Measuring individual differences in statistical learning: Current pitfalls and possible solutions

Most research in statistical learning (SL) has focused on the mean success rates of participants in detecting statistical contingencies at a group level. In recent years, however, researchers have shown increased interest in individual abilities in SL, either to predict other cognitive capacities or as a tool for understanding the mechanism underlying SL. Most if not all of this research enterprise has employed SL tasks that were originally designed for group-level studies. We argue that from an individual difference perspective, such tasks are psychometrically weak, and sometimes even flawed. In particular, the existing SL tasks have three major shortcomings: (1) the number of trials in the test phase is often too small (or, there is extensive repetition of the same targets throughout the test); (2) a large proportion of the sample performs at chance level, so that most of the data points reflect noise; and (3) the test items following familiarization are all of the same type and an identical level of difficulty. These factors lead to high measurement error, inevitably resulting in low reliability, and thereby doubtful validity. Here we present a novel method specifically designed for the measurement of individual differences in visual SL. The novel task we offer displays substantially superior psychometric properties. We report data regarding the reliability of the task and discuss the importance of the implementation of such tasks in future research.     

When children ask, "What is it?" what do they want to know about artifacts?

When children ask, "What is it?" are they seeking information about what something is called or what kind of thing it is? To find out, we gave 2-, 3-, and 4-year-olds (32 at each age) the opportunity to inquire about unfamiliar artifacts. An ambiguous question was answered with a name or with functional information, depending on the group to which the children were assigned. Children were inclined to follow up with additional questions about the object when they had been told its name, but seemed satisfied with the answer when they had been told the object's function. Moreover, children in the name condition tended to substitute questions about function for ambiguous questions over the course of the session. These results indicate that children are motivated to discover what kinds of things novel artifacts are, and that young children, like adults, conceive of artifact kinds in terms of their functions.     

Self‐Harm in Young Offenders

The prevalence and correlates of self‐harm and suicidal behavior in 515 young offenders (mean age 17.3 years, SD = 1.7) serving community‐based orders (CBOs; n = 242) or custodial sentences (n = 273) in Victoria, Australia, are described. Results from structured interviews showed that 83 (16.1%) participants reported self‐harming in the previous 6 months, and this was more common among those serving custodial sentences than those serving CBOs (19.4% vs. 12.4%; OR 3.10, 95% CI: 1.74–5.55). Multiple incidents were more common in females and 24% (95% CI: 19–39) of participants who had self‐harmed reported having done so with suicidal intent. Self‐harm was associated with recent bullying victimization, expulsion from school, past year violent victimization, cannabis dependence, and risk‐taking behavior in the preceding year. The epidemiological profile of self‐harm in this population appears to be distinct from that seen in the general population. Young offenders who self‐harm are a vulnerable group with high rates of psychiatric morbidity, substance misuse problems, and social risk factors. They may benefit from targeted psychological interventions designed specifically to address impulsivity, delivered both within–and during the transition from–the youth justice system.     

Investigating the Co‐Occurrence of Self‐Mutilation and Suicide Attempts among Opioid‐Dependent Individuals

The prevalence and risk factors associated with self‐mutilation among opioid dependent cases and controls were determined, and the co‐occurrence of self‐mutilation and attempted suicide was examined. The prevalence of self‐mutilation among cases and controls did not differ significantly (25% vs. 23%, respectively), with gender differences identified among cases only. A number of risk factors were found to be associated with self‐mutilation, including borderline personality disorder, alcohol dependence, childhood sexual abuse, and multiple suicide attempts. Not only is self‐mutilation a clinically significant problem, but when combined with a history of attempted suicide, the psychological dysfunction observed is markedly high.     

Does adolescent heavier alcohol use predict young adult aggression and delinquency? Parallel analyses from four Australasian cohort studies

While the association between heavy alcohol consumption and aggression has been well documented, the causal direction of this association, particularly at a population level, is disputed. A number of causal sequences have been proposed. First, that aggression leads to heavy alcohol use. Second, that heavy alcohol use leads to aggression. Third, that the association between alcohol use and aggression is due to confounding by (a) sociodemographic variables or (b) delinquency. We report here data from four Australasian prospective longitudinal studies of adolescents, to assess the temporal sequence of heavy drinking and aggression over the period from adolescence to young adulthood. The four cohort studies provide a total sample of 6,706 persons (Australian Temperament Project, n = 1701; Christchurch Health and Development Study, n = 931; Mater-University of Queensland Study of Pregnancy, n = 2437; Victorian Adolescent Health Cohort Study, n = 1637). We use multinomial logistic regression to determine whether early adolescent aggression predicts subsequent age of onset of heavy episodic drinking (HED), after adjustment for concurrent sociodemographic factors and delinquency. We then consider whether HED predicts subsequent aggression, after adjusting for past aggression, concurrent delinquency, and a range of confounders. There are broadly consistent findings across the four cohort studies. Early aggression strongly predicts subsequent HED. HED predicts later aggression after adjustment for prior aggression and other confounders. Policies that alter population levels of alcohol consumption are likely to impact on levels of aggression in societies where HED linked to aggression is more common.