Mental multiplication: Nothing but the facts?

Current models of adult arithmetic performance assume that representation includes only facts and procedures. However, other kinds of representations such as an analog scale or sets of number multiples might be useful in a variety of multiplication-related tasks. Introducing the practice transfer paradigm, we demonstrate that associations between distinct representational structures can be detected via cross-task transfer, provided that initial performance is retrieval based. Results support the predictions of the integrated-structures model of multiplication knowledge. Implications for well-established item differences such as the problem-size effect are addressed, and the question of how integration occurs is considered.     

Conduct Disorder in Girls: A Review of the Literature

The study of Conduct Disorder (CD) has primarily been limited to boys. The lack of research resulted from a premise that CD in girls was rare. However, CD in girls is a relatively common psychiatric diagnosis, and appears to be associated with several serious outcomes, such as Antisocial Personality Disorder and early pregnancy. Understanding gender differences in the course and severity of CD may lead to important information about etiology. Empirical studies on precursors, developmental course, risk factors and treatment for CD in girls are reviewed, while highlighting similarities and differences between girls and boys. Generally, CD symptoms in girls are stable. Precursors to CD in girls probably include Oppositional Defiant Disorder and temperamental factors, but also may include certain negative cognitions. What distinguishes CD in girls is the high risk they have to develop comorbid conditions, especially internalizing disorders. Risk factors for CD in girls partly overlap with those known for boys, but some factors appear to be highly salient for girls. Finally, there may be some significant effects of gender on treatment efficacy. Implications of these findings for future etiologic research are discussed.     

A discrimination analysis of training-structure effects on stimulus equivalence outcomes.

Experiments designed to establish stimulus equivalence classes frequently produce differential outcomes that may be attributable to training structure, defined as the order and arrangement of baseline conditional discrimination training trials. Several possible explanations for these differences have been suggested. Here we develop a hypothesis based on an analysis of the simple simultaneous and successive discriminations embedded in conditional discrimination training and testing within each of the training structures that are typically used in stimulus equivalence experiments. Our analysis shows that only the comparison-as-node (many-to-one) structure presents all the simple discriminations in training that are subsequently required for consistently positive outcomes on all tests for the properties of equivalence. The sample-as-node (one-to-many) training structure does not present all the simple discriminations required for positive outcomes on either the symmetry or combined transitivity and symmetry (equivalence) tests. The linear-series training structure presents all the simple discriminations required for consistently positive outcomes on tests for symmetry, but not for symmetry and transitivity combined (equivalence) or transitivity alone. Further, the difference in the number of simple discriminations presented in comparison-as-node training versus the other training structures is larger when the intended class size is greater than three or the number of classes is larger than two. We discuss the relevance of this analysis to interpretations of stimulus equivalence research, as well as some methodological and theoretical implications.     

A cautionary note on using internal cross validation to select the number of clusters

A highly popular method for examining the stability of a data clustering is to split the data into two parts, cluster the observations in Part A, assign the objects in Part B to their nearest centroid in Part A, and then independently cluster the Part B objects. One then examines how close the two partitions are (say, by the Rand measure). Another proposal is to split the data into k parts, and see how their centroids cluster. By means of synthetic data analyses, we demonstrate that these approaches fail to identify the appropriate number of clusters, particularly as sample size becomes large and the variables exhibit higher correlations.The authors express their thanks to the Sol C. Snider Entrepreneurial Center, Wharton School, for support of this project.     

Amount of reward has opposite effects on the discounting of delayed and probabilistic outcomes

Previous research has shown that the value of large future rewards is discounted less steeply than is the value of small future rewards. These experiments extended this line of research to probabilistic rewards. Two experiments replicated the standard findings for delayed rewards but demonstrated that amount has an opposite effect on the discounting of probabilistic rewards. That is, large probabilistic amounts were discounted at the same or higher rates than small amounts. Although amount had opposite effects on the discounting of delayed and probabilistic rewards, nevertheless, the same form of mathematical function accurately described discounting of both types of reward. The findings suggest that fundamentally similar, but not identical, processes are involved in decision making regarding delayed and probabilistic rewards. The implications of these findings for impulsivity and self-control are discussed.     

Reducing indices of unhappiness among individuals with profound multiple disabilities during therapeutic exercise routines.

A program was developed to reduce indices of unhappiness that accompanied therapeutic exercise routines among people with profound multiple disabilities. Indices of unhappiness were recorded, using an observation system that had been validated through previous research involving happiness-related variables, while support personnel conducted exercises with 3 participants. A multicomponent program was then implemented that involved presenting highly preferred stimuli before, during, and after each exercise session. Results indicated that the program was accompanied by reduced indices of unhappiness for each participant relative to the traditional method of conducting the exercises, although changes in the preferred stimuli used with 1 participant were required before consistent reductions occurred. Results are discussed regarding the importance of reducing unhappiness indices as a means of enhancing aspects of the daily quality of life for people with profound multiple disabilities. Areas for future research are also discussed, focusing on expanding the unhappiness-reduction procedures to other routine events that may occasion indices of unhappiness.     

Intersensory conflict between vision and touch: the response modality dominates when precise, attention-riveting judgments are required

In four experiments, reducing lenses were used to minify vision and generate intersensory size conflicts between vision and touch. Subjects made size judgments, using either visual matching or haptic matching. In visual matching, the subjects chose from a set of visible squares that progressively increased in size. In haptic matching, the subjects selected matches from an array of tangible wooden squares. In Experiment 1, it was found that neither sense dominated when subjects exposed to an intersensory discrepancy made their size estimates by using either visual matching or haptic matching. Size judgments were nearly indentical for conflict subjects making visual or haptic matches. Thus, matching modality did not matter in Experiment 1. In Experiment 2, it was found that subjects were influenced by the sight of their hands, which led to increases in the magnitude of their size judgments. Sight of the hands produced more accurate judgments, with subjects being better able to compensate for the illusory effects of the reducing lens. In two additional experiments, it was found that when more precise judgments were required and subjects had to generate their own size estimates, the response modality dominated. Thus, vision dominated in Experiment 3, where size judgments derived from viewing a metric ruler, whereas touch dominated in Experiment 4, where subjects made size estimates with a pincers posture of their hands. It is suggested that matching procedures are inadequate for assessing intersensory dominance relations. These results qualify the position (Hershberger & Misceo, 1996) that the modality of size estimates influences the resolution of intersensory conflicts. Only when required to self-generate more precise judgments did subjects rely on one sense, either vision or touch. Thus, task and attentional requirements influence dominance relations, and vision does not invariably prevail over touch.     

Stepfamilies Doing Family: A Meta‐Ethnography

The present review examines how stepfamily members without a shared history co‐construct a shared family identity and what family processes are relevant in this stepfamily formation. Three databases (Web of Science, PsycInfo, and ProQuest) were systematically searched, resulting in 20 included qualitative studies. The meta‐ethnography approach of Noblit and Hare allowed synthesizing these qualitative studies and constructing a comprehensive framework of stepfamilies doing family. Three interdependent family tasks were identified: (a) honoring the past, (b) marking the present, and (c) investing in the future. Stepfamily members’ experiences of these family tasks are strongly affected by the dominant societal perspectives and characterized by an underlying dialectical tension between wanting to be like a first‐time family and feeling the differences in their family structure at the same time. These findings clearly demonstrate the family work that all stepfamily members undertake and provide a broader context for interpreting stepfamilies’ co‐construction of a new family identity.     

Controlling for Prior Attainment Reduces the Positive Influence that Single-Gender Classroom Initiatives Exert on High School Students’ Scholastic Achievements

Research points to the positive impact that gender-segregated schooling and classroom initiatives exert on academic attainment. An evaluation of these studies which reveal positive effects highlights, however, that students are typically selectively assigned to single- or mixed-gender instructional settings, presenting a methodological confound. The current study controls for students’ prior attainment to appraise the efficacy of a single-gender classroom initiative implemented in a co-educational high school in the United Kingdom. Secondary data analysis (using archived data) was performed on 266 middle-ability, 11–12 year-old students’ standardized test scores in Languages (English, foreign language), STEM-related (Mathematics, Science, Information and Communication Technology), and Non-STEM subjects (art, music, drama). Ninety-eight students (54, 55% female) were taught in single-gender and 168 (69, 41% female) in mixed-gender classrooms. Students undertook identical tests irrespective of classroom type, which were graded in accordance with U.K national curriculum guidelines. Controlling for students’ prior attainment, findings indicate that students do not appear to benefit from being taught in single-gender relative to mixed-gender classrooms in Language and STEM-related subjects. Young women benefitted from being taught in mixed-gender relative to single-gender classes for Non-STEM subjects. However, when prior ability is not controlled for, the intervention appears to be effective for all school subjects, highlighting the confounding influence of selective admissions. These findings suggest that gender-segregated classroom initiatives may not bolster students’ grades. It is argued that studies that do not control for selection effects may tell us little about the effectiveness of such interventions on scholastic achievement.