Determinants of Scanpath Regularity in Reading

Scanpaths have played an important role in classic research on reading behavior. Nevertheless, they have largely been neglected in later research perhaps due to a lack of suitable analytical tools. Recently, von der Malsburg and Vasishth (2011) proposed a new measure for quantifying differences between scanpaths and demonstrated that this measure can recover effects that were missed with the traditional eyetracking measures. However, the sentences used in that study were difficult to process and scanpath effects accordingly strong. The purpose of the present study was to test the validity, sensitivity, and scope of applicability of the scanpath measure, using simple sentences that are typically read from left to right. We derived predictions for the regularity of scanpaths from the literature on oculomotor control, sentence processing, and cognitive aging and tested these predictions using the scanpath measure and a large database of eye movements. All predictions were confirmed: Sentences with short words and syntactically more difficult sentences elicited more irregular scanpaths. Also, older readers produced more irregular scanpaths than younger readers. In addition, we found an effect that was not reported earlier: Syntax had a smaller influence on the eye movements of older readers than on those of young readers. We discuss this interaction of syntactic parsing cost with age in terms of shifts in processing strategies and a decline of executive control as readers age. Overall, our results demonstrate the validity and sensitivity of the scanpath measure and thus establish it as a productive and versatile tool for reading research.     

The effect of force-controlled biting on human posture control

Several studies have confirmed the neuromuscular effects of jaw motor activity on the postural stability of humans, but the mechanisms of functional coupling of the craniomandibular system (CMS) with human posture are not yet fully understood. The purpose of our study was, therefore, to investigate whether submaximum biting affects the kinematics of the ankle, knee, and hip joints and the electromyographic (EMG) activity of the leg muscles during bipedal narrow stance and single-leg stance. Twelve healthy young subjects performed force-controlled biting (FB) and non-biting (NB) during bipedal narrow stance and single-leg stance. To investigate the effects of FB on the angles of the hip, knee, and ankle joints, a 3D motion-capture system (Vicon MX) was used. EMG activity was recorded to enable analysis of the coefficient of variation of the muscle co-contraction ratios (CVR) of six pairs of postural muscles. Between FB and NB, no significant differences were found for the mean values of the angles of the ankle, knee, and hip joints, but the standard deviations were significantly reduced during FB. The values of the ranges of motion and the mean angular velocities for the three joints studied revealed significant reduction during FB also. CVR was also significantly reduced during FB for five of the six muscle pairs studied. Although submaximum biting does not change the basic strategy of posture control, it affects neuromuscular co-contraction patterns, resulting in increased kinematic precision.     

A unified approach for revealing multiple balance recovery strategies

In human balance recovery, different strategies have been proposed with generally overlooked knee motions but extensive focus on the ankle, hip, and step strategies. It is not well understood whether maintaining balance is regulated at the lower “muscular–articular” level of coordinating segment joints or at a higher level of controlling whole body dynamics. Whether balance control is to minimize joint degrees of freedom (DOF) or utilize all the available DOF also remains unclear. This study aimed to use a realistic musculoskeletal human model to identify multiple balance recovery strategies with a single optimization criterion. Movements were driven by neural excitations (which activated muscle force generation) and were assumed to be symmetric. Balance recoveries were simulated with forward-inclined straight body postures as the initial conditions. When the position of the toes was fixed, balance was regained with virtually straight knees and mixed ankle/hip strategies. Under a severely perturbed condition, use of the forward hop strategy after releasing the fixed-toes constraint indicated spontaneous recruitment or suppression of DOF, which mimicked functions of optimally computed CNS commands in humans. The results also indicated that increase/decrease in the number of DOF depends on the imposed perturbation intensity and movement constraints.     

Muscle force compensation among synergistic muscles after fatigue of a single muscle

PurposeThe aim of this study was to examine control strategies among synergistic muscles after fatigue of a single muscle. It was hypothesized that the compensating mechanism is specific for each fatigued muscle.MethodsThe soleus (SOL), gastrocnemius lateralis (GL) and medialis (GM) were fatigued in separate sessions on different days. In each experiment, subjects (n = 11) performed maximal voluntary contractions prior to and after fatiguing a single muscle (SOL, GL or GM) while the voluntary muscle activity and torque were measured. Additionally, the maximal single twitch torque of the plantarflexors and the maximal spinal reflex activity (H-reflex) of the SOL, GL and GM were determined. Fatigue was evoked using neuromuscular stimulation.ResultsFollowing fatigue the single twitch torque decreased by −20.1%, −19.5%, and −23.0% when the SOL, GL, or GM, have been fatigued. The maximal voluntary torque did not decrease in any session but the synergistic voluntary muscle activity increased significantly. Moreover, we found no alterations in spinal reflex activity.ConclusionsIt is concluded that synergistic muscles compensate each other. Furthermore, it seems that self-compensating mechanism of the fatigued muscles occurred additionally. The force compensation does not depend on the function of the fatigued muscle.     

Development of Indirect Measures of Conscientiousness: Combining a Facets Approach and Network Analysis

Because indirect measures of personality self‐concepts such as the Implicit Association Test (IAT) allow tapping into automatic processes, they can offer advantages over self‐report measures. However, prior investigations have led to mixed results regarding the validity of indirect measures of conscientiousness. We suggest that these results might be due to a failure to consider the different facets of conscientiousness. These facets are of crucial importance because they are associated differentially with other psychobiological constructs and they are also characterized by different mechanisms. Therefore, focusing on facets while developing indirect measures of conscientiousness may improve the validity of such measures. In Study 1, we conducted a psycholexical investigation to develop one IAT for each conscientiousness facet. In Study 2, we examined the convergent and discriminant validities of each facet IAT in relation to self‐report measures, peer‐report measures and self‐report behavioural indicators, and we investigated differential associations of the conscientiousness facets with working memory capacity and self‐control. We employed network analysis as a novel approach to elucidate differential relationships involving personality facets. The results corroborated the convergent and discriminant validity of the conscientiousness facet IATs with self‐reports and showed that the conscientiousness facets were differentially associated with working memory capacity and with self‐control. Copyright © 2015 European Association of Personality Psychology     

Reset a task set after five minutes of mindfulness practice

This study aimed to evaluate the impact of a brief mindfulness practice on reducing the carryover effect caused by a previous task set and to determine the mechanism for its effectiveness. Experiment 1 showed that a memorized color interfered with subsequent visual search as a singleton distractor only when color was a defining feature for the search target. In Experiment 2, three interventions (scene-viewing, distraction, and mindfulness practice) were implemented across three groups for five minutes between two blocks; color was relevant to search in the first block and irrelevant in the second. Only the mindfulness group showed a non-significant carryover effect. Experiment 3 demonstrated that the scene-viewing participants continued adopting a suppressive mode of attentional control on a previously distracting color during letter judgment. In contrast, mindfulness practice could reset a task set. Mindfulness practice could enhance concentration in the present moment via reconfiguring the mode of attentional control.     

How to improve the appropriation of space and the morale of residents in nursing homes

This study proposes a simple methodology to improve the quality of life of residents in nursing homes. In the experimental condition, an intervention based on the feeling of control, the technique of touching and “you are free to…” was implemented. Assessment of the residents’ appropriation of their personal space and their morale was made one month later. Data showed a significant improvement in both parameters in the experimental condition, whereas values remained stable in the control group, which did not receive the intervention.