Marijuana effects on human forgetting functions

It has long been known that acute marijuana administration impairs working memory (e.g., the discrimination of stimuli separated by a delay). The determination of which of the individual components of memory are altered by marijuana is an unresolved problem. Previous human studies did not use test protocols that allowed for the determination of delay-independent (initial discrimination) from delay-dependent (forgetting or retrieval) components of memory. Using methods developed in the experimental analysis of behavior and signal detection theory, we tested the acute effects of smoked marijuana on forgetting functions in 5 humans. Immediately after smoking placebo, a low dose, or a high dose of marijuana (varying in delta9-THC content), subjects completed delayed match-to-sample testing that included a range of retention intervals within each test session (0.5, 4, 12, and 24 s). Performances (discriminability) at each dose were plotted as forgetting functions, as described and developed by White and colleagues (White, 1985; White & Ruske, 2002). For all 5 subjects, both delta9-THC doses impaired delay-dependent discrimination but not delay-independent discrimination. The outcome is consistent with current nonhuman studies examining the role of the cannabinoid system on delayed matching procedures, and the data help illuminate one behavioral mechanism through which marijuana alters memory performance.     

Discovering New Ways of Moving: Observational Analysis of Motor Creativity While Dancing Contact Improvisation and the Influence of the Partner

Contact improvisation (CI) is a form of dance based on motor creativity, improvisation and the physical contact between different improvisers dancing together. This will generate different ways of moving and a varied use of motor creativity depending on the dancers involved. This study aims to observe the differences in movement generation depending on the partner by using OSMOS (Observational System of Motor Skills; Castañer & Camerino 2006; Castañer et al., 2009). Four contact improvisers were video‐recorded while dancing in duets. Data were analysed by three observers using Theme Coder software (Magnusson, 1996) for the detection of T‐patterns and the production of event frequency charts. The results show that (1) the motor skills that appear most frequently are the conduction of partners, elevations, spatial level changes and turns; (2) motor creativity is affected by the partner, as there is a reciprocal influence in the dance; and (3) motor creativity is enhanced by interaction with a partner.     

Human proactive aggression: association with personality disorders and psychopathy

Aggressive behaviors can be divided into two categories: reactive and proactive. Reactive aggressive behaviors occur in response to a stimulus or provocation. Proactive aggressive behaviors occur without provocation and are goal directed. A number of findings have suggested that individuals displaying proactive aggression may be discerned from individuals not displaying proactive aggression on measures of personality, psychopathology and psychopathy as well as in aggressive histories and type and severity of aggressive behaviors committed. In this study, subjects were recruited from a large urban community and classified as proactive (n = 20), reactive-only (n = 20) or nonaggressive (n = 10) based on laboratory behavioral testing. Subjects were administered a battery of questionnaires and structured interviews pertaining to personality disorders and psychopathy. It was hypothesized that proactive aggressive subjects would show greater numbers of personality disorders and have greater psychopathy relative to reactive-only and nonaggressive subjects. These hypotheses were supported. These results suggest that proactive aggression may be identified in a laboratory-based task, and differences between proactive and reactive-only aggressors can be detected.