Metacognitive inferences in source memory judgements: the role of perceived differences in item recognition

This research investigated the hypothesis that metacognitive inferences in source memory judgements are based on the recognition or nonrecognition of an event together with perceived or expected differences in the recognizability of events from different sources. The hypothesis was tested with a multinomial source-monitoring model that allowed separation of source-guessing tendencies for recognized and unrecognized items. Experiments 1A and 1B manipulated the number of item presentations as relevant source information and revealed differential guessing tendencies for recognized and unrecognized items, with a bias to attribute unrecognized items to the source associated with poor item recognition. Experiments 2A and 2B replicated the findings with a manipulation of presentation time and extended the analysis to subjective differences in item recognition. Experiments 3A and 3B used more natural source information by varying type of acoustic signal and demonstrated that subjective theories about differences in item recognition are sufficient to elicit differential source-guessing biases for recognized and unrecognized items. Together the findings provide new insights into the cognitive processes underlying source memory decisions, which involve episodic memory and reconstructive tendencies based on metacognitive beliefs and general world knowledge.     

Effectiveness of dialectical behaviour therapy for borderline personality disorder in an inpatient setting

This study evaluates the effectiveness of dialectical behaviour therapy (DBT) for borderline personality disorder (BPD) in an unselected, comorbid population seeking 3-month inpatient treatment. We studied 50 consecutively admitted individuals (44 women, six men) with BPD as defined by DSM-IV at three time points (at admission, at discharge, and at the 15-month follow-up). For the clinical diagnoses, we used the Structured Clinical Interview for DSM-IV (SCID) and compared the frequencies of comorbid axis I and axis II disorders at admission and at the 15-month follow-up. Overall, participants showed a high degree of comorbidity. Psychopathology was significantly reduced at post-treatment and at follow-up. Effect sizes for outcome measures were within the range of those of previous studies. Our findings support the notion that the results of the DBT efficacy research can be generalized to an inpatient setting and to patients with BPD disorder with high comorbidity.     

Early changes in muscle activation patterns of toddlers during walking

Early locomotor behavior has been the focus of considerable attention by developmentalists over several decades. Few studies have addressed explicitly patterns of muscle activity that underlie this coordination pattern. Our purposes were to illustrate a method to determine objectively the onset and offset of muscle firings during early walking and to investigate the emergence of patterns of activation of the core locomotor muscles. We tested eight toddlers as they walked overground at walking onset (max. of 3-6 independent steps) and after three months of walking experience. Surface electrodes monitored activity of the gastrocnemius, tibialis anterior, quadriceps, and hamstrings. We reduced EMG signals to a frame-by-frame designation of "on-off," followed by muscle state and co-contraction analyses, and probability distributions for each muscle's activity across multiple cycles. Our results clearly show that at walking onset muscle activity was highly variable with few, if any, muscles showing recurring patterns of behavior, within or among toddlers. Variability and co-activation decreased with walking experience but remained inconsistent, in contrast to the significant increase in stability shown for joint coordination and endpoint (foot placement) parameters. We propose this trend emerges because of the high number of options (muscle combinations) available. Toddlers learn first to marshal sufficient force to balance and make forward progress but slowly discover how to optimize these resources.     

On how to be unpredictable: evidence from the voluntary task-switching paradigm

The voluntary task-switching paradigm requires subjects to select randomly between tasks and promises to provide a window into executive task selection independent of exogenous influences present in standard task-switching situations. We show here that the degree to which subjects perseverate on tasks across trials captures unique individual differences variance, but also that the switch rate is under strong stimulus-driven control: "Voluntary" switches are much more frequent when the stimulus changes than when it repeats. Most important, we show that individuals whose no-switch trials are selectively slowed exhibit less perseveration and stimulus-driven effects (and thus more voluntary selection) than individuals whose no-switch trials do not show this slowing. We suggest that selective slowing indicates a strategy of treating trials as discrete events--possibly through inhibition of the preceding task set. These results not only demonstrate massive nonvoluntary influences on voluntary selection that are largely untapped by standard task-switching measures, but also show how such influences can be counteracted through strategic adaptations.