Instrumental responding following reinforcer devaluation

In two experiments, hungry rats were given instrumental lever-press training for an appetitive reinforcer and, in addition, were exposed to another type of food which was not contingent on lever pressing. In the first experiment, exposure to each type of food was on separate days, whereas in the second experiment rats were exposed to each type of food in strict alternation within each session. Subsequently, a food aversion was conditioned to the reinforcer for the experimental group and to the non-contingent food for the control group. In both experiments, animals with an aversion to the reinforcer responded less in an extinction test than animals with an aversion to the non-contingent food. Subsequent reacquisition tests confirmed that the aversion to the non-contingent food in the control group was of comparable strength with that to the reinforcer in the experimental group. The results were discussed in terms of whether the reinforcer is encoded in the associative structure set up by exposure to an instrumental contingency.     

Identifying subgroups that succeed or fail with three levels of physical activity intervention: the Activity Counseling Trial.

The authors used recursive partitioning methods to identify combinations of baseline characteristics that predict 2-year physical activity success in each of 3 physical activity interventions delivered in the multisite Activity Counseling Trial. The sample consisted of 874 initially sedentary primary care patients, ages 35-75 years, who were at risk for cardiovascular disease. Predictors of 2-year success were specific to each intervention and represented a range of domains, including physiological, demographic, psychosocial, health-related, and environmental variables. The results indicate how specific patient subgroups (e.g., obese, unfit individuals; high-income individuals in stable health) may respond differently to varying levels and amounts of professional assistance and support. The methods used provide a practical first step toward identifying clinically meaningful patient subgroups for further systematic investigation.     

Circumstances and Outcomes of a Firearm Seizure Law: Marion County,Indiana, 2006–2013

Indiana statute allows police to seize firearms without a warrant if the officer believes a person meets the law's definition of “dangerous.” Review of the use of this law in Marion County (Indianapolis), Indiana, showed that prosecutors filed petitions in court to retain weapons seized by police under this law 404 times between 2006 and 2013. Police removed weapons from people due to identification of a risk of suicide (68%) or violence (21%), or the presence of psychosis (16%). The firearm seizures occurred in the context of domestic disputes in 28% of cases and intoxication was noted in 26% of cases. There were significant demographic differences in the circumstances of firearm seizures and the firearms seized. The seized firearms were retained by the court at the initial hearing in 63% of cases; this retention was closely linked to the defendant's failure to appear at the hearing. The court dismissed 29% of cases at the initial hearing, closely linked to the defendant's presence at the hearing. In subsequent hearings of cases not dismissed, the court ordered the destruction of the firearms in 72% of cases, all when the individual did not appear in court, and dismissed 24% of the cases, all when the individual was present at the hearing. Overall, the Indiana law removed weapons from a small number of people, most of whom did not seek return of their weapons. The firearm seizure law thus functioned as a months-long cooling-off period for those who did seek the return of their guns. Copyright © 2015 John Wiley & Sons, Ltd.