The Representation of Geometric Cues in Infancy

There is evidence that, from an early age, humans are sensitive to spatial information such as simple landmarks and the size of objects. This study concerns the ability to represent a particular kind of spatial information, namely, the geometry of an enclosed layout—an ability present in older children, adults, and nonhuman animals (e.g., Cheng, 1986; Hermer & Spelke, 1996). Using a looking‐time procedure, 4.5‐ to 6.5‐month‐olds were tested on whether they could distinguish among the corners of an isosceles triangle. On each trial, the target corner was marked by a red dot. The stimulus (triangle with dot) appeared from different orientations across trials, ensuring that only cues related to the triangle itself could be used to differentiate the corners. When orientations were highly variable, infants discriminated the unique corner (i.e., the corner with the smaller angle and two equal‐length sides) from a nonunique corner; they could not discriminate between the two nonunique corners. With less variable orientations, however, infants did discriminate between the nonunique corners of the isosceles triangle. Implications for how infants represent geometric cues are discussed.     

Convergence of Heavy-tailed Monte Carlo Markov Chain Algorithms

Abstract.  In this paper, we use recent results of Jarner & Roberts ( Ann. Appl. Probab., 12, 2002, 224) to show polynomial convergence rates of Monte Carlo Markov Chain algorithms with polynomial target distributions, in particular random-walk Metropolis algorithms, Langevin algorithms and independence samplers. We also use similar methodology to consider polynomial convergence of the Gibbs sampler on a constrained state space. The main result for the random-walk Metropolis algorithm is that heavy-tailed proposal distributions lead to higher rates of convergence and thus to qualitatively better algorithms as measured, for instance, by the existence of central limit theorems for higher moments. Thus, the paper gives for the first time a theoretical justification for the common belief that heavy-tailed proposal distributions improve convergence in the context of random-walk Metropolis algorithms. Similar results are shown to hold for Langevin algorithms and the independence sampler, while results for the mixing of Gibbs samplers on uniform distributions on constrained spaces are rather different in character.     

The Effects of Praising Qualifying Autoclitics on the Frequency of Reading

In the current study, tacts with positive qualifying autoclitics for reading were reinforced in order to determine if this procedure would increase the time spent reading by participants. Participants included 5 children, between 9–10 years old. Participants were individually exposed to 4 free operant sessions during which they were instructed to independently choose play activities. During pre- and post-treatment conditions, no consequences were provided for choosing reading. In addition, 4 treatment sessions were conducted on days separate from the free operant session days, during which the experimenter praised each positive reading-related statement emitted by the participant. Following treatment sessions, 4 out of 5 participants increased the time allocated to reading, suggesting that reading could be increased when praise is delivered contingent upon positive reading-related verbalizations.     

Linking Financial Strain to Marital Instability: Examining the Roles of Emotional Distress and Marital Interaction

Using a sample consisting of 4,997 married couples from the National Survey of Families and Households, individual emotional distress, the occurrence of couple disagreements, couple fighting, and couple quality time together mediated the relationship between financial strain and personal assessments of marital instability. The overall results suggest that financial strain influences both positive and negative forms of couple interaction which are stronger mediators than personal emotional distress of the relationship between financial strain and marital instability. The results further suggest that there were no gender differences among these linkages.     

Clinical assessment of maladjusted preschool children

The authors stress that total assessment prior to intervention is crucial, including standardized testing, observations of behavior, developmental history, and play interview. Techniques presented provide a holistic approach for evaluating the referred preschool child.