There are at least two kinds of probability matching: evidence from a secondary task

Probability matching is a suboptimal behavior that often plagues human decision-making in simple repeated choice tasks. Despite decades of research, recent studies cannot find agreement on what choice strategies lead to probability matching. We propose a solution, showing that two distinct local choice strategies—which make different demands on executive resources—both result in probability-matching behavior on a global level. By placing participants in a simple binary prediction task under dual- versus single-task conditions, we find that individuals with compromised executive resources are driven away from a one-trial-back strategy (utilized by participants with intact executive resources) and towards a strategy that integrates a longer window of past outcomes into the current prediction. Crucially, both groups of participants exhibited probability-matching behavior to the same extent at a global level of analysis. We suggest that these two forms of probability matching are byproducts of the operation of explicit versus implicit systems.     

Time to task failure of trunk extensor muscles differs with load type

Time to task failure of trunk extensor muscles during seated submaximal isometric exertions was assessed in 18 healthy participants using 2 different load types. One required supporting an inertial load (position-matching task) whereas the 2nd required maintaining an equivalent torque against a rigid restraint (force-matching task). Time to task failure was significantly longer for position-matching tasks compared to the force-matching tasks. This finding is opposite to that reported for the appendicular muscles. A subset of 4 individuals completed a 2nd experiment to test the time to task failure of the elbow flexors in the position- and force-matching tasks. Time to task failure of the elbow flexors was significantly longer for the force-matching tasks compared to position matching. Thus, the same population shows that the effects of load type on time to task failure are opposite for the appendicular and axial muscles. This could be an important issue in understanding the mechanisms of task failure, and the endurance capacity of the trunk extensor muscles.     

Dennett’s deism

To suggest that Daniel Dennett is a deist is to invite ridicule. Dennett is both an avowed atheist and defender of naturalism in philosophy. Yet if we pay heed to the entirety of Dennett’s claims a curious picture emerges. My suggestion is that Hegel and Marx represent the rival responses to what we might call the modern predicament: what is the nature of existence in a world which seems a mechanism? Dennett’s response to this question is Hegelian, and involves a commitment to a religiosity which might surprise those otherwise receptive to his arguments.     

On the Ternary Relation and Conditionality

One of the most dominant approaches to semantics for relevant (and many paraconsistent) logics is the Routley?CMeyer semantics involving a ternary relation on points. To some (many?), this ternary relation has seemed like a technical trick devoid of an intuitively appealing philosophical story that connects it up with conditionality in general. In this paper, we respond to this worry by providing three different philosophical accounts of the ternary relation that correspond to three conceptions of conditionality. We close by briefly discussing a general conception of conditionality that may unify the three given conceptions.     

The erosive effects of racism: reduced self-control mediates the relation between perceived racial discrimination and substance use in African American adolescents

Perceived racial discrimination, self-control, anger, and either substance use or use cognitions were assessed in 2 studies conducted with samples of African American adolescents. The primary goal was to examine the relation between discrimination and self-control over time; a 2nd goal was to determine whether that relation mediates the link between discrimination and substance use found in previous research. Study 1, which included a latent growth curve analysis with 3 waves of data, indicated that experience with discrimination (from age 10 years to age 18 years) was associated with reduced self-control, which then predicted increased substance use. Additional analyses indicated anger was also a mediator of this discrimination to use relation. Study 2, which was experimental, showed that envisioning an experience involving discrimination was associated with an increase in substance-related responses to double entendre words (e.g., pot, roach) in a word association task, especially for participants who were low in dispositional self-control. The effect was again mediated by reports of anger. Thus, the "double mediation" pattern was discrimination → more anger and reduced self-control → increased substance use and/or substance cognitions. Results are discussed in terms of the long-term impact of discrimination on self-control and health behavior. Implications for interventions aimed at ameliorating the negative effects of discrimination and low self-control on health are also discussed.     

The Influence of Families on Early Adolescent School Connectedness: Evidence That This Association Varies with Adolescent Involvement in Peer Drinking Networks

School connectedness is central to the long term well-being of adolescents, and high quality parent–child relationships facilitate school connectedness. This study examined the extent to which family relationship quality is associated with the school connectedness of pre- and early teenagers, and how this association varies with adolescent involvement in peer drinking networks. The sample consisted of 7,372 10–14 year olds recruited from 231 schools in 30 Australian communities. Participants completed the Communities that Care youth survey. A multi-level model of school connectedness was used, with a random term for school-level variation. Key independent variables included family relationship quality, peer drinking networks, and school grade. Control variables included child gender, sensation seeking, depression, child alcohol use, parent education, and language spoken at home. For grade 6 students, the association of family relationship quality and school connectedness was lower when peer drinking networks were present, and this effect was nonsignificant for older (grade 8) students. Post hoc analyses indicated that the effect for family relationship quality on school connectedness was nonsignificant when adolescents in grade 6 reported that the majority of friends consumed alcohol. The results point to the importance of family-school partnerships in early intervention and prevention.     

Maternal parenting stress and mothers' reports of their infants' mastery motivation

Mastery motivation is a psychological force that stimulates an individual to attempt to master a task that is challenging to him or her. This prospective longitudinal study examined the relationship between maternal stress, using the Parenting Stress Index-Short Form, and infant mastery motivation, using the Dimensions of Mastery Questionnaire, for 150 mother-infant pairs assessed at both 6- and 18-months of age. Infants of mothers with elevated stress levels at 6 months tended to show lower mastery motivation at 18 months (standardized beta=-.46, p=.001). Conversely, infants with lower general competence (standardized beta=-.24, p=.021) and lower persistence during social interactions with other children (standardized beta=-.18, p=.037) at 6 months of age had mothers with elevated total stress at 18 months of age. Implications for programs which simultaneously intervene with child and mother are discussed.     

Examining the convergent validity of shared mental model measures

Despite widespread interest in shared mental models (SMMs) within teams and groups and an extensive empirical literature examining SMM?Cperformance links, very little is known about the convergent validity of commonly used measures of SMMs. In this study, two-person teams (n = 96) engaged in a complex flight task and completed three SMM measures: concept mapping, paired ratings, and causal mapping. Task-based sharedness scores were compared across the measures. Analyses were conducted in two ways: using SMMs of actual team members (n = 96 pairs) and using the SMMs of pairs of participants who worked separately but for whom similarity indices were calculated after the study (n = 18,240). The purpose of the latter pairs, coined pseudo-partners, was to create a sample with considerable power to test the convergent validity of the SMM measures. The results call into some question the convergent validity of these task-based SMM measures.     

The role of the magnocellular visual pathway in the attentional blink

Visual attention has temporal limitations. In the attentional blink (AB) a stream of stimuli such as letters or digits are presented to a participant on a computer monitor at a rapid rate. Embedded in the stream are two targets that the participant must try to identify. Identification of the second target is severely impaired if it is presented within approximately 500ms of the first target. This is the 'blink' in visual attention. In this study we examined the role of the magnocellular visual pathway in the AB. This fast conducting pathway has high temporal resolution and contrast sensitivity. It is also insensitive to the direction of chromatic contrast, and this attribute was exploited in order to isolate its contributions to temporal attention. Colour defined, luminance noise masked AB streams were compared to AB streams of varying achromatic contrast. The four observers, (2F and 2M) aged between 21 and 35years, had normal visual acuity and colour vision. The colour stimuli produced a similar blink to the moderate contrast achromatic stimuli. This indicates that the magnocellular pathway does not have a privileged role in the attentional blink. We provide an explanation of previous apparently contradictory findings in terms of the role of different types of visual masking in the attentional blink.     

Coping with racial discrimination: The role of substance use

Three studies tested the hypothesis that the relation between perceived racial discrimination and substance use reported in previous research is moderated by use of substances as a coping mechanism. Studies 1 and 2 were experimental studies of African American adolescents' and young adults' reactions to a discrimination experience. Results revealed that those who endorsed substance use-as-coping reported more willingness to use substances after experiencing discrimination. Study 3 was a prospective study of the relation between perceived discrimination and substance use over an 8-year period in African American adolescents. Results demonstrated that discrimination is associated with increases in substance use, but only among adolescents who endorse substance use-as-coping. Together, these three studies provide evidence that experiencing discrimination has both short- and long-term detrimental effects on African Americans' substance use, but significantly more so for those who adopt a pattern of using substances as a coping mechanism. (PsycINFO Database Record (c) 2012 APA, all rights reserved).