A perception-action strategy for hummingbirds

Many human and animal tasks are thought to be controlled with the tau informational variable. It is widely accepted that controlling the rate of change of tau (tau) during decelerative tasks, such as when braking or landing, is one common perceptual control strategy. However, many tasks require accelerating before decelerating to a goal, such as reaching. An advancement of tau theory shows how a single action formula may be used to control the full action unit from initiation to peak velocity, and to rest at the goal, with the same perceptual tau information as before and accounting for the same decelerative kinematics as before. Here, we test the theory against data from high-speed video of a hummingbird flying to its flower feeder. We find that the theory accounts for 97% of the variance in the data, and thus supports it.     

The goal of locomotion: Separating the fundamental task from the mechanisms that accomplish it

Human locomotion has been well described but is still not well understood. This is largely true because the observable aspects of locomotion—neuromuscular activity that generates forces and motions—relate to both the task solution and the problem being solved. Identifying the fundamental task achieved in locomotion makes it possible to critically evaluate the motor control strategy used to accomplish the task goal. We contend that the readily observed movements and activities of locomotion should be considered mechanism(s). Our proposal is that the fundamental task of walking and running is analogous to flight, and should be defined in terms of the interaction of the individual’s mass with the medium in which it moves: a low-density fluid for flight, or the supporting substrate for legged locomotion. A rigorous definition of the fundamental task can help identify the constraints and opportunities that influence its solution and guide the selection of appropriate mechanisms to accomplish the task effectively. The results from robotics-based modeling studies have demonstrated how the interaction of the mass and substrate can be optimized, making the goal of movement a defined trajectory of the individual’s mass. We assessed these concepts by evaluating the ground reaction forces generated by an optimization model that satisfies the task but uses none of the mechanisms that are available to the human leg. Then we compared this model to normal human walking. Although it is obvious that the specific task of locomotion changes with a variety of movement challenges, clearly identifying the fundamental task of locomotion puts all other features in an interpretable context.     

Salivary progesterone is associated with reduced coherence of attentional, cognitive, and motivational systems

The present study tested whether the hypothesis that high levels of progesterone (P) have a decoupling effect on the function of the brain hemispheres (Hausmann & Gunturkun, 2000) also extends to attentional functions, referential connections between verbal and nonverbal representations and the degree to which implicit motivational needs match a person's explicit goal commitments. Participants (28 women on oral contraceptives, 14 naturally cycling women, 50 men) completed the Lateralized Attention Network Task (Greene et al., 2008), a measure of the alerting, orienting, and conflict-resolution functions of attention for each hemisphere; a measure of referential competence (i.e., the ability to quickly name nonverbal information); a measure of the implicit motives power, achievement, and affiliation; and a content-matched personal goal inventory. In addition, they provided a saliva sample that was assayed for P and cortisol (C). Higher levels of P were associated with lower interhemispheric correlations for alerting and orienting, but with a higher correlation of conflict-resolution performance. Higher P was also associated with longer interhemispheric transfer time, lower congruence between implicit motives and explicit goal commitments and, after controlling for C, with lower referential competence. These results suggest that (a) P is associated with the degree to which attentional functions are correlated between hemispheres, although in a different direction for more posterior (alerting and orienting: decoupling) than for more anterior functions (conflict resolution: coupling), (b) that high P is associated with other indicators of reduced functional coherence between cognitive systems (longer interhemispheric transfer time, lower referential competence), and (c) that high P is also associated with low coherence between implicit and explicit motivational systems.     

Boundaries for career success? How work–home integration and perceived supervisor expectation affect careers

The necessity to actively manage the work–home boundaries has drastically increased. We postulate that work–home integration may affect individuals' subjective career success via its positive effects on work goal attainment and exhaustion. Furthermore, we study perceived supervisor expectation for employee work–home integration as a boundary condition. Our three-wave online survey with 371 employees showed support for the two hypothesized moderated mediation effects. Work–home integration preference is indirectly related to subjective career success: (1) positively via home-to-work transitions and work goal attainment and (2) negatively via home-to-work transitions and exhaustion. Perceived supervisor expectation constrained work–home integration preference's direct effect on home-to-work transitions and indirect effects on subjective career success. Exploratory analysis revealed that exhaustion negatively affected all career success dimensions, whereas work goal attainment was only related to some. Our results indicate that supervisor expectation can override the effect of employee's work–home integration preference on home-to-work transitions which have a double-edged sword effect on subjective career success. Our study contributes to integrating the careers and work–life interface literature and incorporating contextual factors. Furthermore, with the exploration of differential effects on subjective career success, we advance our understanding of this outcome's nomological network.