Influence of the large-small split effect on strategy choice in complex subtraction.

Two main theories have been used to explain the arithmetic split effect: decision-making process theory and strategy choice theory. Using the inequality paradigm, previous studies have confirmed that individuals tend to adopt a plausibility-checking strategy and a whole-calculation strategy to solve large and small split problems in complex addition arithmetic, respectively. This supports strategy choice theory, but it is unknown whether this theory also explains performance in solving different split problems in complex subtraction arithmetic. This study used small, intermediate and large split sizes, with each split condition being further divided into problems requiring and not requiring borrowing. The reaction times (RTs) for large and intermediate splits were significantly shorter than those for small splits, while accuracy was significantly higher for large and middle splits than for small splits, reflecting no speed-accuracy trade-off. Further, RTs and accuracy differed significantly between the borrow and no-borrow conditions only for small splits. This study indicates that strategy choice theory is suitable to explain the split effect in complex subtraction arithmetic. That is, individuals tend to choose the plausibility-checking strategy or the whole-calculation strategy according to the split size.

Psychosomatic Status, Personality Traits, and Coping Styles of Bereaved and Non-Bereaved Survivors of the 2008 Wenchuan Earthquake, China.

OBJECTIVES: This study examined personality, coping styles, and psychosomatic characteristics and their relationships in bereaved and non-bereaved earthquake survivors. STUDY DESIGN: Cross-sectional survey. METHODS: A survey was conducted with a sample of 102 non-bereaved survivors and 79 bereaved survivors from Mianyang, Anyang, and similar districts 2 weeks after Wenchuan earthquake. Survivors completed questionnaires, including items about demographics, personality characteristics, coping styles, and psychosomatic status. RESULTS: Bereaved survivors had lower scores for gregariousness, trust, and optimism, but higher scores for depressed mood, loneliness, becoming easily fearful, irritation, and anxiety than non-bereaved survivors. In addition, bereaved participants scored higher for avoiding problems, self-blame, and fantasy coping styles than non-bereaved ones. Personality and coping styles significantly correlated with psychosomatic status in bereaved and non-bereaved survivors. Optimism and openness to feelings personality characteristics, and self-blame, avoiding problems, and rationalization coping styles significantly predicted psychosomatic status of bereaved survivors, whereas openness to fantasy, optimism, order, and trust personality characteristics, and self-blame and avoiding problems coping styles significantly predicted psychosomatic status of non-bereaved survivors. CONCLUSION: Earthquake survivors experienced post-traumatic stress disorder (PTSD) symptoms and negative emotions. Bereaved survivors experienced more serious PTSD symptoms and negative emotions relative to non-bereaved survivors. Appropriate psychological crisis interventions should be conducted for earthquake survivors, especially bereaved survivors.

Arithmetic split effect in complex subtractions: an event-related potential study.

This study explores the relationship between the split effect and the use of exact versus approximate strategies in complex-subtraction calculations. One-hundred and two-digit subtraction problems were presented, with half of them being small-split problems with answers ±2 or ±5 from 50 and the other half being large-split problems with answers ±10 or ±15 from 50. Participants were asked to indicate whether the answer was less than 50. The measures were speed and accuracy of task performance, and high temporal resolution event-related potentials. Behavioral data showed that participants had a longer time requirement and a lower accuracy in solving small-split problems than in solving large-split problems. Event-related potential data show that, comparatively, the small-split problems led to more-negative, more-lateralized waves as early as 250 ms at frontal, frontocentral, and central sites. Our results, which are in agreement with previous studies, suggest that the participants used exact strategies to solve small-split problems and approximate strategies to solve large-split problems when performing complex subtractions. These results further our understanding of the brain mechanisms underlying the relationship between small/large-split effects and exact/approximate strategies in this task domain.

SLOW WALKER1, essential for gametogenesis in Arabidopsis, encodes a WD40 protein involved in 18S ribosomal RNA biogenesis.

The progression of mitotic division cycles and synchronous development between and within the male and female reproductive organs are essential for plant sexual reproduction. Little is known about the genetic control of the progression of mitotic cycles of the haploid genome during gametogenesis in higher plants. Here, we report the phenotypic and molecular characterization of an Arabidopsis thaliana mutant, slow walker1 (swa1), in which the progression of the mitotic division cycles of the female gametophyte was disrupted. Confocal microscopy revealed that megagametophyte development was asynchronous in swa1, causing embryo sacs to arrest at two-, four-, or eight-nucleate stages within the same pistil. A delayed pollination experiment showed that a small fraction of the swa1 embryo sacs were able to develop into functional female gametophytes. The swa1 mutation also showed a slight reduction in penetrance through the male gametophyte, although the pollen grains were morphologically normal. Molecular analysis indicates that SWA1 encodes a protein with six WD40 repeats that is localized in the nucleolus in interphase cells. The SWA1 gene is expressed in cells undergoing active cell divisions, including functional megaspores and the female gametophytic cells. RNA interference results indicated that knockout of SWA1 inhibited root growth significantly and led to the accumulation of unprocessed 18S pre-rRNA. These data suggest that SWA1 most likely plays a role in rRNA biogenesis that is essential for the progression of the mitotic division cycles during gametogenesis in plants.