Development of the coordination between posture and manual control

Studies have suggested that proper postural control is essential for the development of reaching. However, little research has examined the development of the coordination between posture and manual control throughout childhood. We investigated the coordination between posture and manual control in children (7- and 10-year-olds) and adults during a precision fitting task as task constraints became more difficult. Participants fit a block through an opening as arm kinematics, trunk kinematics, and center of pressure data were collected. During the fitting task, the precision, postural, and visual constraints of the task were manipulated. Young children adopted a strategy where they first move their trunk toward the opening and then stabilize their trunk (freeze degrees of freedom) as the precision manual task is being performed. In contrast, adults and older children make compensatory trunk movements as the task is being performed. The 10-year-olds were similar to adults under the less constrained task conditions, but they resembled the 7-year-olds under the more challenging tasks. The ability to either suppress or allow postural fluctuations based on the constraints of a suprapostural task begins to develop at around 10 years of age. This ability, once developed, allows children to learn specific segmental movements required to complete a task within an environmental context.     

Identification with the retail organization and customer-perceived employee similarity: Effects on customer spending

Two constructs important to academicians and managers are the degree to which employees and customers identify with an organization, employee organizational identification (employee OI) and customer-company identification (customer identification), respectively. This research examines the effects of these identification constructs and the related construct of customer perceived similarity to employees on customer spending. Via a 1-year multilevel study of 12,047 customers and 1,464 store employees (sales associates) covering 212 stores of a specialty apparel retailer, our study contributes to the literature in 2 critical ways. First, we expand the theoretical network of employee OI and customer identification by examining the related construct of a customer's perceived similarity to store employees. We examine the incremental (not fully mediated) main and interaction effects of customer-perceived similarity to employees and employee OI on customer spending. Second, we examine the effect of customer identification on customer spending relative to the effect of customer satisfaction on customer spending. Thus, our study also contributes by demonstrating a potential complementary route to achieve customer spending (customer identification), a route that may be more readily affected by management than the efforts required for a sustained increase in customer satisfaction. Implications for academics and managers are offered. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

A method to monitor upper limb movement direction encoding in the corticomotor pathway

ABSTRACT Abnormal shoulder and elbow muscle coactivation patterns, or muscle synergies, are commonly present following stroke and may arise through dysfunctional descending neural control from the cortex. The authors evaluated a novel technique for examining corticomotor movement encoding of the upper limb in three dimensions. A 6-degree-of-freedom loadcell recorded arm twitch responses in healthy adults following stimulation over the cortex or over Erb's point in the periphery. Stimuli were delivered while the arm generated a 5 N preload in each of the 6 axial directions. The initial force twitch response to stimulation was used to construct twitch direction vectors for each preload direction. General linear mixed model analyses were used to determine the influence of stimulation location, preload direction, posture, and stimulation intensity on twitch direction. Cortical stimulation gave rise to arm twitch responses that were predictably modified by preload direction. Peripheral stimulation elicited stereotypical twitches that were not influenced by preload. Our stimulation, recording, and analysis techniques were able to capture movement encoding of the upper limb in three dimensions. Such techniques could be utilized in the stroke population to determine and monitor the presence of upper limb synergies during muscle activation.     

Motor deficits associated with mild, chronic hyponatremia: a factor analytic study

ABSTRACT Chronic hyponatremia (CHN) has traditionally been considered asymptomatic. If symptoms are observed, they are often mistakenly attributed to the underlying disorder. However, in recent studies neuropsychological deficits have been associated with CHN. The authors sought to determine the association between CHN and motor deficits. They used previously collected data, and 41 subjects with hyponatremia were included. An exploratory factor analysis with principal component analysis (PCA) was performed (eigenvalues >1.0). Factor scores were generated for each subject based on the resultant PCA factor structure. Finally, partial correlations were computed to measure the degree of association between baseline serum sodium concentration [Na+] and individual neuropsychological factor scores with the effect of age removed. All significance tests were performed using 2-tailed comparisons with alpha level of p ≤ .05. A 3-factor model emerged accounting for 70.17% of the total variance, including 1 factor that loaded primarily with motor speed and reaction time. A significant correlation was observed between this motor factor and serum [Na+] (r = -.477, p = .002). These findings add to previous observations suggesting that CHN is associated with subtle yet harmful motor deficits.     

Obtaining separate measures for implicit and explicit memory

In this paper a new model, the Implicit/Explicit Separation (IES) model, is developed and applied. The model is designed to obtain separate probability measures for explicit memory storage, implicit memory storage, fractional storage, and non-storage. The model is needed because memory research has shown the importance of the distinction between a conscious memory of a target event and a memory residue that is unable to support conscious recall or confident recognition, but it is still able to support guessing at rates above chance. Maximum likelihood and population-parameter mapping estimates for the parameters of the IES model are provided. The accuracy of parameter estimates is studied as a function of sample size. Three experiments are reported to demonstrate how the IES model is used to achieve a more fine grained assessment of the quality of information storage. These experiments also provide strong validation support for the IES model itself. Across the three experiments, each of the four components for representing target information (explicit, implicit, fractional, and non-storage) demonstrates a different pattern. The IES model is discussed in terms of alternative models such as the dual-process model and the process-dissociation model.     

Putting the brakes on aggression toward a romantic partner: the inhibitory influence of relationship commitment

Why do people behave aggressively toward romantic partners, and what can put the brakes on this aggression? Provocation robustly predicts aggression in both intimate and nonintimate relationships. Four methodologically diverse studies tested the hypothesis that provocation severity and relationship commitment interact to predict aggression toward one's romantic partner, with the aggression-promoting effects of provocation diminishing as relationship commitment increases. Across all four studies, commitment to one's romantic relationship inhibited aggression toward one's partner when individuals were severely (but not mildly) provoked. Study 4 tested the hypothesis that this Partner Provocation × Commitment interaction effect would be strong among individuals high in dispositional tendencies toward retaliation but weak (perhaps even nonexistent) among individuals low in such tendencies. Discussion emphasizes the importance of understanding instigating, impelling, and inhibiting processes in the perpetration of aggression toward intimate partners.     

Consequence Mining

The standard semantic definition of consequence with respect to a selected set X of symbols, in terms of truth preservation under replacement (Bolzano) or reinterpretation (Tarski) of symbols outside X, yields a function mapping X to a consequence relation \(\Rightarrow_X\). We investigate a function going in the other direction, thus extracting the constants of a given consequence relation, and we show that this function (a) retrieves the usual logical constants from the usual logical consequence relations, and (b) is an inverse to—more precisely, forms a Galois connection with—the Bolzano–Tarski function.     

Real Analysis in Paraconsistent Logic

This paper begins an analysis of the real line using an inconsistency-tolerant (paraconsistent) logic. We show that basic field and compactness properties hold, by way of novel proofs that make no use of consistency-reliant inferences; some techniques from constructive analysis are used instead. While no inconsistencies are found in the algebraic operations on the real number field, prospects for other non-trivializing contradictions are left open.     

Intuitionistic Epistemic Logic,Kripke Models and Fitch’s Paradox

The present work is motivated by two questions. (1) What should an intuitionistic epistemic logic look like? (2) How should one interpret the knowledge operator in a Kripke-model for it? In what follows we outline an answer to (2) and give a model-theoretic definition of the operator K. This will shed some light also on (1), since it turns out that K, defined as we do, fulfills the properties of a necessity operator for a normal modal logic. The interest of our construction also lies in a better insight into the intuitionistic solution to Fitch’s paradox, which is discussed in the third section. In particular we examine, in the light of our definition, DeVidi and Solomon’s proposal of formulating the verification thesis as \(\phi \rightarrow \neg \neg K\phi\). We show, as our main result, that this definition excapes the paradox, though it is validated only under restrictive conditions on the models.