The Chrysippus intuition and contextual theories of truth

Contextual theories of truth are motivated primarily by the resolution they provide to paradoxical reasoning about truth. The principal argument for contextual theories of truth relies on a key intuition about the truth value of the proposition expressed by a particular utterance made during paradoxical reasoning, which Anil Gupta calls “the Chrysippus intuition.” In this paper, I argue that the principal argument for contextual theories of truth is circular, and that the Chrysippus intuition is false. I conclude that the philosophical motivation for contextual theories of truth fails.

A Common Genetic Factor Explains the Covariation Among ADHD ODD and CD Symptoms in 9–10 Year Old Boys and Girls

Previous studies examining the covariation among Attention Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD) and Conduct Disorder (CD) have yielded inconsistent results. Some studies have concluded that the covariation among these symptoms is due to common genetic influences, whereas others have found a common environmental overlap. The present study investigated the genetic and environmental correlations among these three childhood disorders, based on a sample of 1,219 twins, age 9–10 years. A latent externalizing behavior factor was found to explain the covariance among ADHD, ODD and CD symptoms. Genetic influences explained more than half of the variance in this externalizing factor in both boys and girls. There were also unique genetic and environmental influences in each set of symptoms, suggesting some etiological independence of the three disorders. Our findings have implications for molecular genetic studies trying to identify susceptibility genes for these disorders. This study was funded by NIMH (R01 MH58354). Catherine Tuvblad was supported by post-doctoral stipends from the Swedish Council for Working Life and Social Research (Project 2006-1501) and the Sweden-America Foundation. Adrian Raine was supported by NIMH (Independent Scientist Award K02 MH01114-08). We thank the Southern California Twin Project staff for their assistance in collecting data, and the twins and their families for their participation.     

Genetic and environmental transactions underlying educational attainment

This report used a population-representative longitudinal twin study with two birth cohorts to explore the association between intelligence and education by understanding how genetic and environmental influences on intelligence moderate genetic and environmental influences on school grades and educational attainment. Nonshared environmental influences on grades were strong when IQ was low, but decreased across the range of IQ. Shared environmental influences common to age 24 educational attainment and age 17 IQ were strong when IQ was low, but genetic influences common to IQ and education were strong when IQ was high. These results suggest that the causal mechanisms linking educational variables with intelligence differ for people with different levels of intelligence.     

Pentylenetetrazole as an unconditioned stimulus for olfactory and contextual fear conditioning in rats

The association of five footshocks with a neutral odor is able to establish an olfactory fear conditioning in rats. The present study sought to investigate whether the systemic administration of pentylenetetrazole (PTZ; 3.75–15 mg/kg) would turn the coffee odor in a conditioned stimulus in the fear conditioning paradigm. The results showed that rats started to display risk assessment and avoidance after PTZ (15 mg/kg)–coffee odor pairing. When three mild footshocks (0.4 mA for 2 s) were delivered during this pairing, the conditioned response exhibited was greater than before. In both cases, however, pretreatment with the benzodiazepine midazolam (MDZ. 0.5 mg/kg i.p.) fully counteracted the expression of these defensive behaviors. Moreover, after being paired with 15 mg/kg of PTZ alone or combined with footshocks, the coffee odor was able to promote a new fear conditioning related to the context where it was re-exposed. The present findings point out the usefulness of PTZ as an unconditioned stimulus to promote fear conditioning to olfactory and contextual cues in rats.     

Survey of New Zealand truck driver fatigue and fitness for duty

This paper presents recent research into compliance with current driving hours regulations, the effectiveness of using driving hours to predict fatigue, and alternative compliance and enforcement options. The paper describes results of a major survey of truck driver fatigue in New Zealand, a review of international compliance and enforcement procedures, and research focussing on the social forces and influences that affect truck drivers. The survey of truck drivers was based on interviews and performance tests collected from 600 truck drivers at depots, wharves, markets, and other locations throughout the North Island of New Zealand. The interviews included: questions on driver demographic and work/rest patterns, drivers' attitudes towards fatigue, propensity towards daytime sleepiness, and a self-assessment of the driver's momentary level of fatigue. In addition, a simulator-based performance test of driving was undertaken. The performance test included a combination of a standard driving task, a dual-axis sub-critical tracking task (maintaining speed and steering in a controlled but unstable environment, a virtual roadway affected by the appearance of random wind gusts requiring steering correction), and a tertiary or side-task requiring driver monitoring and periodic responses. The initial results from the first 100 drivers have found a sizable number of drivers exceeding the allowable driving hours, high levels of fatigue and sleepiness, and interesting differences between line-haul and local delivery drivers. A related research project into the social processes and relationships that affect truck drivers has resulted in a good understanding of the social conditions that influence cultural change and the actions of truck drivers and fleet managers. In this paper we will have particular regard to these processes in the construction of ideas concerning safety. This includes an understanding of the role of major stakeholders, such as freight forwarders and the enforcement agencies with respect to drivers and their conditions, actions and understanding of the road transport industry. This knowledge coupled with the survey results and an understanding of compliance and enforcement alternatives will be used to explore potential fatigue management options.     

Contextual fear conditioning predicts subsequent avoidance behaviour in a virtual reality environment

Avoidance behaviour is a crucial component of fear and is importantly involved in the maintenance of anxiety disorders. Presumably, fear conditioning leads to avoidance of the feared object or context. A virtual reality contextual fear conditioning paradigm was used to investigate the association between explicit conditioning effects and subsequent avoidance behaviour. Mild electric shocks were administered in one context (anxiety context), but never in a second context (safety context). Subsequent avoidance behaviour was assessed by asking participants to choose two out of three contexts (a neutral context was added) to visit again. Participants avoided the anxiety context, but did not prefer the safety over the neutral context. Participants with substantial conditioning effects, as reflected in differential valence, arousal and anxiety ratings, avoided the anxiety context but not the safety context. In sum, we demonstrated an association between context conditioning effects on an explicit level and later avoidance behaviour.     

Learning Words Via Reading: Contextual Diversity,Spacing, and Retrieval Effects in Adults

We examined whether variations in contextual diversity, spacing, and retrieval practice influenced how well adults learned new words from reading experience. Eye movements were recorded as adults read novel words embedded in sentences. In the learning phase, unfamiliar words were presented either in the same sentence repeated four times (same context) or in four different sentences (diverse context). Spacing was manipulated by presenting the sentences under distributed or non‐distributed practice. After learning, half of the participants were asked to retrieve the new words, and half had an extra exposure to the new words. Although words experienced in diverse contexts were acquired more slowly during learning, they enjoyed a greater benefit of learning at immediate posttest. Distributed practice also slowed learning, but no benefit was observed at posttest. Although participants who had an extra exposure showed the greatest learning benefit overall, learning also benefited from retrieval opportunity, when words were experienced in diverse contexts. These findings demonstrate that variation in the content and structure of the learning environment impacts on word learning via reading.     

Internalization of the thin and muscular body ideal and disordered eating in adolescence: the mediation effects of body esteem

This study investigates body esteem factors (weight-esteem and appearance-esteem) as mediators of the relationship between ‘internalization of the ideal body figure’ and disordered eating behaviors (restrained, emotional and external eating) in a community sample of adolescent males (n = 810) and females (n = 1137) from the Ontario Research on Eating and Adolescent Lifestyles (REAL) study. Mediation models were examined using a bootstrapping approach to test indirect effects and indirect contrasts. In males, weight-esteem partially mediated the relationship between muscular ideal and restrained eating; appearance-esteem partially mediated effects in the emotional and external eating regressions. In females, both weight-esteem and appearance-esteem partially mediated the relationship between thin ideal and all three forms of disordered eating; weight-esteem was a stronger mediator for restrained eating, and appearance-esteem a stronger mediator for emotional and external eating. Body esteem is important to consider for prevention and treatment of disordered eating in both genders.     

Developmental changes in coping: Situational and methodological influences

Abstract

Previous studies on the development of coping have shown rather inconsistent findings regarding the developmental trajectories for different coping dimensions. The aim of this study is to search for possible influences that might explain these inconsistencies. The analysis focuses on methodological influences (longitudinal vs. cross-sectional assessments) and situational influences. Two samples of children were traced longitudinally with yearly assessments from grade 2 to 5 (sample 1, N =432) and from grade 4 to 7 (sample 2, N =366). A third sample (N =849) was added with cross-sectional assessments from grade 2 to 7. The assessed coping dimensions were related to (a) problem solving, (b) seeking social support, (c) palliative coping, (d) externalizing emotional coping, and (e) avoidant coping. The use of the coping strategies had to be assessed for six stress-evoking situations. The results show only small differences between the longitudinal and the cross-sectional coping assessments. There are, however, clear situational influences on the choice of the coping strategies and also on the resulting developmental trajectories.     

Contextual learning of multiple target locations in visual search

In visual search, detection of a target is faster when a layout of nontarget items is repeatedly encountered, suggesting that contextual invariances can guide attention. Moreover, contextual cueing can also adapt to environmental changes. For instance, when the target undergoes a predictable (i.e., learnable) location change, then contextual cueing remains effective even after the change, suggesting that a learned context is “remapped” and adjusted to novel requirements. Here, we explored the stability of contextual remapping: Four experiments demonstrated that target location changes are only effectively remapped when both the initial and the future target positions remain predictable across the entire experiment. Otherwise, contextual remapping fails. In sum, this pattern of results suggests that multiple, predictable target locations can be associated with a given repeated context, allowing the flexible adaptation of previously learned contingencies to novel task demands.