The purpose of this article was to review the findings from existing peer-reviewed experimental studies describing the behavioral and developmental outcomes associated with prenatal exposure to illicit drugs. Forty-six such studies and 460 individual outcomes occurring from birth to 60 months were identified. Only half of these outcomes (49.8%) were statistically significant, indicating adverse effects of prenatal exposure. The greatest number of outcomes were identified for infants younger than 1 month of age and within the neurodevelopmental domain. The contrast between these outcomes derived from experimental studies and those reported in the popular press is discussed.
Direct classroom observation: potential problems and solutions George Sideridis Direct observation has been the most widely used behavioural assessment method in education. The aim of this article is to define observer bias, drift and reactivity, using examples from the behaviour analytical literature, and suggest ways of controlling them. It concludes that the following recommendations can assist the reliable and accurate recording of student behaviour: (1) train observers intensively until they achieve high levels of reliability and accuracy, (2) use simple observational systems with as few behavioural categories as possible and simple operational definitions, (3) keep observers blind and experimenters double-blind to experimental conditions, subject characteristics, etc., (4) plan periodic training sessions for the observers to re-study the operational definition of behaviours and discuss the problems of the observation situation, (5) inform observers that all their observations are monitored, (6) use ‘real time’ observations and not time-sampling procedures, (7) keep observers motivated and reinforce them for accurate observation, and (8) have observers become part of the classroom environment beforehand.
In this study we sought to characterize developmental trajectories of EEG spectral power over the first 2 years after birth and examine whether family income or maternal education alter those trajectories. EEGs (n=161 infants, 534 EEGs) collected longitudinally between 2 and 24 months of age were analyzed. Absolute frontal power across 7 canonical frequency bands was calculated. For each frequency band, a piecewise growth curve model was fit, resulting in an estimated intercept and two slope parameters from 2–9 months and 9–24 months of age. Across 6/7 frequency bands, absolute power significantly increased over time, with steeper slopes in the 2–¬9 month period compared to 9–24 months. Increased family income, but not maternal education, was associated with higher intercept (2–3 month power) across delta–gamma bands (p range = 0.002 to 0.04), and reduced change in power between 2–9 months of age in lower frequency bands (delta-alpha, p range = 0.01-0.02). There was no significant effect of income on slope between 9–24 months. EEG intercept and slope measures did not mediate relationships between income and 24-month verbal and nonverbal development. These results emphasize the potential role of socioeconomic factors in shaping brain trajectories.
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