A Recursive Partitioning Method for the Prediction of Preference Rankings Based Upon Kemeny Distances

Preference rankings usually depend on the characteristics of both the individuals judging a set of objects and the objects being judged. This topic has been handled in the literature with log-linear representations of the generalized Bradley-Terry model and, recently, with distance-based tree models for rankings. A limitation of these approaches is that they only work with full rankings or with a pre-specified pattern governing the presence of ties, and/or they are based on quite strict distributional assumptions. To overcome these limitations, we propose a new prediction tree method for ranking data that is totally distribution-free. It combines Kemeny’s axiomatic approach to define a unique distance between rankings with the CART approach to find a stable prediction tree. Furthermore, our method is not limited by any particular design of the pattern of ties. The method is evaluated in an extensive full-factorial Monte Carlo study with a new simulation design.     

A mathematical model of the evolution of individual differences in developmental plasticity arising through parental bet‐hedging

Children vary in the extent to which their development is shaped by particular experiences (e.g. maltreatment, social support). This variation raises a question: Is there no single level of plasticity that maximizes biological fitness? One influential hypothesis states that when different levels of plasticity are optimal in different environmental states and the environment fluctuates unpredictably, natural selection may favor parents producing offspring with varying levels of plasticity. The current article presents a mathematical model assessing the logic of this hypothesis – specifically, it examines what conditions are required for natural selection to favor parents to bet‐hedge by varying their offspring's plasticity. Consistent with existing theory from biology, results show that between‐individual variation in plasticity cannot evolve when the environment only varies across space. If, however, the environment varies across time, selection can favor differential plasticity, provided fitness effects are large (i.e. variation in individuals’ plasticity is correlated with substantial variation in fitness). Our model also generates a novel restriction: Differential plasticity only evolves when the cost of being mismatched to the environment exceeds the benefits of being well matched. Based on mechanistic considerations, we argue that bet‐hedging by varying offspring plasticity, if it were to evolve, would be more likely instantiated via epigenetic mechanisms (e.g. pre‐ or postnatal developmental programming) than genetic ones (e.g. mating with genetically diverse partners). Our model suggests novel avenues for testing the bet‐hedging hypothesis of differential plasticity, including empirical predictions and relevant measures. We also discuss several ways in which future work might extend our model.     

Increased conspiracy beliefs among ethnic and Muslim minorities

In the present study, we tested whether Muslim minority members are more susceptible to conspiracy theories than majority members in the Netherlands. We examined conspiracy theories that are relevant (portraying the Muslim community as victim or Jewish people as perpetrators) and irrelevant for participants' Muslim identity (about the 2007 financial crisis, and other theories such as that the moon landings were fake). Results revealed that Muslims believed both identity‐relevant and irrelevant conspiracy theories more strongly than non‐Muslims. These differences could not be attributed to the contents of Muslim faith: Ethnic minority status exerted similar effects independent of Muslim identity. Instead, evidence suggested that feelings of both personal and group‐based deprivation independently contribute to belief in conspiracy theories. We conclude that feelings of deprivation lead marginalized minority members to perceive the social and political system as rigged, stimulating belief in both identity‐relevant and irrelevant conspiracy theories.     

The Mandate of the Ecumenical Movement

This is the text of the address given by Willem A. Visser 't Hooft to the Uppsala Assembly of the World Council of Churches (WCC) in 1968 after being named honorary president of the WCC, following his retirement as general secretary two years earlier. In this address, Visser 't Hooft reviews the 20th‐century history of the ecumenical movement and the contemporary mandate of the WCC, in which the central issue is the relationship between the church and the world, where the vertical dimension to God of the church's unity determines the horizontal dimension of its service to the world. The address concludes with four challenges: no horizontal advance without vertical orientation; the ecumenical movement and the churches need each other; church unity is important; and youth expects answers.     

The impact of premature childbirth on parental bonding

The development of an affectionate parent-infant bond is essential for a newborn infant's survival and development. However, from evolutionary theory it can be derived that parental bonding is not an automatic process, but dependent on infants' cues to reproductive potential and parents' access to resources. The purpose of the present study was to examine the process of bonding in a sample of Dutch mothers (n = 200) and fathers (n = 193) of full-term (n = 69), moderately premature (n = 68), and very premature infants (n = 63). During the first month postpartum parents completed the Pictorial Representation of Attachment Measure (PRAM) and Postpartum Bonding Questionnaire (PBQ). Longitudinal analyses revealed that mothers' PRAM scores decreased after moderately preterm delivery, whereas decreases in PRAM scores occurred in both parents after very preterm delivery. As lower PRAM scores represent stronger feelings of parent-infant connectedness, our findings suggest a higher degree of bonding after premature childbirth. Results of the PBQ analysis were in line with PRAM outcomes, as parents of preterm infants reported less bonding problems compared to parents of full-terms. These findings support the hypothesis that in affluent countries with adequate resources, bonding in parents of preterm infants on average may be higher than in parents of full-term infants.     

Affective regulation of cognitive-control adjustments in remitted depressive patients after acute tryptophan depletion

Negative affect in healthy populations regulates the appraisal of demanding situations, which tunes subsequent effort mobilization and adjustments in cognitive control. In the present study, we hypothesized that dysphoria in depressed individuals similarly modulates this adaptation, possibly through a neural mechanism involving serotonergic regulation. We tested the effect of dysphoria induced by acute tryptophan depletion (ATD) in remitted depressed patients on conflict adaptation in a Simon task. ATD temporarily lowers the availability of the serotonin precursor L-Tryptophan and is known to increase depressive symptoms in approximately half of remitted depressed participants. We found that depressive symptoms induced by ATD were associated with increased conflict adaptation. Our finding extends recent observations implying an important role of affect in regulating conflict-driven cognitive control.     

Redundant sensory information does not enhance sequence learning in the serial reaction time task

In daily life we encounter multiple sources of sensory information at any given moment. Unknown is whether such sensory redundancy in some way affects implicit learning of a sequence of events. In the current paper we explored this issue in a serial reaction time task. Our results indicate that redundant sensory information does not enhance sequence learning when all sensory information is presented at the same location (responding to the position and/or color of the stimuli; Experiment 1), even when the distinct sensory sources provide more or less similar baseline response latencies (responding to the shape and/or color of the stimuli; Experiment 2). These findings support the claim that sequence learning does not (necessarily) benefit from sensory redundancy. Moreover, transfer was observed between various sets of stimuli, indicating that learning was predominantly response-based.