Abstract:Human veering while walking blindfolded or walking straight without any visual cues has been widely studied over the last 100 years, but the results are still controversial. The present study attempted to describe and understand the human ability to maintain the direction of a trajectory while walking without visual or audio cues with reference to a proposed mathematical model and using data collected by a global positioning system (GPS). Fifteen right-handed people of both genders, aged 18-30 years, walked wi… Show more
“…However, there was no significant difference in preference for right and left orientation when considering the overall trials, but substantial within-subject variability and between-subject variability from trial to trial were observed (Bestaven et al, 2012). The findings of the previous three studies have been corroborated by the findings of a very recent study that examined veering behavior in right-handed humans but under different experimental conditions (Consolo, Holanda, & Fukusima, 2014), In this study, participants were allowed to see the target for a brief period of time, then blindfolded, and asked to walk without any visual or auditory cues in an open field directly toward the target. This study demonstrated that irrespective the target distance, the most frequently used pattern was the circular trajectory.…”
Section: Directionality Bias In Turning or Rotational Behaviorsupporting
confidence: 70%
“…In such a situation people probably find themselves rendered helpless, which cause them either to stay (if not asked to walk/move) or to walk/move (if asked to do) in circles around their current standing positions (possibly within a short range of distance) rather than getting lost by walking toward an uncertain distant goal or target. However, researchers have suggested that this nature of veering can be caused by vestibular function (Consolo et al, 2014) rather than DA imbalance in the brain (Mohr & Lievesley, 2007). …”
Section: Directionality Bias In Turning or Rotational Behaviormentioning
Reviewing the relevant literature in visual psychophysics and visual neuroscience we propose a three-stage model of directionality bias in visuospatial functioning. We call this model the ‘Perception-Action-Laterality’ (PAL) hypothesis. We analyzed the research findings for a wide range of visuospatial tasks, showing that there are two major directionality trends: clockwise versus anticlockwise. It appears these preferences are combinatorial, such that a majority of people fall in the first category demonstrating a preference for stimuli/objects arranged from left-to-right rather than from right-to-left, while people in the second category show an opposite trend. These perceptual biases can guide sensorimotor integration and action, creating two corresponding turner groups in the population. In support of PAL, we propose another model explaining the origins of the biases– how the neurogenetic factors and the cultural factors interact in a biased competition framework to determine the direction and extent of biases. This dynamic model can explain not only the two major categories of biases, but also the unbiased, unreliably biased or mildly biased cases in visuosptial functioning.
“…However, there was no significant difference in preference for right and left orientation when considering the overall trials, but substantial within-subject variability and between-subject variability from trial to trial were observed (Bestaven et al, 2012). The findings of the previous three studies have been corroborated by the findings of a very recent study that examined veering behavior in right-handed humans but under different experimental conditions (Consolo, Holanda, & Fukusima, 2014), In this study, participants were allowed to see the target for a brief period of time, then blindfolded, and asked to walk without any visual or auditory cues in an open field directly toward the target. This study demonstrated that irrespective the target distance, the most frequently used pattern was the circular trajectory.…”
Section: Directionality Bias In Turning or Rotational Behaviorsupporting
confidence: 70%
“…In such a situation people probably find themselves rendered helpless, which cause them either to stay (if not asked to walk/move) or to walk/move (if asked to do) in circles around their current standing positions (possibly within a short range of distance) rather than getting lost by walking toward an uncertain distant goal or target. However, researchers have suggested that this nature of veering can be caused by vestibular function (Consolo et al, 2014) rather than DA imbalance in the brain (Mohr & Lievesley, 2007). …”
Section: Directionality Bias In Turning or Rotational Behaviormentioning
Reviewing the relevant literature in visual psychophysics and visual neuroscience we propose a three-stage model of directionality bias in visuospatial functioning. We call this model the ‘Perception-Action-Laterality’ (PAL) hypothesis. We analyzed the research findings for a wide range of visuospatial tasks, showing that there are two major directionality trends: clockwise versus anticlockwise. It appears these preferences are combinatorial, such that a majority of people fall in the first category demonstrating a preference for stimuli/objects arranged from left-to-right rather than from right-to-left, while people in the second category show an opposite trend. These perceptual biases can guide sensorimotor integration and action, creating two corresponding turner groups in the population. In support of PAL, we propose another model explaining the origins of the biases– how the neurogenetic factors and the cultural factors interact in a biased competition framework to determine the direction and extent of biases. This dynamic model can explain not only the two major categories of biases, but also the unbiased, unreliably biased or mildly biased cases in visuosptial functioning.
“…When executing a goal-directed trajectory in the absence of landmarks, humans rely on path integration (the integration of self-motion cues to determine the position and heading) and an internal representation of the environment [9, 33]. However, path-integration without the correction from external directional references is prone to accumulating noise resulting in increasing positional and heading errors throughout the trajectory [13, 56] (see Figure 2A). Similarly, noise in observation (see Figure 2B) and representation (see Figure 2C) lead to variability in endpoints even in the absence of errors caused by noisy motor actions.…”
Section: Resultsmentioning
confidence: 99%
“…Beyond being able to capture and explain empirical data from multiple triangle completion tasks, including behavior considered contradictory under ideal observer models, the dynamic Bayesian actor model allows to reconcile previous accounts of navigation in a coherent computational framework. The present model includes perception [8], representation [33], planning [65] and execution of motor actions [12,13,56], while considering uncertainty, which allows predicting and explaining how these seemingly separate processes interact in producing observed navigation behavior in triangle completion task. The homing task with landmarks has been described as comprising several different 'navigational strategies' while the task unfolds.…”
Section: Relation To Other Experimental Workmentioning
Goal-directed navigation requires integrating information from a variety of internal and external spatial cues, representing them internally, planning, and executing motor actions sequentially. However, a comprehensive computational account of how these processes interact in an ambiguous, uncertain, and noisy environment giving rise to biases and variability observed in navigation behavior is currently unavailable. In this paper, we introduce an optimal control under uncertainty model, which provides a computational-level explanation of how landmarks and path integration interact and are combined to reduce variability in navigation. We apply our model to trajectory and end-point data from three previously published studies that employ a variant of the triangle completion task with landmarks. Contrary to observer models, which attribute human endpoint variability to perceptual cue combination processes only, this dynamic Bayesian actor model provides a unifying account of a wide range of phenomena found in this task by considering variability in perception, action, and internal representations jointly. Taken together, these findings have wide-ranging implications for the analysis and interpretation of human navigation behavior, including resolution of seemingly contradictory results on cue integration in navigation.
“…However, poor correlations exist between leg length difference, handedness, or lateral preference, while head posture increases the error [ 2 – 4 ]. This suggests a role for the neck proprioceptive or vestibular input in stabilizing the stepping orientation [ 5 , 6 ].…”
Unilateral axial muscle vibration, eliciting a proprioceptive volley, is known to incite steering behavior. Whole-body rotation while stepping in place also occurs as an after-effect of stepping on a circular treadmill (podokinetic after-rotation, PKAR). Here, we tested the hypothesis that PKAR is modulated by axial muscle vibration. If both phenomena operate through a common pathway, enhancement or cancellation of body rotation would occur depending on the stimulated side when vibration is administered concurrently with PKAR. Seventeen subjects participated in the study. In one session, subjects stepped in place eyes open on the center of a platform that rotated counterclockwise 60°/s for 10 min. When the platform stopped, subjects continued stepping in place blindfolded. In other session, a vibratory stimulus (100 Hz, 2 min) was administered to right or left paravertebral muscles at lumbar level at two intervals during the PKAR. We computed angular body velocity and foot step angles from markers fixed to shoulders and feet. During PKAR, all subjects rotated clockwise. Decreased angular velocity was induced by right vibration. Conversely, when vibration was administered to the left, clockwise rotation velocity increased. The combined effect on body rotation depended on the time at which vibration was administered during PKAR. Under all conditions, foot step angle was coherent with shoulder angular velocity. PKAR results from continuous asymmetric input from the muscles producing leg rotation, while axial muscle vibration elicits a proprioceptive asymmetric input. Both conditioning procedures appear to produce their effects through a common mechanism. We suggest that both stimulations would affect our straight ahead by combining their effects in an algebraic mode.
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