(1991) Adopted children and stepchildren: 2010Adoption Quarterly(2010) Explaining the relation between birth order and intelligenceScience(2007) 2023, Personality and Individual Differences Show abstractNavigate Down Sulloway's ‘born to rebel’ hypothesis posits that later-borns develop personality characteristics which diverge from the status quo. Considering inconsistencies in the birth order literature as well as theoretical and methodological criticisms levied against this theory, we tested predictions derived from it using a sample of N = 2011 participants from the UK and Poland. We predicted later-borns would more likely have tattoos, and that this would be mediated by openness, risk-taking, sensation-seeking, and need for uniqueness. Tattooed individuals had higher risk-taking, sensation-seeking, and need for uniqueness, but birth order was not a predictor of having tattoos. Furthermore, although later-borns had higher risk-taking and sensation-seeking, they had lower need for uniqueness. Our results do not provide support for the ‘born to rebel’ hypothesis. 2022, British Accounting Review Show abstractNavigate Down Our study examines whether CEOs’ birth order can predict firms’ credit ratings. Consistent with studies that document a positive relationship in the general population between being firstborn and being conservative, our study finds that firms managed by firstborn CEOs tend to have higher credit ratings than those managed by later-born CEOs. Our results are robust to controlling for additional personal CEO traits, such as political identity, and to using a propensity score matching sample. A change analysis supports the causality of the firstborn effect. We suggest that return on assets and free cash flow are possible channels through which firstborn status affects credit ratings. Cross-sectional analyses show that the positive association is less (more) pronounced for firstborn CEOs who have a pilot license (run firms in less competitive industries). These results suggest that managerial conservatism may be an important factor in credit rating agencies’ credit risk assessments. 2021, Journal of Business Research Show abstractNavigate Down Individuals’ birth order may be a fundamental, engrained human early-life and family-domain experience that shapes their behaviors in adulthood. However, limited knowledge is available about the influence of birth order on individual innovation preferences. By integrating sibling rivalry theory and social identity theory and analyzing 186 high-technology entrepreneurial firms, we find that founder birth order is positively associated with product innovation generation (later-born founders pursue more innovation generation than do earlier-born founders) but is negatively associated with product innovation adoption (earlier-born founders generate more innovation adoption than do later-born founders). Further, both the age spacing between a founder and closest-born sibling and founder social identity moderate the relationships. Thus, our findings advance understanding in the literature on birth order and on entrepreneurial innovation. Blessed are the first: The long-term effect of birth order on trust2020, Economics and Human Biology Show abstractNavigate Down Acknowledging childhood as a crucial period for the formation of social preferences, we investigate whether the order of birth predicts trust in adult life. We find that laterborns trust on average 5% less than their older siblings, independently from personality traits, family ties, risk aversion and parental inputs. Family random- and fixed-effects estimates suggest that the variation in trust is mostly explained by within- rather than between-family characteristics. The effect of birth order is mediated by education outcomes only for women, while it is moderated by mother’s education for the entire sample, thereby leading to relevant policy implications. Birth order revelations about managers2022, Management Research Review No Evidence that Siblings' Gender Affects Personality Across Nine Countries2022, SSRN Research article Biosensors and Bioelectronics, Volume 192, 2021, Article 113506 Show abstractNavigate Down An increasing number of reports substantiate the link between emerging estrogenic pollutants and a variety of adverse effects including developmental disorders, infertility, cancer and neurological disorders, threatening public health as well as environment. The detection of the diverse classes of estrogenic and antiestrogenic substances is still challenging due to analytics which needs to cover the whole range of compounds acting on estrogen receptors and the complex estrogen pathways. In this proof-of-concept study, we report a novel biomimetic detection scheme based on the specific recognition of estrogenic ligands by estrogen sulfotransferase 1E1 (SULT1E1), which acts as one of the key enzymes in estrogen homeostasis. SULT1E1 was site-specifically immobilized on transparent glass slides via a hexahistidine-tag in a multi-step procedure. Soft colloidal probes (SCPs) covalently functionalized with ligands of SULT1E1, namely estrone and estradiol 17-(β-D-glucuronide), served as adhesion probes. The various functionalization steps were analyzed and optimized using epifluorescence, confocal laser scanning as well as reflection interference contrast microscopy (RICM). A competitive SCP binding assay probing the elastic SCP deformation driven by the specific interaction between SCPs and the SULT1E1 decorated glass slides was employed in conjunction with an optical readout by RICM and automated image analysis to detect estrogenic compounds by their inhibition of SCP adhesion. This sensing concept has demonstrated exceptional specificity for estrogenic steroid compounds compared to structurally related substance classes and provides promising options for multiplexed assays and incorporation of other proteins of the endocrine system to fully capture the whole ensemble of hormonally active substances. Research article Behavioural Brain Research, Volume 370, 2019, Article 111968 Show abstractNavigate Down The C-terminal domain of the heavy chain of tetanus toxin (Hc-TeTx) may be of therapeutic potential in motor impairments associated with Parkinson disease (PD). Since depression is a common co-morbid condition with PD, we undertook this study to determine whether Hc-TeTx might also show antidepressant-like properties and whether central brain-derived neurotrophic factor (BDNF) and/or tumor necrosis factor (TNF)-alpha are also affected by it. Adult male Wistar-Kyoto rats, a putative animal model of depression, were treated with various doses of Hc-TeTx (0, 20, 40 and 60 μg/kg, IM) and their performance in the open field locomotor activity (OFLA) as well as in the forced swim test (FST) was evaluated at 24 h, one week and two weeks after the single injection. A separate group of rats were injected with 60 μg/kg Hc-TeTx and sacrificed 24 h later for neurochemical evaluations. Hc-TeTx resulted in a dose-dependent decrease in immobility score after 24 h, whereas OFLA was not affected. Concomitant with the 24 h behavioral effects, the levels of hippocampal and frontal cortical BDNF were significantly increased, whereas the levels of TNF-alpha in both these areas were significantly decreased. The decrease in immobility scores following higher doses of Hc-TeTx were still evident after one week, but not 2 weeks of rest. These results indicate long lasting antidepressant effects of a single Hc-TeTx dose and suggest potential utility of Hc-TeTx in PD-depression co-morbidity. Research article Computers in Human Behavior, Volume 107, 2020, Article 106262 Show abstractNavigate Down This study sought to understand the effects of moderating uncivil online comments on the people who do this task. Results from an experiment (N = 747) show that moderating only uncivil comments made moderators less accurate at that task, more emotionally exhausted, and more dissatisfied with the task, relative to moderating only civil comments or a mix of civil and uncivil comments. In addition, results show evidence of a mediation effect. Specifically, moderating all uncivil comments made people more emotionally exhausted, and this exhaustion in turn led people to be less accurate in picking which comments to reject or accept for publication on a news site comment thread. However, moderating comments had no effect on perceptions of flow, an immersive experience, conceptually borne out of the field of positive psychology. Results suggest breaking up strenuous online labor tasks, such as comment moderation, and alternating comment moderation with other types of work to reduce the deleterious effects of the task. Research article Journal of Experimental Social Psychology, Volume 76, 2018, pp. 249-258 Show abstractNavigate Down Although it appears to be a common social behavior, very little is known about the nature of bullshitting (i.e., communicating with little to no regard for evidence, established knowledge, or truth; Frankfurt, 1986) and the social conditions under which it is most likely to occur. The current investigation examines specific antecedents of bullshitting, particularly examining topic knowledge, evidence for or against an obligation to provide an opinion hypothesis, and an ease of passing bullshit hypothesis. Experiment 1 suggests that bullshitting is augmented only when both the social expectations to have an opinion, and the cues to show concern for evidence, are weak. Experiment 2 demonstrates that bullshitting can also be attenuated under conditions of social accountability. Results are discussed in light of social perception, attitude change, and new directions aimed at reducing the unwanted effects of bullshitting. Research article Toxicon, Volume 187, 2020, pp. 279-284 Show abstractNavigate Down A survey on 5115 beekeepers and 121 patients treated with bee venom by an apitherapy clinic in the Hubei province, the epicenter of COVID-19 in China, reported that none of the beekeepers developed symptoms associated with COVID-19, the new and devastating pandemic. The hypothesis that immunity to bee venom could have a preventive effect was expressed and the authors of the Chinese survey suggested that the next step should be animal experiments on monkeys. We believed that before starting such studies, a second independent survey should verify the findings and define the hypothesis more clearly. Thus we asked all German beekeepers to complete an assessment form which would summarize their experiences with COVID-19. In contrast to the Chinese study we found that two beekeepers had died from a SARS-CoV-2 infection and forty-five were affected. The reaction to bee stings (none; mild swelling; severe swelling) correlated with the perceived severity of the SARS-CoV-2-infection-associated symptoms - exhaustion and sore throat. Beekeepers comorbidity correlated with problems with breathing at rest, fever, and diarrhea. Our results did not confirm the findings of the Chinese study. However, since the antiviral effects of bee venom have been found in several studies, we cannot exclude that there could be a direct preventive or alleviating effect when bee venom is administered during the infection. Research article Psychoneuroendocrinology, Volume 113, 2020, Article 104552 Show abstractNavigate Down Testosterone is associated with status-seeking behaviors such as competition, which may depend on whether one wins or loses status, but also on the stability of one’s status. We examined (1) to what extent testosterone administration affects competition behavior in repeated social contests in men with high or low rank, and (2), whether this relationship is moderated by hierarchy stability, as predicted by the status instability hypothesis. Using a real effort-based design in healthy male participants (N = 173 males), we first found that testosterone (vs. placebo) increased motivation to compete for status, but only in individuals with an unstable low status. A second part of the experiment, tailored to directly compare stable with unstable hierarchies, indicated that exogenous testosterone again increased competitive motivation in individuals with a low unstable status, but decreased competition behavior in men with low stable status. Additionally, exogenous testosterone increased motivation in those with a stable high status. Further analysis suggested that these effects were moderated by individuals’ trait dominance, and genetic differences assessed by the androgen receptor (CAG-repeat) and dopamine transporter (DAT1) polymorphisms. Our study provides evidence that testosterone specifically boosts status-related motivation when there is an opportunity to improve one’s social status. The findings contribute to our understanding of testosterone’s causal role in status-seeking motivation in competition behavior, and indicate that testosterone adaptively increases our drive for high status in a context-dependent manner. We discuss potential neurobiological pathways through which testosterone may attain these effects on behavior. |
At which age is the debate of personality stability versus change most heated
zusammenhängende Posts
Urheberrechte © © 2024 berikutyang Inc.
