The Newxin puzzle

A variety of thought experiments suggest that, if the standard picture of practical rationality is correct, then practical rationality is sometimes an obstacle to practical success. For some, this in turn suggests that there is something wrong with the standard picture. In particular, it has been argued that we should revise the standard picture so that practical rationality and practical success emerge as more closely connected than the current picture allows. In this paper, I construct a choice situation—which I refer to as the Newxin puzzle—and discuss its implications in relation to the revisionist approach just described. Using the Newxin puzzle, I argue that the approach leads to a more radically revisionist picture of practical rationality than current debate suggests.

Optimal Partitioning of a Data Set Based on the p-Median Model

Although the K-means algorithm for minimizing the within-cluster sums of squared deviations from cluster centroids is perhaps the most common method for applied cluster analyses, a variety of other criteria are available. The p-median model is an especially well-studied clustering problem that requires the selection of p objects to serve as cluster centers. The objective is to choose the cluster centers such that the sum of the Euclidean distances (or some other dissimilarity measure) of objects assigned to each center is minimized. Using 12 data sets from the literature, we demonstrate that a three-stage procedure consisting of a greedy heuristic, Lagrangian relaxation, and a branch-and-bound algorithm can produce globally optimal solutions for p-median problems of nontrivial size (several hundred objects, five or more variables, and up to 10 clusters). We also report the results of an application of the p-median model to an empirical data set from the telecommunications industry.     

School outcomes of a community-wide intervention model aimed at preventing problem behavior

The Early Intervention for Children at Risk for Developing Behavioral Problems (EICR) is a community-wide intervention model preventing and treating problem behavior and promoting social competence in children. The aim of the study was to test whether EICR would result in fewer incidences of problem behavior and improved learning climate in elementary schools in a Norwegian municipality. The municipality was divided in two, each section having equal chance of being assigned to the intervention condition. Participants were principals and school staff. One year after the initiation of EICR, the prevalence of student problem behavior was significantly lower, and student relations were significantly better for schools located in the intervention area than for schools located in the comparison area. The findings support further development, implementation and research on the EICR model.     

家庭功能对青少年情绪问题的作用机制

本研究以探索家庭功能发挥过程和发挥结果之间的关系并检验两者对青少年情绪问题的作用大小和机制为目的,采用Skinner等人编制的家庭评价量表(FAM,测量家庭功能发挥过程)和Olson编制的家庭适应性、亲密度量表(FACESⅢ,测量家庭功能发挥结果)、流调中心抑郁量表(CES-D)和焦虑自评量表(SAS)对422名中学生进行匿名问卷施测,通过相关分析、分层回归和结构方程模型统计分析发现:(1)总体上青少年的情绪处于良好状态;(2)家庭功能发挥过程和发挥结果各变量之间呈显著相关;(3)家庭功能发挥过程比家庭功能发挥结果对青少年情绪问题预测作用更大;(4)家庭功能发挥结果是家庭功能发挥过程与青少年情绪问题的部分中介变量。     

合作学习小组的认知风格对其问题解决的影响

本研究以认知风格为依据,将合作学习小组分为场依存同质组、场独立同质组及异质组,通过小组对开放问题以及逻辑问题的解决,考察不同认知风格个体、不同类型小组的问题解决水平。结果表明:(1)个体认知风格的作用依任务性质不同而不同。(2)异质组中存在的个体之间的差异会成为有效沟通合作的障碍,进而影响异质组的问题解决水平,影响程度受到问题本身对沟通合作要求程度的影响。(3)异质分组能更好解决开放性问题。     

2～11岁儿童问题行为的稳定性与变化

本研究采用追踪研究方法,考察了儿童2岁、4岁、7岁、11岁时内隐问题行为和外显问题行为的稳定性和变化。结果发现,各个年龄阶段,父母报告的问题行为都具有中等程度的相关。儿童的问题行为2岁时最多,此后开始下降,11岁时问题行为最少。儿童的问题行为具有中等程度的连续性,2岁、4岁、7岁、11岁的问题行为之间的相关均非常显著。     

Evidence of means–end behavior in Asian elephants (<Emphasis Type="Italic">Elephas maximus</Emphasis>)

The present study explores to what extent Asian elephants show “means–end” behavior. We used captive Asian elephants (N = 2) to conduct four variations of the Piagetian “support” problem, which involves a goal object that is out of reach, but rests on a support within reach. In the first condition, elephants were simultaneously presented with two identical trays serving as the “support”, with the bait on one tray and the other tray left empty. In the next two conditions, the bait was placed on one tray, while additional bait was placed beside the other tray. In the last condition, both trays contained bait, but one of the trays had a small gap which prevented the elephants from reaching the reward. Subjects were required to choose and pull either tray with their trunk and to obtain the bait (i.e. goal). Results showed that one elephant performed all of the support problems significantly above chance after several sessions, suggesting that the elephant was capable of understanding that pulling the tray was the “means” for achieving the “end” of obtaining the bait. This study showed that elephants show means–end behavior when subjected to a Piagetian “support” task, and indicates that such goal-directed behavior occurs in species other than primates.     

Rapid solving of a problem apparatus by juvenile black-throated monitor lizards (Varanus albigularis albigularis)

It is widely accepted that providing stimulus enrichment is an important part of the development and maintenance of behavior and well-being in mammals. However, extending this idea to non-avian reptiles has barely been explored, certainly as an aid to cognitive development. Monitor lizards have a reputation for being highly curious and intelligent lizards, but quantitative experiments are necessary to evaluate such impressions as well as the value of providing enrichment to captive squamate reptiles. In this study eight juvenile black-throated monitors, Varanus albigularis, were tested in their home enclosures with three presentations, at weekly intervals, of a novel task apparatus: a transparent food tube containing several prey. The food tube allowed the monitors to obtain prey by using hinged doors at either end of the tube to access food. All eight lizards learned to open the tube, insert head, and capture the prey within 10 min in the first trial. By the second trial, both mean latencies to access the tube and capture the first prey item decreased significantly, as did the use of ineffective responses such as shaking the tube. A further slight decrease occurred in the third trial. Due to the results of this and similar studies, serious consideration should be given to further testing of cognitive abilities in squamate reptiles. Incorporating problem solving tasks may also be useful to increase the activity level and captive well-being of squamate reptiles, especially monitor lizards.     

Spontaneous performance of wild baboons on three novel food-access puzzles

Although the technical problem-solving expertise of nonhuman primates has been investigated extensively in captivity, few species have been tested in their natural habitats. Here I examine the physical cognition of wild savanna baboons (Papio anubis), a species that occupies an omnivorous foraging niche in which a variety of embedded food items are extracted and processed. Baboons were tested on three puzzles, each involving high-quality food that required removal from a novel obstruction: (1) a string-pulling puzzle in which food was hung from tree branches, (2) a twig-dipping puzzle in which food was embedded in a vertical tube, and (3) a stick-pushing puzzle in which food was contained in a horizontal conduit. The baboons failed to solve the second and third puzzles even when tools had been appropriately positioned in advance. And although they solved the first puzzle, their actions (running while holding food that was still attached to the string), suggested they did not fully comprehend the string’s connective property. The baboons’ performance might reflect the time constraints of life in the wild, which relative to captivity may provide fewer opportunities for the development of understanding about the physical properties of objects and their potential uses as tools. Further experiments on the physical cognition of baboons and many other primate species in their natural habitats would help test this ontogenetic hypothesis. Such field experiments would be especially fruitful if they continued to target extractive foragers like baboons: these experiments could simultaneously provide a test of phylogenetic hypotheses that invoke extractive foraging as the key stimulus for brain expansion in savanna-dwelling hominids. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.