Effects of varying trial distribution,intra- and extramaze cues,and amount of reward on proactive interference in the radial maze

Rats are typically less accurate in their arm selections in the radial maze over successive trials in a session (Roberts & Dale, 1981). In the present study, rats’ choice accuracy declined when such trials were separated by 2-min (massed) but not by 2-h (spaced) intertriai intervals. Changing intramaze visual/tactile arm stimuli (Experiments 1 and 3) or extramaze landmark stimuli (Experiment 4) between trials weakened the massed-trials effect, but changing the number of food pellets per arm, either alone or in conjunction with changes in intramaze cues (Experiments 2 and 3), did not. The rats also tended to avoid the spatial locations of their last four choices on a previous trial during their first four choices on a current trial, and more so with massed than with spaced trials. These findings indicate that intertriai proactive interference (PI) occurred only with massed trials and was weakened by changing intra- and extramaze cues between such trials.     

Academic Follow-Up Data on Two Cohorts of High-Risk Transfer Children

Two cohorts of children from inner-city elementary schools were provided a tutoring intervention to help in their transition to new schools. Participants were third, fourth, and fifth grade children who were identified as having low-income status, evidencing lags on achievement tests, and experiencing stressful life events. The intervention involved an orientation program with twice weekly paraprofessional tutoring. Two and three year academic and sociometric follow-up data were collected. Those provided the intervention evidenced some improvements over time, and these changes were most prominent in the area of reading grades. Fewer significant findings were found on sociometric indices.     

Mild head injury as a source of developmental disabilities.

The hospital-reported incidence of mild head injury among children indicates a prevalence of 2% to 3% in high-school-aged adolescents (14 to 18 years). Yet, our survey of 616 high school adolescents suggests that light and mild head injury (not necessarily leading to hospital admission) is almost 10 times this level. Despite the common notion that such injury is generally benign, we found significant relationships in our sample between reported head injury and hyperactivity, stuttering, mixed handedness, and dislike of mathematics.