When failure is not an option: a police firearms training concept for improving decision-making in shoot/don't shoot scenarios.

Sometimes, policing requires a quick and correct assessment of potentially hazardous situations. The training of tactical gaze control and visual attention, and its positive impact on efficient shoot/don't shoot decisions in police cadets' use of firearms has recently been demonstrated. On this basis, we designed an individual videobased police firearms training that was grounded on the Four-Component Instructional Design Model (4C/ID). We shifted toward an individual blended learning approach where we applied an intervention training focused on situational awareness, tactical gaze control, and visual attention. In a preregistered lab experiment, N = 45 senior police officers were randomly allocated to the intervention training or an active control training that resembled a traditional police firearms training. Both groups watched a self-produced educational video before proceeding to the practical training in our indoor firing range. In a pre- and post-test, they engaged in realistic shoot/don't shoot video scenarios. Both groups did very well regarding decision-making, the optimal muzzle position, and the tactical conduct to keep both eyes open before shooting. Although both groups performed on a comparable level in the pre-test's shoot scenarios, the intervention group significantly improved their response times and time until the first hit. Overall, we were able to provide an adapted, didactically based police firearms training that supplements current standards. We demonstrated that experts are still susceptible to innovative training concepts and therefore substantiate the recommendation to devote more attention to approaches that emphasize the importance of situational awareness, tactical gaze control, and visual attention in police firearms training.

The concept of "Work-Life-Blending": a systematic review.

Work-Life Blending refers to the permeability and dissolution of boundaries between work and personal life, bringing these domains closer together. However, a comprehensive, holistic definition or conceptualisation of Work-Life-Blending is currently lacking. This research aims to address this gap by conducting a systematic literature review to define and clarify the concept. The primary objective is to identify the key factors and dimensions of Work-Life-Blending by reviewing the current state of research, and by offering a clear and precise conceptual framework to guide further research in developing measurable and concrete concepts. We conducted a systematic review following the PRISMA guidelines to achieve this, drawing on keyword-based searches. We searched for English or German manuscripts in the electronic databases Business Source Premier and PsycARTICLES, using keywords such as "blending," "blurring," "fusion," "Entgrenzung," "Verschmelzung," "Vermischung," "boundary," "border," or "demarcation" in combination with "work" and "life." From 1,400 screened references between 2000 and 2023, we identified 302 eligible articles. After applying exclusion criteria, 51 records were retained. Employing a holistic approach, we developed a coding scheme to analyse the articles focusing on antecedents, processes, and outcomes of Work-Life-Blending. Articles were prioritized based on their impact, relevance, and data content. Our analysis revealed a diverse field, and we adopted Clark's central concepts (2000) to categorize Work-Life Blending into four key areas: Domains, Borders, Individual, and Interindividual. Structural analysis allowed us to gain deeper insights into the multifaceted nature of the research field. Diversification was evident in studies exploring various aspects, such as the combination of dimensions (e.g., organizational and individual factors), correlations between factors (e.g., working conditions), and the introduction of new constructs (e.g., motivational processes). Our research addresses a significant knowledge gap in the field of Work-Life-Blending, making valuable contributions to the existing body of knowledge. By examining key categories and proposing an extended definition, this study provides a robust foundation for further investigations. As a result, we established a classification of the determinants. Given the high degree of diversification, we offer a comprehensive framework for future research, contributing to a deeper understanding of Work-Life Blending.

Financial incentives enhance adaptation to a sensorimotor transformation.

Adaptation to sensorimotor transformations has received much attention in recent years. However, the role of motivation and its relation to the implicit and explicit processes underlying adaptation has been neglected thus far. Here, we examine the influence of extrinsic motivation on adaptation to a visuomotor rotation by way of providing financial incentives for accurate movements. Participants in the experimental group "bonus" received a defined amount of money for high end-point accuracy in a visuomotor rotation task; participants in the control group "no bonus" did not receive a financial incentive. Results showed better overall adaptation to the visuomotor transformation in participants who were extrinsically motivated. However, there was no beneficial effect of financial incentives on the implicit component, as assessed by the after-effects, and on separately assessed explicit knowledge. These findings suggest that the positive influence of financial incentives on adaptation is due to a component which cannot be measured by after-effects or by our test of explicit knowledge. A likely candidate is model-free learning based on reward-prediction errors, which could be enhanced by the financial bonuses.

Using scissors to bisect a line: a perception-action dissociation in complex tool use.

Previous research has shown that unilateral visual neglect is improved when patients are required to actively grasp an object at its center, rather than only pointing to its center. A similar dissociation between pointing and grasping responses has been reported for pseudoneglect, a spatial bias toward the left side of space that is normally exhibited by healthy participants. Among other theories, the two-visual-streams hypothesis has been offered as an explanation for these dissociations. According to this hypothesis, highly practiced actions that are performed under easily available visual input (e.g., grasping an object) are controlled by the dorsal stream and can resist perceptual judgment biases. We investigated whether, in pseudoneglect, dissociations between perceptual judgments and motor-manipulative responses occur when participants have to respond with complex tools that are highly practiced but that have been shown to rely on both ventral- and dorsal-stream processing. In a standard line bisection task, participants had to either mark the center of a line with a pencil or cut the line in two halves using a pair of scissors. The results indicated the typical leftward bias (pseudoneglect) in the pencil task, whereas performance was much more accurate in the scissors task. These results show that actions featuring complex tool use can resist perceptual judgment biases, and the findings are discussed with reference to existing accounts of perception-action dissociations.

Effective part-task training as evidence of distinct adaptive processes with different time scales.

For some types of visuo-motor transformations like large visuo-motor rotations or the complex transformation of a sliding first-order lever, distinct adaptive processes have been hypothesized that produce a rapid, discrete approximation of the transformation and a slow, graded fine tuning, respectively. Here we investigate whether part-task training of only the second of these processes, namely the fine tuning, transfers to the subsequent performance in a condition with the full transformation of the sliding first-order lever. Therefore, we compared performance of three groups with different practice conditions during transfer to the full transformation. While two groups only practiced the fine tuning without the right-left inversion of the lever prior to transfer, a third group practiced the full lever transformation. Our results show a positive, but less than perfect transfer of the isolated practice of the fine tuning on performance with the full transformation. For the fine tuning itself, transfer was not reliably different from being perfect. The observation that the fine tuning can be acquired separately and added to the later adaptation to the left-right inversion of the lever supports the notion that these slow and fast processes progress rather independently. The additional finding that the preceding acquisition of the fine tuning also facilitates the subsequent rapid process could be due to generalized learning-to-learn or to a more precise assignment of movement errors to the process from which they originate.

Movement paths in operating hand-held tools: tests of distal-shift hypotheses.

Extending the body with a tool could imply that characteristics of hand movements become characteristics of the movement of the effective part of the tool. Recent research suggests that such distal shifts are subject to boundary conditions. Here we propose the existence of three constraints: a strategy constraint, a constraint of movement characteristics, and a constraint of mode of control. We investigate their validity for the curvature of transverse movements aimed at a target while using a sliding first-order lever. Participants moved the tip of the effort arm of a real or virtual lever to control a cursor representing movements of the tip of the load arm of the lever on a monitor. With this tool, straight transverse hand movements are associated with concave curvature of the path of the tip of the tool. With terminal visual feedback and when targets were presented for the hand, hand paths were slightly concave in the absence of the dynamic transformation of the tool and slightly convex in its presence. When targets were presented for the tip of the lever, both the concave and convex curvatures of the hand paths became stronger. Finally, with continuous visual feedback of the tip of the lever, curvature of hand paths became convex and concave curvature of the paths of the tip of the lever was reduced. In addition, the effect of the dynamic transformation on curvature was attenuated. These findings support the notion that distal shifts are subject to at least the three proposed constraints.

Towards mastery of complex visuo-motor transformations.

In this paper we review and integrate a set of findings on learning the transformation of a sliding first-order lever, a type of tool with a prominent role in minimal access surgery. Its kinematic transformation is characterized by the so-called fulcrum effect, the inversion of the movement direction of the tip of the lever relative to that of the hand for rotations. A second characteristic is gain anisotropy, which results in curved paths of the tip of the lever for straight paths of the hand and vice versa. An internal model of the kinematic transformation is acquired during practice, the accuracy of which can be assessed in visual open-loop test trials. The accuracy of the acquired internal model is enhanced when visual closed-loop control during practice is impeded, and the accuracy of the internal model is reduced when closed-loop control during practice is facilitated. The internal model consists of a rapidly acquired line-symmetric approximation to the transformation of the sliding lever and a slowly acquired fine tuning. The fine tuning is local, that is, it is specific for the region of the workspace encountered during practice. The internal model is transferred to other regions of the workspace, but not adjusted to the fine tuning appropriate for these regions. Whereas the symmetry approximation is most likely explicit, the fine tuning seems to be represented implicitly. Findings on the straightness of the paths of the tip of the lever and the hand suggest that the internal model of the transformation is confined to initial and final positions of aimed movements, whereas their path is not strictly controlled, but affected by the dynamic transformation of the tool. Only when visual closed-loop control is possible, the path of the effective part of the tool is straightened. These characteristics of the internal model of the sliding first-order lever and its acquisition may be partly specific to sufficiently complex extrinsic transformations that arise from mechanical or electronic extensions of the body.

Generalization of adaptation to a complex visuo-motor transformation across the workspace.

For the efficient use of tools, the visuo-motor transformation relating body movements to movements of the effective part of the tool has to be learned. Here we ask whether adaptation to a complex tool transformation generalizes to new regions of the workspace of the tool. Three groups of participants performed goal-directed movements of a cursor on a computer monitor. The cursor represented the tip of the load arm of a sliding lever, while the hand of the participants moved the tip of the effort arm of the same lever. Each group learned a particular relation between movements of the effort arm and of the load arm as it was associated with a certain region of the workspace. In the transfer test, targets in three different regions of the workspace were presented, only one of them each group had encountered during practice. Adaptation to the visuo-motor transformation turned out to generalize across the workspace of the tool. However, the generalization exhibited different patterns for the three groups which reflected the respective regions of the workspace where the transformation had been learned. We conclude that the acquired internal representation of the visuo-motor transformation is local and does not allow extrapolation to new regions of the workspace. It likely consists of a symmetry approximation, which is valid across the whole workspace of the tool and largely accessible to conscious awareness, and a rather implicit local fine tuning, which is specific to local regions of the workspace.

A progression of approximations to internal models of complex visuo-motor transformations.

Previous research suggests that the acquisition of an internal model of a complex visuo-motor transformation might proceed as a progression of approximations. Here, we test this assumption by comparing performance of three groups of participants during practice and subsequent open-loop tests with three different types of visuo-motor transformation: the kinematic transformation of a sliding first-order lever, a point-symmetric transformation, and a line-symmetric transformation. With the point-symmetric transformation, participants showed the most accurate performance from early practice on and essentially no practice benefit. Movements were not systematically biased toward one of the other transformations. With the line-symmetric transformation, the initially poorer accuracy reached the level of the participants practising the point-symmetric transformation rather rapidly. Early in practice movements according to a point-symmetric transformation were observed. In a similar way the accuracy of participants practising the sliding-lever transformation caught up, but remained worse at the end of practice, nevertheless. With this transformation movements according to a point-symmetric transformation were again observed early in practice, and the movements remained biased toward the line-symmetric transformation. These findings support the notion that the acquisition of an internal model of a complex visuo-motor transformation proceeds in a progression of approximations to the accurate internal representation.

Enhanced mechanical transparency during practice impedes open-loop control of a complex tool.

We investigated the impact of enhanced mechanical transparency during practice on closed-loop performance as well as on the acquisition of an internal representation of the visuo-motor transformation of a lever. Three groups of participants controlled a cursor on a monitor by moving the effort arm of a sliding two-sided lever. The level of mechanical transparency was manipulated by varying the amount of conceptual knowledge about the tool the participants were using as well as by the visualization of the effective part of the tool on the monitor. While for groups cursor- and cursor+ only a cursor representing the tip of the load arm of the lever was visible, group shaft was additionally provided with a representation of the load arm on the monitor. The cursor groups differed in conceptual knowledge about the tool, with only group cursor+ being informed that they were controlling a two-sided lever. Enhanced mechanical transparency, resulting from the visibility of the lever arm, boosted performance in terms of faster and straighter movements when concurrent visual feedback was available, and therefore closed-loop control was possible. In contrast, a detrimental effect of enhanced mechanical transparency during practice on the accuracy of the internal representation of the visuo-motor transformation was observed. When assessing open-loop control in test trials without visual feedback, participants who had previously practiced the tool transformation with the visible lever arm showed larger end point errors than those who had practiced with the cursor only. These findings support the notion that enhanced mechanical transparency of a tool is a type of environmental support which boosts closed-loop performance, but impedes open-loop performance, most likely by serving as a substitute for an internal representation. When practice conditions facilitate closed-loop control, the acquisition of an accurate internal representation of a novel visuo-motor transformation seems to be hampered.

Mind and movement.

Voluntary movements embrace both intentional, conscious and post-intentional, largely automatic processes. Here, we examine these types of processes and the relations between them during preparation and execution of voluntary movements. First, a general overview is given about how intentional and post-intentional components are interleaved to enable successful control of purposeful movements. Second, we briefly describe some post-intentional processes that are triggered by preceding intentions. Third, we discuss findings according to which such post-intentional processes or their results can become accessible to conscious awareness. Under such conditions, automatic and conscious processes can co-occur. We show that intentional interventions into post-intentional processes can be overridden by automatic processes, can interfere with automatic processes and can be independent so that their outcomes add to those of automatic processes.

The death of handwriting: secondary effects of frequent computer use on basic motor skills.

The benefits of modern technologies such as personal computers, in-vehicle navigation systems, and electronic organizers are evident in everyday life. However, only recently has it been proposed that the increasing use of personal computers in producing written texts may significantly contribute to the loss of handwriting skills. Such a fundamental change of human habits is likely to have generalized consequences for other basic fine motor skills as well. In this article, the authors provide evidence that the skill to produce precisely controlled arm-hand movements is related to the usage of computer keyboards in producing written text in everyday life. This result supports the notion that specific cultural skills such as handwriting and typing shape more general perceptual and motor skills. More generally, changing technologies are associated with generalized changes of the profile of basic human skills.

Implicit and explicit adjustments to extrinsic visuo-motor transformations and their age-related changes.

Humans have unique abilities in using tools. The skilled and goal-directed use of a tool implies that processes of motor control can be adjusted to the transformation of the movement of a part of the body into the movement of the effective part of the tool. A common example is the transformation of a hand movement in the motion of a cursor on a computer monitor. In part the adjustments to such transformations are implicit, that is, without conscious awareness of the novel transformation and the appropriate change of one's own movements. However, the adjustments can also be explicit and intentional. We review a series of experiments which show that implicit and explicit adjustments to a novel visuo-motor gain are additive. This finding suggests that the processes which generate different types of adjustment are functionally independent. In a second series of experiments it turned out that at older adult age explicit adjustments to novel visuo-motor transformations are impaired, whereas implicit adjustments remain unaffected across working age.

Type of visual feedback during practice influences the precision of the acquired internal model of a complex visuo-motor transformation.

This study investigated the influence of the type of visual feedback during practice with a complex visuo-motor transformation of a sliding two-sided lever on the acquisition of an internal model of the transformation. Three groups of participants, who practised with different types of visual feedback, were compared with regard to movement accuracy, curvature and movement time. One group had continuous visual feedback during practice and two groups were presented terminal visual feedback, either only the end position of the movement or the end position together with the trajectory of the cursor. Results showed that continuous visual feedback led to more precise movement end positions during practice than terminal visual feedback, but to less precise movements during open-loop tests. This finding indicates that terminal visual feedback supports the development of a precise internal model of a new visuo-motor transformation. However, even terminal feedback of the cursor trajectory during practice did not result in an internal model, which includes appropriate curvatures of hand movements. STATEMENT OF RELEVANCE: This paper presents results on the influence of type of visual feedback on learning the complex motor skill of controlling a sliding lever. These findings contribute to the conceptual basis of optimised training procedures for the acquisition of sensori-motor skills required for the mastery of instruments utilised in minimally invasive surgery.

The trajectory of adaptation to the visuo-motor transformation of virtual and real sliding levers.

We studied adaptation to the visuo-motor transformation of a virtual and a real two-sided sliding lever. In a previous study (Sülzenbrück and Heuer in Exp Brain Res 195:153-165, 2009) we had found essentially no differences. However, adaptation had been restricted to a simplified symmetry approximation of the transformation. In the present study practice conditions were designed to facilitate adaptation (e.g., terminal rather than continuous visual feedback). In visual open-loop tests, differences between the effects of practice with a virtual and a real lever were found for curvature of hand movements, whereas movement end positions were not different. Curved hand movements induced by the use of the real lever persisted in subsequent open-loop tests with the virtual lever. Early in practice end-position errors were strongly biased toward the simplified symmetry approximation, but this bias was reduced later on. Thus, the symmetry approximation is a transient state in the trajectory of adaptation that is reached quickly and from which there is a slow and gradual transition to an accurate internal representation of the visuo-motor transformation of the sliding lever.

Trajectories in operating a handheld tool.

The authors studied the trajectories of the hand and of the tip of a handheld sliding first-order lever in aiming movements. With this kind of tool, straight trajectories of the hand are generally associated with curved trajectories of the tip of the lever and vice versa. Trajectories of the tip of the lever exhibited smaller deviations from straight paths than did trajectories of the hand, even though the cursor, which displayed the position of the tip of the lever on a computer monitor, was invisible during movement execution. These observations suggest that movement of the effective part of the tool is the primary kinematic variable in motor planning and control, even in the absence of continuous visual feedback. The presence of continuous visual feedback did not change the basic pattern of results, except that the remaining deviations from straight paths of the tip of the lever became smaller. These deviations most likely result from an inertial anisotropy of the tool, and they are reduced by visually based online corrections.

Learning the visuomotor transformation of virtual and real sliding levers: simple approximations of complex transformations.

Learning to operate a complex tool such as a sliding lever can be conceived as learning both a kinematic and a dynamic transformation. We investigated whether the presence of the dynamic transformation has an inhibitory or a facilitative effect on learning to control a sliding lever. Furthermore, we examined the characteristics of the internal model of the kinematic transformation of the lever in visual open-loop trials. In the experiment, one group of participants practiced with only the kinematic transformation of the lever (virtual lever), the other group practiced with both the kinematic and the dynamic transformation (physical lever). Visual feedback was continuously present during practice. Results showed only marginal differences between both groups in open-loop tests. This finding is likely to be related to the fact that in both groups a simplified approximation of the kinematic transformation was acquired, in particular a symmetry approximation. With such an approximation the target for the hand movement is derived from the visual target for the tip of the lever as the position which is symmetric around a sagittal axis.

Functional independence of explicit and implicit motor adjustments.

Adaptation to novel visuomotor transformations for example when navigating a cursor on a computer monitor by using a computer mouse, can be explicit or implicit. Explicit adjustments are made when people are informed about the occurrence and the type of a novel visuomotor transformation and intentionally modify their movements. Implicit adjustments, in contrast, are made without reportable knowledge of a novel visuomotor transformation and without a change intention. The relation of implicit adjustments to explicit adjustments needs further clarification. Here we show that these two types of adjustment occur at the same time and remain functionally independent. The size of total adjustment turned out to be the sum of explicit and implicit adjustments measured in isolation, even when both processes produce opposite outcomes. In perspective our results demonstrate that automatic, implicit processes of motor control are not superseded by intentional, explicit ones, but only superposed.

A case of spider phobia in a congenitally blind person.

Vision is the key sensory system in humans, leading to the implicit assumption that the acquisition of spider phobia is predominantly mediated through the visual pathway. We report on a congenitally blind person with spider phobia, showing that the acquisition of spider phobia does not necessarily depend on visual cues.