Contraction intensity and velocity on vastus lateralis SEMG power spectrum and amplitude

Effect of contraction intensity [100%, 75%, 50%, and 25% maximum voluntary contraction (MVC)] and movement velocity [0 degrees (isometric)], 50 degrees, 100 degrees, 200 degrees, and 400 degrees/sec. [isovelocities]) on root mean square amplitude (SEMG-RMS) and median frequency power spectrum (SEMG-MNF) of vastus lateralis (VL) surface electromyography was investigated with ten healthy female university students. Peak torque (PT), mean torque (MT), SEMG-MNF, and SEMG-RMS, analyzed using separate repeated-measures analyses of variance (p < or = .05), indicated: (1) an inverse relation between PT and MT and movement velocity, (2) greater SEMG-MNF values during all isovelocity conditions compared with isometric conditions, with highest values occurring at 50 degrees /sec. and at 100% and 75% MVC, and (3) at all contraction intensities SEMG-RMS values were higher during dynamic movements than isometric movements and highest at 200 degrees /sec. Isovelocity contractions were inferred to facilitate a greater recruitment of fast-twitch fibers (via increased SEMG-MNF), which was intensified at 50 degrees /sec., whereas greater overall muscle activation was found at 200 degrees /sec.     

Self-other rating agreement and leader-member exchange (LMX): a quasi-replication

Data from a sample of 83 elected community leaders and 391 direct-report staff (resulting in 333 useable leader-member dyads) were reanalyzed to test relations between self-other rating agreement of servant leadership and member-reported leader-member exchange (LMX). Polynomial regression analysis indicated that the self-other rating agreement model was not statistically significant. Instead, all of the variance in member-reported LMX was accounted for by the others' ratings component alone.     

Modified Frankfurt-type counterexamples and flickers of freedom

A great deal of attention has been paid recently to the claim that traditional Frankfurt-type counterexamples to the Principle of Alternative Possibilities (PAP), which depend for their success on the presence of a perfectly reliable indicator (or prior sign) of what an agent will freely do if left to act on his own, are guilty of begging the question against incompatibilists, since such indicators seem to presuppose a deterministic relation between an agent’s free action and its causal antecedents. Objections of this sort have given rise to considerable efforts to construct alternative Frankfurt-type counterexamples that do not rely on prior signs of this kind and so do not presuppose determinism in a way that incompatibilists should find objectionable. One consequence of this shift in the way Frankfurt-type counterexamples are formulated is that it provides an opportunity for the forceful resurgence of certain versions of the so-called flicker defense of PAP. In this paper I develop two versions of the flicker defense, indicate their advantages over other versions of this strategy, and defend them against objections. Insofar as either of these is successful, it will show not only that PAP has yet to be falsified by any of the modified Frankfurt-type counterexamples currently on offer but that cases of this sort are in principle incapable of falsifying PAP.     

Rationality and indeterminate probabilities

We argue that indeterminate probabilities are not only rationally permissible for a Bayesian agent, but they may even be rationally required. Our first argument begins by assuming a version of interpretivism: your mental state is the set of probability and utility functions that rationalize your behavioral dispositions as well as possible. This set may consist of multiple probability functions. Then according to interpretivism, this makes it the case that your credal state is indeterminate. Our second argument begins with our describing a world that plausibly has indeterminate chances. Rationality requires a certain alignment of your credences with corresponding hypotheses about the chances. Thus, if you hypothesize the chances to be indeterminate, your will inherit their indeterminacy in your corresponding credences. Our third argument is motivated by a dilemma. Epistemic rationality requires you to stay open-minded about contingent matters about which your evidence has not definitively legislated. Practical rationality requires you to be able to act decisively at least sometimes. These requirements can conflict with each other-for thanks to your open-mindedness, some of your options may have undefined expected utility, and if you are choosing among them, decision theory has no advice to give you. Such an option is playing Nover and Hájek??s Pasadena Game, and indeed any option for which there is a positive probability of playing the Pasadena Game. You can serve both masters, epistemic rationality and practical rationality, with an indeterminate credence to the prospect of playing the Pasadena game. You serve epistemic rationality by making your upper probability positive-it ensures that you are open-minded. You serve practical rationality by making your lower probability 0-it provides guidance to your decision-making. No sharp credence could do both.     

Two experimental tests of trust in in‐group strangers: The moderating role of common knowledge of group membership

The role that shared group membership plays in decisions to trust others is now well established within social psychology. A close reading of this literature, however, shows that this process is often moderated by other variables. Currently, we examined one potential moderator of this process. In particular, we evaluated the role that common knowledge of a shared social group membership between self and a to‐be‐trusted stranger provides as a basis for trusting this stranger. This common knowledge emerges when the truster knows the group membership of the to‐be‐trusted other, and believes that this other also knows the group membership of the truster. In two experiments, using pre‐existing and minimal groups, we show that people are more likely to trust an in‐group member over an out‐group member under conditions of common group‐membership knowledge rather than private group‐membership knowledge (i.e. other does not know truster's group), even when they could choose not to trust anyone. The manner in which these data add to current understandings of group‐based trust in strangers is discussed. Copyright © 2011 John Wiley & Sons, Ltd.     

Reducing stereotype threat in order to facilitate learning

Recent stereotype threat research has demonstrated that negative stereotypes about women's math ability can impair their mathematical learning. This experiment extends this research by examining whether presenting “gender fair” information can reduce learning decrements (on a focal and transfer task) and if the timing of this information matters. Women (N = 140) and men (N = 60) were randomly assigned to one of four conditions: control, stereotype threat only, stereotype threat removed before learning, and stereotype threat removed after learning. Compared with women in the control condition and women who had stereotype threat removed before learning, learning and transfer were poorer for women in the stereotype threat only condition and women who had stereotype threat removed after learning but before learning assessment. Men's learning and transfer were unaffected by condition. These findings suggest that a manipulation that can reduce performance deficits can also reduce learning decrements if it is presented before learning occurs. Copyright © 2011 John Wiley & Sons, Ltd.     

The next generation: the value of reminding

In two experiments, we investigated the influence of repeated processing in the context of the generation effect. In both experiments, participants studied words once or twice. Once-studied words either were read or were generated from a definition. Twice-studied words were read both times, generated both times, or read once and generated once. Free recall was best (in order of decreasing performance) after generating twice, after generating plus reading, and finally after generating once; any generation was better than purely reading. Recognition showed a similar pattern, except that the benefit of generating twice was not as striking as in recall and that reading plus generating was just as effective as generating twice. The overall pattern of results is accounted for by a simple model in which a second encoding results in a reminding of the first encoding, and this additional encoding supports subsequent recollection. This reminding is, consequently, more effective in recall than in recognition, and it operates in accordance with the principles of transfer-appropriate processing.     

Variations in constrained retrieval

Mentally reinstating encoding operations at retrieval might improve access to memories; however, such constrained retrieval is an effortful process that may not always be used. The memory-for-foils procedure (Jacoby, Shimizu, Daniels, & Rhodes, Psychonomic Bulletin & Review 12, 852-857, 2005) infers participant-initiated mental reinstatement of encoding operations during attempts at recognition from the differential memory that accrues to foils during a test of deeply processed items versus during a test of shallowly processed items, as indicated by performance on a final recognition memory test for the foils. Experiment 1 tested whether differential memory for foils is due to the evocation of task context during recollection of neighboring old items. Experiment 2 tested whether inducing a set to respond without much effort on a prior recognition test affects the likelihood of constrained retrieval on later tests. Experiment 3 tested whether constrained retrieval is less likely to occur when the deep versus shallow source of test items is intermixed, rather than blocked in separate tests. These experiments provide evidence that people query memory by mentally reinstating encoding operations and identify conditions that affect the probability of constrained retrieval.     

Multi-wave Prospective Examination of the Stress-Reactivity Extension of Response Styles Theory of Depression in High-Risk Children and Early Adolescents

The current study tested the stress-reactivity extension of response styles theory of depression (Nolen-Hoeksema Journal of Abnormal Psychology 100:569–582, 1991) in a sample of high-risk children and early adolescents from a vulnerability-stress perspective using a multi-wave longitudinal design. In addition, we examined whether obtained results varied as a function of either age or sex. During an initial assessment, 56 high-risk children (offspring of depressed parents; ages 7–14) completed measures assessing rumination and depressive symptoms. Children were subsequently given a handheld personal computer which signalled them to complete measures assessing depressive symptoms and negative events at six randomly selected times over an 8-week follow-up interval. In line with hypotheses, higher levels of rumination were associated with prospective elevations in depressive symptoms following the occurrence of negative events. Sex, but not age, moderated this association. Rumination was more strongly associated with elevations in depressive symptoms following the occurrence of negative events in girls than in boys.     

Improving Working Memory in Children with Attention-Deficit/Hyperactivity Disorder: The Separate and Combined Effects of Incentives and Stimulant Medication

Working memory (WM) is considered a core deficit in Attention-Deficit/ Hyperactivity Disorder (ADHD), with numerous studies demonstrating impaired WM among children with ADHD. We tested the degree to which WM in children with ADHD was improved by performance-based incentives, an analog of behavioral intervention. In two studies, WM performance was assessed using a visuo-spatial n-back task. Study 1 compared children (ages 9-12?years) with ADHD-Combined type (n?=?24) to a group of typically developing (TD) children (n?=?32). Study 1 replicated WM deficits among children with ADHD. Incentives improved WM, particularly among children with ADHD. The provision of incentives reduced the ADHD-control group difference by approximately half but did not normalize WM. Study 2 examined the separate and combined effects of incentives and stimulant medication among 17 children with ADHD-Combined type. Both incentives and a moderate dose of long-acting methylphenidate (MPH; ~0.3?mg/kg t.i.d. equivalent) robustly improved WM relative to the no-incentive, placebo condition. The combination of incentives and medication improved WM significantly more than either incentives or MPH alone. These studies indicate that contingencies markedly improve WM among children with ADHD-Combined type, with effect sizes comparable to a moderate dose of stimulant medication. More broadly, this work calls attention to the role of motivation in studying cognitive deficits in ADHD and in testing multifactorial models of ADHD.