External validity of conduct and oppositional defiant disorders determined by the NIMH Diagnostic Interview Schedule for children.

We administered the Diagnostic Interview Schedule for Children (DISC) two times to a group of youth (222 boys, 147 girls) entering residential care, once at their time of entry and once 1 year later. We then compared their DISC outcomes on Conduct Disorder (CD) and Oppositional Defiant Disorder (ODD) against changes in independent direct observations of diagnostically relevant behavior obtained over the course of that year. Results from hierarchical linear modeling analyses showed significant discriminative relationships between results from the DISC and the independent observations. Specifically, observations of symptomatic behaviors (CD or ODD) decreased for youth who met diagnostic criteria at the first administration of the DISC but not at the second, increased for youth who did not meet criteria at the first administration but did at the second, and did not change for youth who met criteria at both administrations. These results extend the data on the validity of the DISC and support continued research efforts to determine its clinical utility.

How baseball outfielders determine where to run to catch fly balls.

Current theory proposes that baseball outfielders catch fly balls by selecting a running path to achieve optical acceleration cancellation of the ball. Yet people appear to lack the ability to discriminate accelerations accurately. This study supports the idea that outfielders convert the temporal problem to a spatial one by selecting a running path that maintains a linear optical trajectory (LOT) for the ball. The LOT model is a strategy of maintaining "control" over the relative direction of optical ball movement in a manner that is similar to simple predator tracking behavior.