Marijuana use from adolescence to young adulthood: multiple developmental trajectories and their associated outcomes.

This study used latent growth mixture modeling to identify discrete developmental patterns of marijuana use from early adolescence (age 13) to young adulthood (age 23) among a sample of 5,833 individuals. After the a priori removal of abstainers, 4 trajectory groups were identified: early high users, who decreased from a relatively high level of use at age 13 to a more moderate level: stable light users, who maintained a low level of use: steady increasers, who consistently increased use; and occasional light users, who began use at age 14 and used at low levels thereafter. Analyses of covariance comparing the trajectory groups on behavioral, socioeconomic, and health outcomes at age 29 revealed that abstainers consistently had the most favorable outcomes, whereas early high users consistently had the least favorable outcomes.     

Emotions in reading: Disgust, empathy and the contextual learning hypothesis

Emotion effects in reading have typically been investigated by manipulating words' emotional valence and arousal in lexical decision. The standard finding is that valence and arousal can have both facilitatory and inhibitory effects, which is hard to reconcile with current theories of emotion processing in reading. Here, we contrasted these theories with the contextual-learning hypothesis, according to which, sensitivity to a specific emotion - disgust in the present study - rather than valence or arousal affects lexical decision performance. Participants were divided into two groups (high versus low disgust sensitivity). Results showed that participants with high disgust sensitivity showed an inhibitory effect, whereas participants with low-disgust sensitivity showed a facilitatory effect. Individual differences in lexical decision performance were predicted by disgust sensitivity but not valence, arousal, or general emotion sensitivity. These findings highlight the need to focus on individual differences both in studies and theories of emotion processing in reading.     

Openness, fluid intelligence, and crystallized intelligence: Toward an integrative model

Many studies are concerned with the bivariate relationships between Openness, fluid intelligence (Gf), and crystallized intelligence (Gc). Results suggest an influence of Gf and Openness on Gc. However, the overlap between Gf and Openness is rarely controlled for. Moreover, interaction effects or longitudinal influences are also often neglected. The present two studies aimed to elucidate exactly these interactions and longitudinal influences. Besides a main effect of Gf on Gc, Study 1 (N = 180) revealed an interaction effect between Openness and Gf. Study 2 utilized longitudinal data (N = 172) and identified an effect of Openness on the development of Gf. Gf and Openness predicted Gc 6 years later. A model integrating the results and providing a theoretical framework and outlook is proposed.