Effects of class-interval size upon certain frequency distributions of interresponse times

Inter-response time distributions with class intervals of 0.05 and 0.04 sec revealed characteristics not observable with class intervals of 0.5 sec or greater. Bimodalities were clearly evident in the inter-response time distributions for two out of three pigeons. These modes seemed to correspond to two discrete response topographies.     

Alignable and nonalignable differences in causal explanations

Prior research indicates that people may base their causal explanations on distinctive features between an event and a contrasting background instance in which the event did not occur. Research on similarity judgments suggests that there are two types of distinctive features: alignable differences, which are corresponding characteristics of a pair, and nonalignable differences, which are characteristics of one item for which there are no corresponding characteristics in the other. In three experiments, the hypothesis that people's evaluations of causal explanations vary as a function of feature alignment was examined. The results suggest that people will rate explanations differently on the basis of alignable or nonalignable differences, depending on the type of the event, and that alignability depends on the relational structure among the features of the event.     

Accuracy of Clinician Predictions of Future Self‐Harm: A Systematic Review and Meta‐Analysis of Predictive Studies

Assessment of a patient after hospital‐treated self‐harm or psychiatric hospitalization often includes a risk assessment, resulting in a classification of high risk versus low risk for a future episode of self‐harm. Through systematic review and a series of meta‐analyses looking at unassisted clinician risk classification (eight studies; N = 22,499), we found pooled estimates for sensitivity 0.31 (95% CI: 0.18–0.50), specificity 0.85 (0.75–0.92), positive predictive value 0.22 (0.21–0.23), and negative predictive value 0.89 (0.86–0.92). Clinician classification was too inaccurate to be clinically useful. After‐care should therefore be allocated on the basis of a needs rather than risk assessment.