71 research outputs found

    Perceptual control of interceptive timing

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    Early motor trajectories predict motor but not cognitive function in preterm- and term-born adults without pre-existing neurological conditions

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    Very preterm (VP; 0.05). Motor problems in childhood were homotypically associated with poorer motor competence in adulthood. Similarly, early cognitive problems were homotypically associated with adult cognitive outcomes. Thus, both motor and cognitive function should be assessed in routine follow-up during childhood

    Triggering prepared actions by sudden sounds : reassessing the evidence for a single mechanism

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    Loud acoustic stimuli can unintentionally elicit volitional acts when a person is in a state of readiness to execute them (the StartReact effect). It has been assumed that the same subcortical pathways and brain regions underlie all instances of the StartReact effect. They are proposed to involve the startle reflex pathways, and the eliciting mechanism is distinct from other ways in which sound can affect the motor system. We present an integrative review which shows that there is no evidence to support these assumptions. We argue that motor command generation for learned, volitional orofacial, laryngeal and distal limb movements is cortical and the StartReact effect for such movements involves transcortical pathways. In contrast, command generation for saccades, locomotor corrections and postural adjustments is subcortical and subcortical pathways are implicated in the StartReact effect for these cases. We conclude that the StartReact effect is not a special phenomenon mediated by startle reflex pathways, but rather is a particular manifestation of the excitatory effects of intense stimulation on the central nervous system

    Delayed inhibition of an anticipatory action during motion extrapolation

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    Background: Continuous visual information is important for movement initiation in a variety of motor tasks. However, even in the absence of visual information people are able to initiate their responses by using motion extrapolation processes. Initiation of actions based on these cognitive processes, however, can demand more attentional resources than that required in situations in which visual information is uninterrupted. In the experiment reported we sought to determine whether the absence of visual information would affect the latency to inhibit an anticipatory action. Methods: The participants performed an anticipatory timing task where they were instructed to move in synchrony with the arrival of a moving object at a determined contact point. On 50% of the trials, a stop sign appeared on the screen and it served as a signal for the participants to halt their movements. They performed the anticipatory task under two different viewing conditions: Full-View (uninterrupted) and Occluded-View (occlusion of the last 500 ms prior to the arrival at the contact point). Results: The results indicated that the absence of visual information prolonged the latency to suppress the anticipatory movement. Conclusion: We suggest that the absence of visual information requires additional cortical processing that creates competing demand for neural resources. Reduced neural resources potentially causes increased reaction time to the inhibitory input or increased time estimation variability, which in combination would account for prolonged latency

    Grasping at laws:Speed-accuracy trade-offs in manual prehension

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    Most of human performance is subject to speed-accuracy trade-offs. For spatially constrained aiming, the trade-off is often said to take the specific form of Fitts' law, in which movement duration is predicted from a single factor combining target distance and target size. However, efforts to extend this law to the three-dimensional context of reaching to grasp (prehension) have had limited success. We suggest that there are potentially confounding influences in standard grasping, and we introduce a novel task to regularize the direction of approach and to eliminate the influences of nearby surfaces. In six participants, we examined speed-accuracy trade-offs for prehension, manipulating the depth (in the plane of the reach), height (orthogonal to the reach), and width (the grasped dimension) of the target object independently. We obtained lawful relationships that were consistent at the group and individual levels. It took longer to reach for more distant objects, and more time was allowed when placing the fingers on a contact surface smaller in either depth or height. More time was taken to grasp wider objects, but only beyond a critical width that varied between individuals. These speed-accuracy trade-offs showed substantial departures from Fitts' law, and were well described by a two-factor model in which reach distance and object size have separate influences on movement duration. We discuss empirical and theoretical reasons for preferring a two-factor model, and we propose that this may represent the most general form of speed-accuracy trade-off, not only for grasping but also for other spatially constrained aiming tasks. (PsycINFO Database Record [Abstract copyright: (c) 2018 APA, all rights reserved).

    Predictors of early motor trajectories from birth to 5 years in neonatal at-risk and control children

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    Aim To describe motor development in preschool children, to identify perinatal, neonatal and social environmental risk factors of poor motor development, and to replicate results in a second cohort. Methods Two prospective samples in Germany (Bavarian Longitudinal Study, BLS) and Finland (Arvo Ylppo Longitudinal Study, AYLS) assessed 4741 and 1423 children from birth to 56 months, respectively. Motor functioning was evaluated at birth, and 5, 20 and 56 months. Perinatal, neonatal and social environmental information was collected at birth and 5 months. Results Two distinct motor trajectories were identified: low (BLS: n = 4486 (94.6%), AYLS: n = 1391 (97.8%)) and high (BLS: n = 255 (5.4%), AYLS: n = 32 (2.2%)) degree of motor difficulties. High degree of motor difficulties was predicted by neonatal complications, abnormal neonatal neurological status, duration of hospitalisation and poor parent-infant relationships. Although neonatal complications and poor parent-infant relationships did not significantly predict high degree of motor difficulties in the AYLS, the trends identified were similar to those obtained from the BLS. Conclusion Early identification of children at-risk of motor difficulties across infancy and toddlerhood may help referring those children to interventions earlier. Modifiable risk factors, such as parent-infant relationships, may be addressed by intervention strategies to prevent children from developing motor difficulties.Peer reviewe

    Effects of infant motor problems and treatment with physiotherapy on child outcomes at school-age

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    Background: Early motor coordination problems have previously been associated with various developmental outcomes at school-age. Aims: Investigate whether and how treatment with physiotherapy may alter associations between early motor problems and subsequent developmental outcomes. Study design: A prospective whole-population study. Subjects: 1374 children were followed from birth to 8 years. Outcome measures: Early motor functioning was determined with standard neurological examinations at birth and at 5 months. Information on receipt of physiotherapy was collected through parent interviews at 5, 20 and 56 months. Developmental outcomes at 6 and 8 years included motor skills, mental health, cognitive function, and attention regulation and were determined through standard tests, parent reports and observed behavior ratings. Results: Early motor problems were associated with lower motor skills, cognitive function, and attention regulation at school-age, but not with mental health. In addition to early motor problems, receipt of physiotherapy was independently and negatively related to outcomes at school-age. Accounting for imbalances in covariates, including initial motor scores, via propensity score matching attenuated the adverse effects of receipt of physiotherapy on school-aged outcomes. Conclusions: Infant motor problems are associated with motor and cognitive outcomes at school-age. Early motor problems may represent a starting point of a trajectory of difficulties that may lead to a higher risk of problems in multiple developmental domains. No evidence for a beneficial effect of treatment with physiotherapy was found

    Radical predictive processing

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    Recent work in computational and cognitive neuroscience depicts the brain as an ever‐active prediction machine: an inner engine continuously striving to anticipate the incoming sensory barrage. I briefly introduce this class of models before contrasting two ways of understanding the implied vision of mind. One way (Conservative Predictive Processing) depicts the predictive mind as an insulated inner arena populated by representations so rich and reconstructive as to enable the organism to ‘throw away the world’. The other (Radical Predictive Processing) stresses the use of fast and frugal, action‐involving solutions of the kind highlighted by much work in robotics and embodied cognition. But it goes further, by showing how predictive schemes can combine frugal and more knowledge‐intensive strategies, switching between them fluently and continuously as task and context dictate. I end by exploring some parallels with work in enactivism, and by noting a certain ambivalence concerning internal representations and their role in the predictive mind

    How you feel: the story of the mind as told by the body

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    You might feel thirsty or tired. You might feel healthy and well or perhaps a little under the weather. Maybe you can feel that you are standing or that you are leaning over. You may also feel the world around you - the shape and texture of an apple in your hand, the feel of a chair you're sitting on.All these feelings have something in common, say psychologists and neuroscientists. They are all mental events, things that happen in the mind. But what if this is all wrong?What if it's not just the mind, but also the body itself that feels? And not merely physical sensations, but other feelings that seem to have nothing to do with bodies. Things like 'emotions' and 'intuitions' - joy or rage, anxiety or optimism, or the feeling of being hard done by or misunderstood?Drawing on the latest research and a range of classic and contemporary thought, How You Feel shows you that your brain and your body are two parts of a single system that creates your mind and mental life. You will discover that you don't have feelings, thoughts and emotions inside your body, you have them with your body. There can be no mind without the body.Psychology is no longer about the brain, or about 'mind and body', it is about the whole that is you.280 hl

    Visually timed action: Time-out for tau?

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    Bringing about desirable collisions (making interceptions) and avoiding unwanted collisions are critically important sensorimotor skills, which appear to require us to estimate the time remaining before collision occurs (time-to-collision). Until recently the theoretical approach to understanding time-to-collision estimation has been dominated by the tau-hypothesis, which has its origins in J.J. Gibson’s ecological approach to perception. The hypothesis proposes that a quantity (tau), present in the visual stimulus, provides the necessary time-to-collision information. Empirical results and formal analyses have now accumulated to demonstrate conclusively that the tau-hypothesis is false. This article describes an alternative approach that is based on recent data showing that the information used in judging time-to-collision is task- and situation-dependent, is of many different origins (of which tau is just one) and is influenced by the information-processing constraints of the nervous system
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