Moving and memorizing: motor planning modulates the recency effect in serial and free recall

Impact of lighting environment on human performance and prediction modeling of personal visual comfort in enclosed cabins

Enclosed cabins are of great significance in various fields, including national defense, scientific research, and industrial applications. It is important to clarify the impact of the lighting environment in these cabins on the people operating within them. This study investigated the effects of the lighting environment in enclosed cabins on the physiological, operational, and comfort performance of operators through simulated experiments. In Addition, using the Random Forest Algorithm and ExpandNet technique, we developed a prediction model to evaluate the comfort level of the lighting environment for personnel in enclosed cabins. The results indicated that pupil diameter exhibited the highest sensitivity to ambient light. The appropriate luminance combination of the screen and the ambient scene have a positive effect on human performance. In particular, it was observed that the average cognitive performance and comfort of participants tended to be relatively high in the luminance combinations 13, 14, and 15 at CCT 5500 K. The screen luminance of these combinations are all 284.75 cd/m2. Although no statistically significant relationship was found between the cognitive performance of the participants and their comfort, the comfort of the participants tended to decrease after the cognitive operations was completed. According to the proposed personal comfort prediction model, the visual comfort of different people varies even under the same lighting conditions. This study provides a solid theoretical basis for improving the design of lighting environments in enclosed spaces and contributes to developing a pleasant and productive working environment within limited cabins.

Getting stuck in a rut as an emergent feature of a dynamic decision-making system

Human sensorimotor decision making has a tendency to get 'stuck in a rut', being biased towards selecting a previously implemented action structure (hysteresis). Existing explanations propose this is the consequence of an agent efficiently modifying an existing plan, rather than creating a new plan from scratch. Instead, we propose that hysteresis is an emergent property of a system learning from the consequences of its actions. To examine this, 152 participants moved a cursor to a target on a tablet device while avoiding an obstacle. Hysteresis was observed when the obstacle moved sequentially across the screen between trials, whereby the participant continued moving around the same side of the obstacle despite it now requiring a larger movement than the alternative. Two further experiments (n = 20) showed an attenuation when time and resource constraints were eased. We created a simple computational model capturing probabilistic estimate updating that showed the same patterns of results. This provides, to our knowledge, the first computational demonstration of how sensorimotor decision making can get 'stuck in a rut' through the updating of the probability estimates associated with actions.

State-level working memory and dysregulated eating in children and adolescents: An exploratory ecological momentary assessment study

BACKGROUND

Children with loss of control (LOC) eating and overweight/obesity have relative deficiencies in trait-level working memory (WM), which may limit adaptive responding to intra- and extra-personal cues related to eating. Understanding of how WM performance relates to eating behavior in real-time is currently limited.

METHODS

We studied 32 youth (ages 10-17 years) with LOC eating and overweight/obesity (LOC-OW; n = 9), overweight/obesity only (OW; n = 16), and non-overweight status (NW; n = 7). Youth completed spatial and numerical WM tasks requiring varying degrees of cognitive effort and reported on their eating behavior daily for 14 days via smartphone-based ecological momentary assessment. Linear mixed effects models estimated group-level differences in WM performance, as well as associations between contemporaneously completed measures of WM and dysregulated eating.

RESULTS

LOC-OW were less accurate on numerical WM tasks compared to OW and NW (ps < .01); groups did not differ on spatial task accuracy (p = .41). Adjusting for between-subject effects (reflecting differences between individuals in their mean WM performance and its association with eating behavior), within-subject effects (reflecting variations in moment-to-moment associations) revealed that more accurate responding on the less demanding numerical WM task, compared to one's own average, was associated with greater overeating severity across the full sample (p = .013). There were no associations between WM performance and LOC eating severity (ps > .05).

CONCLUSIONS

Youth with LOC eating and overweight/obesity demonstrated difficulties mentally retaining and manipulating numerical information in daily life, replicating prior laboratory-based research. Overeating may be related to improved WM, regardless of LOC status, but temporality and causality should be further explored.

PUBLIC SIGNIFICANCE STATEMENT

Our findings suggest that youth with loss of control eating and overweight/obesity may experience difficulties mentally retaining and manipulating numerical information in daily life relative to their peers with overweight/obesity and normal-weight status, which may contribute to the maintenance of dysregulated eating and/or elevated body weight. However, it is unclear whether these individual differences are related to eating behavior on a moment-to-moment basis.

Associations between Executive Functions and Sensorimotor Performance in Children at Risk for Learning Disabilities

Executive functions (EF) and sensorimotor skills play a critical role in children's goal-directed behavior and school readiness. The aim of the current study is to provide new insights into the relationship between executive functions and sensorimotor development by considering the risks associated with learning difficulties. Therefore, we investigate the predictive role of EF and sensorimotor skills in the development of learning difficulties during preschool years. Ninety-five preschool children (5-7 years old) were tested, comparing the performance of children that are at risk of learning difficulties (n = 55) to the performance of typically developing children (n = 40). Participants completed a battery for the assessment of sensorimotor skills (i.e., Southern California Sensory Integration Test: postural imitation, body midline crossing, bilateral motor coordination, and standing balance with eyes open) and executive functions (i.e., inhibition, cognitive flexibility, and verbal working memory). Our results show that children at risk for learning difficulties exhibited more impairments on sensorimotor and EF measures (inhibition and verbal working memory) when compared with TD children. We ran three separate binary logistic regression analyses to assess the relative influence of EF and sensorimotor functions on predicting risk for learning difficulties. Our findings demonstrated that verbal working memory as EF function (odd ratio (OR) = 0.91, 95% CI 0.78-0.91, P = 0.05) and standing balance skills as a sensorimotor skill (odd ratio (OR) = 0.86, 95% CI 0.81-0.98, P = 0.01) were the strongest predictors of risk for learning difficulties. The findings point to the importance of supporting children's executive function development and promoting sensorimotor development, as both fundamentally influence school readiness.

Choice of end-state comfort is dependent upon the time spent at the beginning-state and the precision requirement of the end-state

Choice of posture while grasping an object typically depends upon several factors including the time spent in that posture, what postures were held prior to choosing that posture, and the precision required by the posture. The purpose of this study was to test choice of end-state thumb-up posture based on time spent at the beginning-state and the precision requirement of the end-state. To determine choice of thumb-up based on time or precision, we varied how long a subject had to hold the beginning state before moving an object to an end location. We made end-state precision either small or large and eliminated the precision needed to stand the object up at the end of the movement. A choice between "comfort" at the beginning or precision at the end-state would be demanded by the conditions with long beginning-state hold times and high precision demands. We aimed to determine which aspect of movement was of greater importance to individuals, overall "comfort" or precision. When the requirement was to hold the initial grasp longer, and the end-target was large, we predicted that we would see more thumb-up postures adopted at the beginning state. When the final placement was small and the initial posture was not constrained, we predicted we would see thumb-up postures adopted at the end state. On average, we found that, as beginning-state grasp time increased, more individuals chose beginning-state thumb-up postures. Perhaps, not surprisingly, we found distinct individual differences within our sample. Some individuals seemed to choose beginning-state thumb-up postures nearly 100% of the time, while other individuals chose end-state thumb-up postures nearly 100% of the time. Both the time spent in a posture and its precision requirements influenced planning, but not necessarily in a systematic way.

Age-related differences in upper limb motor performance and intrinsic motivation during a virtual reality task

BACKGROUND

In recent years, virtual reality (VR) has evolved from an alternative to a necessity in older adults for health, medical care, and social interaction. Upper limb (UL) motor skill, is an important ability in manipulating VR systems and represents the brain's regulation of movements using the UL muscles. In this study, we used a haptic-feedback Virtual Box and Block Test (VBBT) system and an Intrinsic Motivation Inventory (IMI) to examine age-related differences in UL motor performance and intrinsic motivation in VR use. The findings will be helpful for the development of VR applications for older adults.

METHODS

In total, 48 young and 47 older volunteers participated in our study. The parameters including VBBT score, number of velocity peaks, velocity, grasping force and trajectory length were calculated to represent the task performance, manual dexterity, coordination, perceptive ability and cognitive ability in this study.

RESULTS

Age-related differences could be found in all the parameters (all p <  0.05) in VR use. Regression analysis revealed that the task performance of young adults was predicted by the velocity and trajectory length (R² = 64.0%), while that of older adults was predicted by the number of velocity peaks (R² = 65.6%). Additionally, the scores of understandability, relaxation and tiredness were significantly different between the two groups (all p <  0.05). In older adults, the understandability score showed large correlation with the IMI score (|r| = 0.576, p <  0.001). In young adults, the correlation was medium (|r| = 0.342, p = 0.017). No significant correlation was found between the IMI score and VBBT score (|r| = 0.142, p = 0.342) in older adults, while a medium correlation (|r| = 0.342, p = 0.017) was found in young adults.

CONCLUSIONS

The findings demonstrated that decreased smoothness in motor skills dominated the poor VR manipulation in older adults. The experience of understandability is important for older adults' intrinsic motivation in VR use.

Hysteresis in motor and language production

Hysteresis in motor planning and syntactic priming in language planning refer to the influence of prior production history on current production behaviour. Computational efficiency accounts of action hysteresis and theoretical accounts of syntactic priming both argue that reusing an existing plan is less costly than generating a novel plan. Despite these similarities across motor and language frameworks, research on planning in these domains has largely been conducted independently. The current study adapted an existing language paradigm to mirror the incremental nature of a manual motor task to investigate the presence of parallel hysteresis effects across domains. We observed asymmetries in production choice for both the motor and language tasks that resulted from the influence of prior history. Furthermore, these hysteresis effects were more exaggerated for subordinate production forms implicating an inverse preference effect that spanned domain. Consistent with computational efficiency accounts, across both task participants exhibited reaction time savings on trials in which they reused a recent production choice. Together, these findings lend support to the broader notion that there are common production biases that span both motor and language domains.

Manual action re-planning interferes with the maintenance process of working memory: an ERP investigation

The current study investigated the re-planning of the grasping movements, its functional interactions with working memory (WM), and underlying neurophysiological activity. Mainly, the current study investigated the movement re-planning interference with WM domains (verbal, visuospatial) and processes (maintenance, retrieval). We combined a cognitive-motor dual-task paradigm with an EEG setting. Thirty-six participants completed the verbal and visuospatial versions of a WM task concurrently with a manual task which required performing a grasp-and-place movement by keeping the initial movement plan (prepared movement condition) or changing it for reversing the movement direction (re-planned movement condition). ERPs were extracted for the prepared and re-planned conditions in the verbal and visuospatial tasks separately during the maintenance and retrieval processes. ERP analyses showed that during the maintenance process of both the verbal and visuospatial tasks, the re-planned movements compared to the prepared movements generated a larger positive slow wave with a centroparietal maximum between 200 and 700. We interpreted this ERP effect as a P300 component for the re-planned movements. There was no ERP difference between the planned and re-planned movements during the retrieval process. Accordingly, we suggest that re-planning the grasp-and-place movement interfered at least with the maintenance of the verbal and visuospatial domains, resulting in the re-planning costs. More generally, the current study provides the initial neurophysiological investigations of the movement re-planning–WM interactions during grasping movements, and contributes to a better understanding of the neurocognitive mechanisms underlying manual action flexibility.

Simulated practice effects on the transfer and retention of gait sequences from the upper to the lower extremity

This study investigated transfer of training from upper extremity limbs (the index fingers) to the lower extremity limbs (the legs) for performance of three gait sequences of different difficulty. Fifteen subjects participated in the study. Subjects in an iPad training group practiced by sequentially moving their left-and right-hand index fingers across tiles to each of three targets displayed on an iPad for 20 trials. Subjects in a gait training group practiced by sequentially walking across tiles to each of the 3 targets displayed on a screen for 20 trials. A no practice group did not receive practice trials. Immediately following practice of each level of difficulty, a transfer test (20 trials) was given for which subjects walked to the target just practiced. A retention test of 36 trials (12 trials at each difficulty level) was administered 20 min following performance of the last transfer test trial. The retention test showed that reaction times were shorter for the iPad training than gait training and no training groups; anticipatory postural adjustment times were equivalent for the iPad and gait training groups, but shorter than for the no training group; and movement times were shorter for the iPad training group than for the gait training and no training groups. These results suggest that iPad training (upper extremity) followed by performance of gait training (lower extremity) had greater benefits for learning (as measured by the delayed retention test) the gait sequences than practicing the actual gait sequences themselves.

Do People Work Hard to Maintain Social Distance?

How far away from each other people sit or stand reveals much about their social proximity, but merely sitting or standing may not test the limits of social boundaries as much as collaborating on tasks requiring physical coordination. In this study, we asked university students to walk two abreast while carrying a long pipe from one end of a workspace to another. Hurdles in the workspace forced the dyads to decide whether to walk close together without stepping over the hurdles or walk farther apart, stepping over the hurdles. The subjects often chose the latter option, stepping over 18-inch high hurdles rather than walking on level ground.

Dual-task interference in action programming and action planning - Evidence from the end-state comfort effect

In the present study, we examined the extent of interference between a cognitive task (auditory n-back task) and different aspects of motor performance. Specifically, we wanted to find out whether such interference is more pronounced for aspects of planning as compared to programming. Here, motor planning is represented by a phenomenon called the "end-state comfort effect", the fact that we tolerate uncomfortable initial postures in favour of a more comfortable final posture. We asked participants to grasp differently sized cylindrical objects and to place them on target platforms of varying height (grasp-and-place task), So, participants were required to (1) adjust their hand opening to the object width (action programming) and (2) to plan whether to grasp the object higher or lower in order to be able to place it comfortably onto the low or high target platform. We found that participants demonstrated the end-state comfort effect by anticipating the final posture und planning the movement accordingly with a higher object-grasp for low end-target position and lower object-grasp height for high end-target position, respectively. The auditory task was negatively affected by having to perform a visuomotor task in parallel, suggesting that the two tasks share cognitive and attentional resources. No significant impact from the auditory task on the motor tasks was found. Accordingly, it was not possible to determine which of the two motor aspects (programming or planning) contributed more towards the interference observed in the auditory task. To address this question, we carried out a second experiment. For this second experiment we focussed on the interference effects found in the auditory task and contrasted two versions of the grasp-and-place task. In the first version of the task, the height of the target-shelf varied from trial-to-trial but the width of the target object remained the same. We assumed that this version had high planning demands and low programming demands. In the second version the width of the target object varied and the target-shelf height remained constant. Presumably this increased programming demands but reduced planning demands. Significant interference with the auditory task was only found for the first version, supporting the hypothesis that motor planning requires more cognitive resources and thus creates higher multitasking costs.

Repetition effects in action planning reflect effector- but not hemisphere-specific coding

Action choices are influenced by future and recent past action states. For example, when performing two actions in succession, response times (RTs) to initiate the second action are reduced when the same hand is used. These findings suggest the existence of effector-specific processing for action planning. However, given that each hand is primarily controlled by the contralateral hemisphere, the RT benefit might actually reflect effector-independent, hemisphere-specific rather than effector-specific repetition effects. Here, participants performed two consecutive movements, each with a hand or a foot, in one of two directions. Direction was specified in an egocentric reference frame (inward, outward) or in an allocentric reference frame (left, right). Successive actions were initiated faster when the same limb (e.g., left hand-left hand), but not the other limb of the same body side (e.g., left foot-left hand), executed the second action. The same-limb advantage was evident even when the two movements involved different directions, whether specified egocentrically or allocentrically. Corroborating evidence from computational modeling lends support to the claim that repetition effects in action planning reflect persistent changes in baseline activity within neural populations that encode effector-specific action plans.

NEW & NOTEWORTHY Repeated hand use facilitates the initiation of successive actions (repetition effect). This finding has been interpreted as evidence for effector-specific action plans. However, given that each hand is primarily controlled by the contralateral hemisphere, any differences might reflect effector-independent, hemisphere-specific rather than effector-specific processing. We dissociated these alternatives by asking participants to perform successive actions with hands and feet and provide novel evidence that repetition effects in limb use truly reflect effector-specific coding.

What matters in making demand-based decisions: Time alone or difficulty too?

Which task is easier, doing arithmetic problems of specified form for some specified duration, or carrying a bucket of specified weight over some specified distance? If it is possible to choose between the “more cognitive” task and the “more physical” task, how are the difficulty levels of the tasks compared? We conducted two experiments in which participants chose the easier of two tasks, one that involved solving addition or multiplication problems (Experiment 1) or addition problems with different numbers of addends (Experiment 2) for varying amounts of time (in both experiments), and one that involved carrying a bucket of different weights over a fixed distance (in both experiments). We found that the probability of choosing to do the bucket task was higher when the bucket was empty than when it was weighted, and increased when the cognitive task was harder and its duration grew. We could account for the choice probabilities by mapping the independent variables onto one abstract variable, Φ. The functional identity of Φ remains to be determined. It could be interpreted as an inferred effort variable, subjective duration, or an abstract, amodal common code for difficulty.

Developmental Differences in the Relationships Between Sensorimotor and Executive Functions

Background

There is evidence that sensorimotor and executive functions are inherently intertwined, but that the relationship between these functions differ depending on an individual’s stage in development (e.g., childhood, adolescence, adulthood).

Objective

In this study, sensorimotor and executive function performance was examined in a group of children (n = 40; 8–12 years), adolescents (n = 39; 13–17 years), and young adults (n = 83; 18–24 years) to investigate maturation of these functions, and how the relationships between these functions differ between groups.

Results

Adults and adolescents outperformed children on all sensorimotor and executive functions. Adults and adolescents exhibited similar levels of executive functioning, but adults outperformed adolescents on two sensorimotor functioning measures (eye-hand coordination spatial precision and proprioceptive variability). Regression analysis demonstrated that executive functions contribute to children’s sensorimotor performance, but do not contribute to adolescent’s sensorimotor performance.

Conclusion

These findings highlight the key role that developmental stage plays in the relationship between sensorimotor and executive functions. Specifically, executive functions appear to contribute to more successful sensorimotor function performance in childhood, but not during adolescence. It is likely that sensorimotor functions begin to develop independently from executive functions during adolescence, and therefore do not contribute to successful sensorimotor performance. The change in the relationship between sensorimotor and executive functions is important to take into consideration when developing sensorimotor and executive function interventions.

A wearable ring-shaped inertial system to identify action planning impairments during reach-to-grasp sequences: a pilot study

Background

The progressive ageing of the population is leading to an increasing number of people affected by cognitive decline, including disorders in executive functions (EFs), such as action planning. Current procedures to evaluate cognitive decline are based on neuropsychological tests, but novel methods and approaches start to be investigated. Reach-to-grasp (RG) protocols have shown that intentions can influence the EFs of action planning. In this work, we proposed a novel ring-shaped wearable inertial device, SensRing, to measure kinematic parameters during RG and after-grasp (AG) tasks with different end-goals. The aim is to evaluate whether SensRing can characterize the motor performances of people affected by Mild Neurocognitive Disorder (MND) with impairment in EFs.

Methods

Eight Individuals with dysexecutive MND, named d-MND, were compared to ten older healthy subjects (HC). They were asked to reach and grasp a can with three different intentions: to drink (DRINK), to place it on a target (PLACE), or to pass it to a partner (PASS). Twenty-one kinematic parameters were extracted from SensRing inertial data.

Results

Seven parameters resulted able to differentiate between HC and d-MND in the RG phase, and 8 features resulted significant in the AG phase. d-MND, indeed, had longer reaction times (in RG PLACE), slower peak velocities (in RG PLACE and PASS, in AG DRINK and PLACE), longer deceleration phases (in all RG and AG DRINK), and higher variability (in RG PLACE, in AG DRINK and PASS). Furthermore, d-MND showed no significant differences among conditions, suggesting that impairments in EFs influence their capabilities in modulating the action planning based on the end-goal.

Conclusions

Based on this explorative study, the system might have the potential for objectifying the clinical assessment of people affected by d-MND by administering an easy motor test. Although these preliminary results have to be investigated in-depth in a larger sample, the portability, wearability, accuracy, and ease-of use of the system make the SensRing potentially appliable for remote applications at home, including analysis of protocols for neuromotor rehabilitation in patients affected by MND.

The Ultimate Tool: The Body, Planning of Physical Actions, and the Role of Mental Imagery in Choosing Motor Acts

The ultimate tool, it could be said, is the brain and body. Therefore, a way to understand tool use is to study the brain's control of the body. A more manageable aim is to use the tools of cognitive science to explore the planning of physical actions. Here, I focus on two kinds of physical acts which directly or indirectly involve tool use: producing finger-press sequences, and walking and reaching for objects. The main question is how people make choices between finger-press sequences, and how people make choices between walk-and-reach sequences. Are the choices made with reference to motor imagery, in which case the longer the sequences are the longer it takes to choose between them, or are shortcuts taken which rely on distinctive features of the alternatives? The reviewed experiments favor the latter alternative. The general view of action planning emerging from this work is one in which action features are highlighted and held in memory, not just to choose between potential actions but also to control the unfolding of long actions over time. Speculations are offered about tool use.

Working memory load does not affect sequential motor planning

Movement planning disrupts the recall performance in a short term memory task, indicating that both processes share common working memory (WM) resources. In the current study, we tested whether this interference was bidirectional. To this end, we combined an easy or a difficult memory task (depleting different amounts of WM resources) with a sequential motor task (opening a column of drawers). The size of the hysteresis effect in the sequential motor task was measured as a proxy for the fraction of motor plan reuse. The different WM loads created by the memory task had no effect on the fractions of motor plan reuse and motor (re-)planning, which supports the idea that motor planning has priority access to WM. A recency effect (better recall of late items) was absent in a verbal memory task but present in a spatial one. Recency is commonly attributed to the episodic buffer, a non-domain-specific storage of the central executive. The domain-specific interference of the motor task with recency indicates that the second assumption needs to be reevaluated.

Is Language Production Planning Emergent From Action Planning? A Preliminary Investigation

The nature of syntactic planning for language production may reflect language-specific processes, but an alternative is that syntactic planning is an example of more domain-general action planning processes. If so, language and non-linguistic action planning should have identifiable commonalities, consistent with an underlying shared system. Action and language research have had little contact, however, and such comparisons are therefore lacking. Here, we address this gap by taking advantage of a striking similarity between two phenomena in language and action production. One is known as syntactic priming-the tendency to re-use a recently produced sentence structure-and the second is hysteresis-the tendency to re-use a previously executed abstract action plan, such as a limb movement. We examined syntactic priming/hysteresis in parallel language and action tasks intermixed in a single experimental session. Our goals were to establish the feasibility of investigating language and action planning within the same participants and to inform debates on the language-specific vs. domain-general nature of planning systems. In both action and language tasks, target trials afforded two alternative orders of subcomponents in the participant's response: in the language task, a picture could be described with two different word orders, and in the action task, locations on a touch screen could be touched in two different orders. Prime trials preceding the target trial promoted one of two plans in the respective domain. Manipulations yielded higher rates of primed behavior in both tasks. In an exploratory cross-domain analysis, there was some evidence for stronger priming effects in some combinations of action and language priming conditions than others. These results establish a method for investigating the degree to which language planning is part of a domain-general action planning system.

The influence of time constraints on posture choices during an end-state comfort task

People adopt comfortable postures for the end states of motor actions (end-state comfort; Rosenbaum & Jorgensen, 1992). The choice to end comfortably often elicits adoption of uncomfortable beginning states, demonstrating that a sequence of movement is planned in advance of movement onset. Many factors influence the choice of comfortable end-state postures including the greater precision and speed afforded by postures at joint angle mid-ranges (Short & Cauraugh, 1999). To date, there has been little evaluation of the hypothesis that postures are chosen based on minimizing the time spent in uncomfortable postures. The aim of this experiment was to examine how the relative time required to hold beginning and end-state postures influenced the choice of posture. Participants moved a two-toned wooden dowel from one location to another with the requirement to grasp the object and place a specified color down. Participants completed four conditions where no postures were held, only one posture was held, or both postures were held. We predicted more thumb-up postures for positions held longer regardless of whether these postures were at the end or beginning state. Results verified that the constraint of holding the initial posture led to decreased end-state comfort supporting the hypothesis that estimation of time spent in postures is an important constraint in planning. We also note marked individual differences in posture choices, particularly when the object was moved to the left.

Shifts of the point-of-change can be attributed to a lower mechanical cost of motor execution

In a previous study on hand selection in a sequential reaching task, the authors showed a shift of the point-of-change (POC) to the left of the midline. This implies that participants conducted a number of contralateral reaches with their dominant, right hand. Contralateral movements have longer planning and execution times and a lower precision. In the current study, we asked whether lower mechanical costs of motor execution or lower cognitive costs of motor planning compensated for these disadvantages. Theories on hemispheric differences postulate lower mechanical costs in the dominant hemisphere and lower cognitive costs in the left hemisphere (independent of handedness). In right-handed participants, both factors act agonistically to reduce the total cost of right-handed reaches. To distinguish between the cost factors, we had left- and right-hand-dominant participants execute a sequential, unimanual reaching task. Results showed a left-shift of the POC in the right-handed and a right-shift in the left-handed group. Both shifts were similar in magnitude. These findings indicate that only the mechanical cost of motor execution compensates for the disadvantages of the contralateral reaches, while the cognitive cost of motor planning is irrelevant for the POC shift.

Dual-task performance of speech and motor skill: verb generation facilitates grasping behaviour

Pronouncing nouns or verbs while grasping distinctly alters movement. Changes in hand speed and final position occur according to the meaning of the words spoken. These results are typically found when executing a single movement paired with a single word. For example, pronouncing the word 'fast' increased the speed of the hand when reaching to grasp. Our objective was to compare how verb and noun fluency tasks interact with grasping behaviour in a grasp-to-construct task. Because previous imaging research shows that verb and noun production activates distinct neural areas, we reasoned that grasping outcomes would differ according to the category of word produced by participants. Specifically, we hypothesized that verb pronunciation would distinctly affect grasping behaviour compared to producing nouns. We recruited 38 young adults who performed a grasp-to-construct task and two different verbal fluency tasks. Participants completed each task (grasp, verb fluency, and noun fluency) separately as control conditions, and the grasping and each speaking task simultaneously for dual-task conditions. We found that during the dual-task condition, when generating nouns and grasping, participants made significantly more grasping errors (inaccurate grasps) compared to the control and verb dual-task conditions. Moreover, our results revealed a relationship between the number of verbs generated and grasping performance. Participants who generated more verbs were faster and more accurate during the motor component of the dual-task condition. This relationship was not observed when nouns were produced, indicating a unique relationship between verb production and functional grasping. The result is a facilitation effect, diminishing the negative outcome on motor control associated with increased cognitive load (as observed during noun pronunciation).

Hemispheric lateralization does not affect the cognitive and mechanical cost of a sequential motor task

In sequential, repetitive tasks, we often partially reuse former motor plans. This causes a persistence of an earlier adopted posture (termed motor hysteresis). The cost-optimization hypothesis states that a partial reuse reduces the cognitive cost of a movement, while the persistence in a former posture increases its mechanical cost. An optimal fraction of reuse, which depends on the relative cognitive and mechanical cost, minimizes the total movement cost. Several studies postulate differences in mechanical or cognitive cost as a result of hemispheric lateralization. In the current study, we asked whether these differences would result in different fractions of motor plan reuse. To this end, left- and right-handed dominant participants executed a sequential motor task (opening a column of drawers) with their dominant and non-dominant hand. The size of the motor hysteresis effect was measured as a proxy for the fraction of plan reuse. Participants used similar postures and exhibited a similar hysteresis effect, irrespective of hand and handedness. This finding indicates that either the cognitive and mechanical costs of a motor task are unaffected by hemispheric differences or that their effect on motor planning is negligible.

Now and then: Hand choice is influenced by recent action history

Action choices are influenced by recent past and predicted future action states. Here, we demonstrate that recent hand-choice history affects both current hand choices and response times to initiate actions. Participants reach to contact visible targets using one hand. Hand choice is biased in favour of which hand was used recently, in particular, when the biomechanical costs of responding with either hand are similar, and repeated choices lead to reduced response times. These effects are also found to positively correlate. Participants who show strong effects of recent history on hand choice also tend to show strong effects of recent history on response times. The data are consistent with a computational efficiency interpretation whereby repeated action choices confer computational gains in the efficiency of underpinning processes. We discuss our results within the framework of this model, and with respect to balancing predicted gains and losses, and speculate about the possible underlying mechanisms in neural terms.

Task order choices in cognitive and perceptual-motor tasks: The cognitive-load-reduction (CLEAR) hypothesis

A core question in the study of the dynamics of cognition is how tasks are ordered. Given two tasks, neither of which is prerequisite for the other and neither of which brings a clearly greater reward, which task will be done first? Few studies have addressed this question, though recent work has suggested one possible answer, which we here call the cognitive-load-reduction (CLEAR) hypothesis. According to the CLEAR hypothesis, there is a strong drive to reduce cognitive load (to "clear one's mind"). Given two tasks, one of which is more cognitively demanding than the other, the more cognitively demanding task will tend to be done first. We tested this prediction using a novel method inviting participants to freely choose when to perform each of c = 5, 10, or 15 items per category in item-generation tasks relative to b = 10 box-moving tasks. The box-moving tasks were cognitively undemanding relative to the item generation tasks, whose cognitive difficulty presumably grew with c. A full half of our n = 122 participants chose to complete all of the c tasks before performing any of the b tasks, and most other participants chose to complete a majority of the c tasks before any of the b tasks. This result is consistent with the CLEAR hypothesis. Speed on the box-moving task decreased the later the category-generation task was completed, supporting another CLEAR prediction. The general method used here provides direction for future work on task order choices in cognitive and perceptual-motor tasks.

A Simple Model to Estimate the Percentage of Motor Plan Reuse From Hysteresis Effect Size

In sequential tasks, a partial reuse of former motor plans results in a persistence in the former posture (termed hysteresis). The cost-optimization hypothesis states that the percentage of reuse depends on the relative cognitive and mechanical cost of each movement. These costs should be constant across all drawers, yet previous studies found a larger hysteresis effect at the central drawers and declining effects toward the periphery. In the current study, we show that a simple mathematical model that assumes a sigmoid optimal grasp angle function and a fixed percentage of motor plan reuse explains the posture variance in a randomized and an ordered sequential drawer opening task. This finding indicates that (1) the optimal pro/supination angle is a sigmoid function of drawer height, (2) the percentage of motor plan reuse is constant across drawers, and (3) a constant percentage of reuse results in a larger hysteresis effect at the central drawers. Based on the model, the percentage of motor plan reuse in future studies can be estimated from the size of the motor hysteresis effect.

The time for action is at hand

The science of mental life and behavior has paid scant attention to the means by which mental life is translated into physical behavior. Why this is so was the topic of a 2005 American Psychologist article whose main title was "The Cinderella of Psychology." In the present article, we briefly review some of the reasons why motor control was relegated to the sidelines of psychology. Then we point to work showing that experimental psychologists have much to contribute to research on action generation. We focus on studies showing that actions are generated in a way that, at least by default, minimize changes between successive actions. The method is computationally as well as physically economical but also requires consideration of costs, including costs of different kinds. How such costs are compared is discussed in the next section. The final section offers comments about the future of psychologically focused action research. Two additional themes of the review concern methods for studying action generation. First, much can be learned through naturalistic observation. Second, subsequent experiments, designed to check naturalistic observations, can use very simple equipment and procedures. This can make the study of action generation easy to pursue in the psychology laboratory.

Task-specific and variability-driven activation of cognitive control processes during motor performance

It has long been postulated that cognitive and motor functions are functionally intertwined. While the idea received convincing support from neuroimaging studies providing evidence that motor and cognitive processes draw on common neural mechanisms and resources, findings from behavioral studies are rather inconsistent. The purpose of the present study was to identify and verify key factors that act on the link between cognitive and motor functions. Specifically we investigated whether it is possible to predict motor skills from cognitive functions. While our results support the idea that motor and cognitive functions are functionally intertwined and different motor skills entail distinct cognitive functions, our data also strongly suggest that the impact of cognitive control processes on motor skill proficiency depends on performance variability, i.e. on how challenging a motor task is. Based on these findings, we presume that motor skills activate specific cognitive control processes on two levels: basic processes that are solely related to the type of the motor task, and variability-driven processes that come into play when performance variability is high. For practitioners, these findings call for specific and challenging motor training interventions to directly tap into the to-be-improved cognitive skills and to involve a maximum of cognitive processes.

Age-Related Decline in Anticipatory Motor Planning and Its Relation to Cognitive and Motor Skill Proficiency

Anticipatory motor planning abilities mature as children grow older, develop throughout childhood and are likely to be stable till the late sixties. In the seventh decade of life, motor planning performance dramatically declines, with anticipatory motor planning abilities falling to levels of those exhibited by children. At present, the processes enabling successful anticipatory motor planning in general, as do the cognitive processes mediating these age-related changes, remain elusive. Thus, the aim of the present study was (a) to identify cognitive and motor functions that are most affected by normal aging and (b) to elucidate key (cognitive and motor) factors that are critical for successful motor planning performance in young (n = 40, mean age = 23.1 ± 2.6 years) and older adults (n = 37, mean age = 73.5 ± 7.1 years). Results indicate that normal aging is associated with a marked decline in all aspects of cognitive and motor functioning tested. However, age-related declines were more apparent for fine motor dexterity, processing speed and cognitive flexibility. Furthermore, up to 64% of the variance in motor planning performance across age groups could be explained by the cognitive functions processing speed, response planning and cognitive flexibility. It can be postulated that anticipatory motor planning abilities are strongly influenced by cognitive control processes, which seem to be key mechanisms to compensate for age-related decline. These findings support the general therapeutic and preventive value of cognitive-motor training programs to reduce adverse effects associated with high age.

Movement Interferes with Visuospatial Working Memory during the Encoding: An ERP Study

The present study focuses on the functional interactions of cognition and manual action control. Particularly, we investigated the neurophysiological correlates of the dual-task costs of a manual-motor task (requiring grasping an object, holding it, and subsequently placing it on a target) for working memory (WM) domains (verbal and visuospatial) and processes (encoding and retrieval). Thirty participants were tested in a cognitive-motor dual-task paradigm, in which a single block (a verbal or visuospatial WM task) was compared with a dual block (concurrent performance of a WM task and a motor task). Event-related potentials (ERPs) were analyzed separately for the encoding and retrieval processes of verbal and visuospatial WM domains both in single and dual blocks. The behavioral analyses show that the motor task interfered with WM and decreased the memory performance. The performance decrease was larger for the visuospatial task compared with the verbal task, i.e., domain-specific memory costs were obtained. The ERP analyses show the domain-specific interference also at the neurophysiological level, which is further process-specific to encoding. That is, comparing the patterns of WM-related ERPs in the single block and dual block, we showed that visuospatial ERPs changed only for the encoding process when a motor task was performed at the same time. Generally, the present study provides evidence for domain- and process-specific interactions of a prepared manual-motor movement with WM (visuospatial domain during the encoding process). This study, therefore, provides an initial neurophysiological characterization of functional interactions of WM and manual actions in a cognitive-motor dual-task setting, and contributes to a better understanding of the neuro-cognitive mechanisms of motor action control.

Inverting the planning gradient: adjustment of grasps to late segments of multi-step object manipulations

When someone grasps an object, the grasp depends on the intended object manipulation and usually facilitates it. If several object manipulation steps are planned, the first step has been reported to primarily determine the grasp selection. We address whether the grasp can be aligned to the second step, if the second step's requirements exceed those of the first step. Participants grasped and rotated a dial first by a small extent and then by various extents in the opposite direction, without releasing the dial. On average, when the requirements of the first and the second step were similar, participants mostly aligned the grasp to the first step. When the requirements of the second step were considerably higher, participants aligned the grasp to the second step, even though the first step still had a considerable impact. Participants employed two different strategies. One subgroup initially aligned the grasp to the first step and then ceased adjusting the grasp to either step. Another group also initially aligned the grasp to the first step and then switched to aligning it primarily to the second step. The data suggest that participants are more likely to switch to the latter strategy when they experienced more awkward arm postures. In summary, grasp selections for multi-step object manipulations can be aligned to the second object manipulation step, if the requirements of this step clearly exceed those of the first step and if participants have some experience with the task.

Action Priority: Early Neurophysiological Interaction of Conceptual and Motor Representations

Handling our everyday life, we often react manually to verbal requests or instruction, but the functional interrelations of motor control and language are not fully understood yet, especially their neurophysiological basis. Here, we investigated whether specific motor representations for grip types interact neurophysiologically with conceptual information, that is, when reading nouns. Participants performed lexical decisions and, for words, executed a grasp-and-lift task on objects of different sizes involving precision or power grips while the electroencephalogram was recorded. Nouns could denote objects that require either a precision or a power grip and could, thus, be (in)congruent with the performed grasp. In a control block, participants pointed at the objects instead of grasping them. The main result revealed an event-related potential (ERP) interaction of grip type and conceptual information which was not present for pointing. Incongruent compared to congruent conditions elicited an increased positivity (100–200 ms after noun onset). Grip type effects were obtained in response-locked analyses of the grasping ERPs (100–300 ms at left anterior electrodes). These findings attest that grip type and conceptual information are functionally related when planning a grasping action but such an interaction could not be detected for pointing. Generally, the results suggest that control of behaviour can be modulated by task demands; conceptual noun information (i.e., associated action knowledge) may gain processing priority if the task requires a complex motor response.

Motor hysteresis in a sequential grasping and pointing task is absent in task-critical joints

In a prior study (Schütz et al. in Exp Brain Res 2016. doi: 10.1007/s00221-016-4608-6 ), we demonstrated that the cognitive cost of motor planning did not differ in a vertical pointing and grasping task. It was unclear whether the similar cost implied that both tasks required the same number of independent degrees of freedom (IDOFs) or that the number of IDOFs did not affect motor planning. To differentiate between both cases, a reanalysis of the prior data was conducted. The number of IDOFs in the pointing and grasping tasks was computed by factor analysis. In both tasks, two IDOFs were used, which was the minimum number required for position control. This indicates that hand alignment in the grasping task did not require an additional IDOF. No conclusions regarding the link between the cognitive cost of motor planning and the number of IDOFs could be drawn. A subset of task-critical joint angles was not affected by motor hysteresis. This indicates that a joint's susceptibility to motor hysteresis depends on its relevance to the task goal. In task-critical joints, planning cost minimization by motor plan reuse is suppressed in favor of the task goal.

No Interrelation of Motor Planning and Executive Functions across Young Ages

The present study examined the developmental trajectories of motor planning and executive functioning in children. To this end, we tested 217 participants with three motor tasks, measuring anticipatory planning abilities (i.e., the bar-transport-task, the sword-rotation-task and the grasp-height-task), and three cognitive tasks, measuring executive functions (i.e., the Tower-of-Hanoi-task, the Mosaic-task, and the D2-attention-endurance-task). Children were aged between 3 and 10 years and were separated into age groups by 1-year bins, resulting in a total of eight groups of children and an additional group of adults. Results suggested (1) a positive developmental trajectory for each of the sub-tests, with better task performance as children get older; (2) that the performance in the separate tasks was not correlated across participants in the different age groups; and (3) that there was no relationship between performance in the motor tasks and in the cognitive tasks used in the present study when controlling for age. These results suggest that both, motor planning and executive functions are rather heterogeneous domains of cognitive functioning with fewer interdependencies than often suggested.

Cognitive costs of motor planning do not differ between pointing and grasping in a sequential task

Neurophysiologic studies have shown differences in brain activation between pointing and grasping movements. We asked whether these two movement types would differ in their cognitive costs of motor planning. To this end, we designed a sequential, continuous posture selection task, suitable to investigate pointing and grasping movements to identical target locations. Participants had to open a column of drawers or point to a column of targets in ascending and descending progression. The global hand pro/supination at the moment of drawer/target contact was measured. The size of the motor hysteresis effect, i.e., the persistence to a former posture, was used as a proxy for the cognitive cost of motor planning. A larger hysteresis effect equals higher cognitive cost. Both motor tasks had similar costs of motor planning, but a larger range of motion was found for the grasping movements.

Movement plans for posture selection do not transfer across hands

In a sequential task, the grasp postures people select depend on their movement history. This motor hysteresis effect results from the reuse of former movement plans and reduces the cognitive cost of movement planning. Movement plans for hand trajectories not only transfer across successive trials, but also across hands. We therefore asked whether such a transfer would also be found in movement plans for hand postures. To this end, we designed a sequential, continuous posture selection task. Participants had to open a column of drawers with cylindrical knobs in ascending and descending sequences. A hand switch was required in each sequence. Hand pro/supination was analyzed directly before and after the hand switch. Results showed that hysteresis effects were present directly before, but absent directly after the hand switch. This indicates that, in the current study, movement plans for hand postures only transfer across trials, but not across hands.

The death of recency: Relationship between end-state comfort and serial position effects in serial recall: Logan and Fischman (2011) revisited

Two experiments examined the dynamic interaction between cognitive resources in short-term memory and bimanual object manipulation by extending recent research by Logan and Fischman (2011). In Experiment 1, 16 participants completed a bimanual end-state comfort task and a memory task requiring serial recall of 12 words or pictures. The end-state comfort task involved moving two glasses between two shelves. Participants viewed the items, performed the end-state comfort task, and then serially recalled the items. Recall was evaluated by the presence or absence of primacy and recency effects. The end-state comfort effect (ESCE) was assessed by the percentage of initial hand positions that allowed the hands to end comfortably. The main findings indicated that the ESCE was disrupted; the primacy effect remained intact; and the recency effect disappeared regardless of the type of memory item recalled. In Experiment 2, 16 participants viewed six items, performed an end-state comfort task, viewed another six items, and then serially recalled all 12 items. Results were essentially the same as in Experiment 1. Findings suggest that executing a bimanual end-state comfort task, regardless of when it is completed during a memory task, diminishes the recency effect irrespective of the type of memory item.

Observing end-state comfort favorable actions does not modulate action plan recall

A large corpus of work demonstrates that observing other people’s actions activates corresponding motor representations in the observer by running an internal simulation of the observed action. Recent evidence suggests that recalled action plans reflect a plan of how the observer would execute that action (based on the specific motor representation) rather than a plan of the actually observed action (based on the visual representation). This study examined whether people would recall an action plan based on a visual representation if the observed movement is biomechanically favorable for their own subsequent action. Participants performed an object manipulation task alongside a confederate. In the intra-individual task, the participant (or confederate) transported a plunger from an outer platform of fixed height to a center target platform located at different heights (home-to-target move), and then the same person transported the plunger back to the outer platform (target-back-to-home move). In the inter-individual task, the sequence was split between the two persons such that the participant (or confederate) performed the home-to-target move and the other person performed the target-back-to-home move. Importantly, the confederate always grasped the plunger at the same height. This grasp height was designated such that if participants would copy the action (i.e., grasp the object at the same height) it would place the participant’s arm in a comfortable position at the end of the target-back-to-home move (i.e., end-state comfort). Results show that participants’ grasp height was inversely related to center target height and similar regardless of direction (home-to-target vs. target-back-to-home move) and task (intra- vs. inter-individual). In addition, during the inter-individual task, participant’s target-back-to-home grasp height was correlated with their own, but not with the confederate’s grasp height during the home-to-target moves. These findings provide evidence that observing actions that are biomechanically favorable for subsequent action execution does not influence action plan recall processes.

Limits of end-state planning

The end-state comfort effect is the tendency to use an uncomfortable initial grasp posture for object manipulation if this leads to a comfortable final posture. Many studies have replicated the end-state comfort effect across a range of tasks and conditions. However, these tasks had in common that they involved relatively simple movements, such as picking up a dowel or sliding a pan from one place to another. Here we asked whether the end-state comfort effect extends to more complex tasks. We asked participants to grasp a transparent bowl and move the bowl to an instructed location, positioning it in an instructed orientation. We either found an initial-state comfort effect or equal degrees of comfort for end-grasps and start-grasps depending on task instructions. The end-state comfort effect was not consistently observed. The results suggest that the end-state comfort effect may be restricted to relatively simple grasping movements.

Hysteresis as an implicit prior in tactile spatial decision making

Perceptual decisions not only depend on the incoming information from sensory systems but constitute a combination of current sensory evidence and internally accumulated information from past encounters. Although recent evidence emphasizes the fundamental role of prior knowledge for perceptual decision making, only few studies have quantified the relevance of such priors on perceptual decisions and examined their interplay with other decision-relevant factors, such as the stimulus properties. In the present study we asked whether hysteresis, describing the stability of a percept despite a change in stimulus property and known to occur at perceptual thresholds, also acts as a form of an implicit prior in tactile spatial decision making, supporting the stability of a decision across successively presented random stimuli (i.e., decision hysteresis). We applied a variant of the classical 2-point discrimination task and found that hysteresis influenced perceptual decision making: Participants were more likely to decide ‘same’ rather than ‘different’ on successively presented pin distances. In a direct comparison between the influence of applied pin distances (explicit stimulus property) and hysteresis, we found that on average, stimulus property explained significantly more variance of participants’ decisions than hysteresis. However, when focusing on pin distances at threshold, we found a trend for hysteresis to explain more variance. Furthermore, the less variance was explained by the pin distance on a given decision, the more variance was explained by hysteresis, and vice versa. Our findings suggest that hysteresis acts as an implicit prior in tactile spatial decision making that becomes increasingly important when explicit stimulus properties provide decreasing evidence.

Whole-body posture planning in anticipation of a manual prehension task: prospective and retrospective effects

This study examined the extent to which the anticipation of a manual action task influences whole-body postural planning and orientation. Our participants walked up to a drawer, opened the drawer, then grasped and moved an object in the drawer to another location in the same drawer. The starting placement of the object within the drawer and the final placement of the object in the drawer were varied across trials in either a blocked design (i.e., in trials where the same start and end location were repeated consecutively) or in a mixed fashion. Of primary interest was the posture adopted at the moment of grasping the drawer handle before pulling it out prior to the object manipulation task. Of secondary interest was whether there were sequential effects such that postures adopted in preceding trials influenced postures in subsequent trials. The results indicated that the spatial properties of the forthcoming object manipulation influenced both the postures adopted by the participants and the degree to which the drawer was opened, suggesting a prospective effect. In addition, the adopted postures were more consistent in blocked trials than in mixed trials, suggesting an additional retrospective effect. Overall, our findings suggest that motor planning occurs at the level of the whole body, and reflects both prospective and retrospective influences.

The context dependence of grasping movements: an evaluation of possible reasons

Laboratory experiments typically examine grasping movements as isolated motor acts executed for their own sake. In real life, however, grasping is often part of complex and meaningful movement sequences. We have shown before that grasping characteristics differ substantially between these two behavioral contexts and that these differences can be reduced to five orthogonal factors. Now we evaluate the role of focused attention, movement speed and/or embedding in other behavior as possible causes for the observed context differences. Subjects grasped in three variants, which deviated from our standard laboratory condition in one of the above three ways: In one, subjects' attention was withdrawn from grasping by a concurrent visual memory task; in a second, subjects were pre-trained to grasp as slowly as in our standard everyday-like condition; and in the third variant, grasping was part of a more complex behavioral sequence. Grasping kinematics, grip forces and eye movements were registered across 20 repetitions of each variant, the outcome was normalized with respect to our standard laboratory and standard everyday-like conditions, and the normalized data were reduced to the underlying orthogonal factors. We found that the three variants of the laboratory condition had a non-uniform effect on grasping: decreasing the difference to the standard everyday-like condition for some factors, increasing it for others and leaving it unchanged for yet others. We interpret this finding as evidence that none of the three variants successfully reduced the difference between standard laboratory and standard everyday-like context; differences between contexts are therefore probably related to factors other than focusing of attention, movement speed and embedding in other behavior.

Optimal control in the critical phase of movement: a functional approach to motor planning processes

Grasping movements are often planned in a way that they end in a position where joints are in an anatomically medial position. This behaviour is termed the "end-state comfort" (ESC) effect (Rosenbaum et al., 1990). We suggest that the anatomically medial position is favoured to control the most difficult part of the movement. In most experiments investigating ESC, objects have to be placed onto a target location, and the highest precision demand occurs at the end of the movement. Thus, ESC is confounded with movement difficulty. In this study, we dissociate movement difficulty and ESC. In our experiments, participants had to execute a task where the critical part of the movement was either at the end or at the beginning of the movement. Participants' grasping behaviour confirmed the hypothesis that movement planning is constrained by a goal for optimal control during the part of the movement that demands the highest precision, rather than by a goal to end in a comfortable state (Rosenbaum, Chapman, Weigelt, Weiss, & van der Wel, 2012). We identified recall and movement plan generating processes of motor planning (Cohen & Rosenbaum, 2004), that ensure the optimal control in the critical part of movement. Our results indicate that recall processes depend on motor experience which is acquired in different time scales. We suggest that motor planning processes are triggered only if the costs for executing movements controlled by recall processes exceed the costs for generating a motor plan.