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Parity and Mortality : An Examination of Different Explanatory Mechanisms Using Data on Biological and Adoptive Parents


A growing literature has demonstrated a relationship between parity and mortality, but the explanation for that relationship remains unclear. This study aims to pick apart physiological and social explanations for the parity-mortality relationship by examining the mortality of parents who adopt children, but who have no biological children, in comparison with the mortality of parents with biological children. Using Swedish register data, we study post-reproductive mortality amongst women and men from cohorts born between 1915 and 1960, over ages 45-97. Our results show the relative risks of mortality for adoptive parents are always lower than those of parents with biological children. Mortality amongst adoptive parents is lower for those who adopt more than one child, while for parents with biological children we observe a U-shaped relationship, where parity-two parents have the lowest mortality. Our discussion considers the relative importance of physiological and social depletion effects, and selection processes.

Social consensus influences ethnic diversity preferences


There is widespread segregation between workplaces along ethnic lines. We expand upon previous research on segregation and social influence by testing the effect of the latter on personal diversity preferences, specifically in employees' selection into hypothetical workplaces. In a survey study with 364 European American respondents in three waves, participants complied with social consensus preferences for either more or less workplace diversity. The new preference was sufficiently internalized to be retained largely unaltered a week later. Simulations suggest a self-reinforcing effect, where accurate social consensus information may be sufficient to change preferences. Given that initial choices were polarized, perceived social consensus can vary highly between people in society, and influencing this perception may feed back into greater acceptance of minorities.

On the Role of Responses in Pavlovian Acquisition


A defining feature of Pavlovian conditioning is that the unconditioned stimulus (US) is delivered whether or not the animal performs a conditioned response (CR). This has lead to the question: Does CR performance play any role in conditioning? Between the 1930s and 1970s. a consensus emerged that CR acquisition is driven by CS-US (CS, conditioned stimulus) experiences, and that CRs play a minimal role, if any. Here we revisit the question and present 2 new quantitative methods to evaluate whether CRs influence the course of learning. Our results suggest that CRs play an important role in Pavlovian acquisition, in such paradigms as rabbit eye blink conditioning, pigeon autoshaped key pecking, and rat autoshaped lever pressing and magazine entry.

The nonsense math effect


Mathematics is a fundamental tool of research. Although potentially applicable in every discipline, the amount of training in mathematics that students typically receive varies greatly between different disciplines. In those disciplines where most researchers do not master mathematics, the use of mathematics may be held in too much awe. To demonstrate this I conducted an online experiment with 200 participants, all of which had experience of reading research reports and a postgraduate degree (in any subject). Participants were presented with the abstracts from two published papers (one in evolutionary anthropology and one in sociology). Based on these abstracts, participants were asked to judge the quality of the research. Either one or the other of the two abstracts was manipulated through the inclusion of an extra sentence taken from a completely unrelated paper and presenting an equation that made no sense in the context. The abstract that included the meaningless mathematics tended to be judged of higher quality. However, this nonsense math effect was not found among participants with degrees in mathematics, science, technology or medicine.

Weak support for a U-shaped pattern between societal gender equality and fertility when comparing societies across time



A number of recent theories in demography suggest a U-shaped relationship between gender equality and fertility. Fertility is theorized to be high in societies with low levels of gender equality, as well as in societies with high gender equality, with lower fertility in a transition phase.


This study estimates the relationship between gender equality (as operationalized through female political empowerment) and fertility within societies over time, using yearly information on gender equality and fertility for 35 countries.


When examining societies across time there is no evidence of a U-shaped relationship between gender equality and fertility. In cross-sectional analyses across countries for recent periods, such a U-shaped relationship can be observed. For within-society analyses a negative relationship is clear at lower levels of gender equality, while no pattern can be observed in societies with high gender equality.


Theories that fertility would increase following increasing gender equality are not supported for changes over time within countries. Implications and robustness of the findings are discussed.

What can associative learning do for planning?


There is a new associative learning paradox. The power of associative learning for producing flexible behaviour in non-human animals is downplayed or ignored by researchers in animal cognition, whereas artificial intelligence research shows that associative learning models can beat humans in chess. One phenomenon in which associative learning often is ruled out as an explanation for animal behaviour is flexible planning. However, planning studies have been criticized and questions have been raised regarding both methodological validity and interpretations of results. Due to the power of associative learning and the uncertainty of what causes planning behaviour in non-human animals, I explored what associative learning can do for planning. A previously published sequence learning model which combines Pavlovian and instrumental conditioning was used to simulate two planning studies, namely Mulcahy & Call 2006 'Apes save tools for future use.' Science 312, 1038-1040 and Kabadayi & Osvath 2017 'Ravens parallel great apes in flexible planning for tool-use and bartering. 'Science 357, 202-204. Simulations show that behaviour matching current definitions of flexible planning can emerge through associative learning. Through conditioned reinforcement, the learning model gives rise to planning behaviour by learning that a behaviour towards a current stimulus will produce high value food at a later stage; it can make decisions about future states not within current sensory scope. The simulations tracked key patterns both between and within studies. It is concluded that one cannot rule out that these studies of flexible planning in apes and corvids can be completely accounted for by associative learning. Future empirical studies of flexible planning in non-human animals can benefit from theoretical developments within artificial intelligence and animal learning.

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