Timing variability in circle drawing and tapping: probing the relationship between event and emergent timing

R. Ivry, R. M. Spencer, H. N. Zelaznik, and J. Diedrichsen (2002) have proposed a distinction between timed movements in which a temporal representation is part of the task goal (event timing) and those in which timing properties are emergent. The issue addressed in the present experiment was how timing in conditions conducive to emergent timing becomes established. According to what the authors term the transformation hypothesis, timing initially requires an event-based representation when the temporal goal is defined externally (e.g., by a metronome), but over the first few movement cycles, control processes become established that allow timing to become emergent. Different groups of participants (N = 84) executed either 1 timed interval, 4 timed intervals, or 2 timed intervals separated by a pause. They produced the intervals by either circle drawing, a task associated with emergent timing, or tapping, a task associated with event timing. Analyses of movement variability suggested that similar timing processes were used in the 2 tasks only during the 1st interval. Those results are consistent with the transformation hypothesis and lead to the inference that the transition from event-based control to emergent timing can occur rapidly during continuous movements.     

Bridging the gap between brain and behavior: cognitive and neural mechanisms of episodic memory

The notion that non-human animals are capable of episodic memory is highly controversial. Here, we review recent behavioral work from our laboratory showing that the fundamental features of episodic memory can be observed in rats and that, as in humans, this capacity relies on the hippocampus. We also discuss electrophysiological evidence, from our laboratory and that of others, pointing to associative and sequential coding in hippocampal cells as potential neural mechanisms underlying episodic memory.     

Intervention Groups for Adolescents With Conduct Problems: Is Aggregation Harmful or Helpful?

Past research has suggested that the aggregation of deviant peers during treatment may cause harmful effects (T. J. Dishion, J. McCord, & F. Poulin, 1999). This study compared the effectiveness of problem-solving skills training groups in which all members had conduct problems (pure group condition) with groups that consisted of adolescents with and without behavior problems (mixed group condition). Participants were 139 sixth- and seventh-graders (mean age = 12.7; 63% male; 55% White) enrolled at public middle schools. Pre-, post-, and 6-month follow-up data were collected, along with intervention process variables. Results showed that, contrary to the deviancy training hypothesis, adolescents in the pure-group condition engaged in more adaptive in-session behavior and received lower scores on the parent and teacher ratings of externalizing behavior at postintervention than those in the mixed-group condition. Mediation analyses showed that the deviancy training that occurred in the mixed-group condition accounted for their worse postintervention scores, findings consistent with the deviancy training hypothesis.     

Significance of Childhood Conduct Problems to Later Development of Conduct Disorder Among Children With ADHD: A Prospective Follow-Up Study

This study investigates whether low to moderate levels of childhood oppositional defiant disorder (ODD) and conduct disorder (CD) behaviors contribute to the development of clinically diagnosed CD in adolescence, in children with attention deficit hyperactivity disorder (ADHD). Participants were 207 White boys (ages 6-12) with ADHD free of conduct disorder diagnoses. Parent and teacher ratings were obtained. Participants were assessed at mean age 18 by clinicians blind to childhood status. A non-ADHD group (recruited in adolescence) was also studied. ODD behavior ratings did not predict CD in adolescence, whereas CD behavior ratings did. No single ODD or CD behavior predicted adolescent outcome. ADHD probands with very low ratings (Not at all, Just a little) by parents and teachers on all CD behaviors were still at significantly increased risk for CD in adolescence, compared to non-ADHD controls. The same relationships were found between childhood ODD and CD behaviors, and antisocial personality disorder in adulthood (mean age, 25). We conclude that childhood ADHD is a developmental precursor of later antisocial disorder, even in the absence of comorbid ODD or CD in childhood. However, low levels of CD-type problems are not innocuous, because they predict later CD among children with ADHD without comorbid CD.     

Group therapy for depressed elderly women

We describe and evaluate a group therapy program targeting depression among elderly residents (N=303) of subsidized high-rise apartments in Nashville, TN. This eclectic program was comprised of 12 sessions (a total of 24 hours) that included modules on exercise and preventive health behaviors, cognitive and re-motivation therapy, reminiscence and grief therapy, and social skills development. Our multivariate regression analyses of pre-post measures using the Geriatric Depression Scale (GDS) showed that the effects of the group therapy varied by race, age, and level of initial depression among the participants. The program was effective in reducing depression, but only among Caucasian women who reported at least moderate depression prior to the program, and it yielded greater benefits for women between 55 and 75 years of age.     

Detection of counter-changing contrast: second-order apparent motion without postrectification motion-energy analysis or salience mapping/feature tracking

The perception of 2nd-order, texture-contrast-defined motion was studied for apparent-motion stimuli composed of a pair of spatially displaced, simultaneously visible checkerboards. It was found that background-relative, counter-changing contrast provided the informational basis for the perception of 2nd-order apparent motion; motion began where contrast changed toward the contrast value of the background checkerboard and ended where contrast changed away from the background value. The perceived apparent motion was not attributable to either postrectification motion-energy analysis or salience-mapping/feature-tracking mechanisms. Parallel results for 1st-order, luminance-defined motion (H. S. Hock, L. A. Gilroy, & G. Harnett, 2002) suggest that counter-changing activation provides a common basis for the perception of both luminance- and texture-contrast-defined apparent motion.