Response Demands and Blindfolding in the Crossed-Hands Deficit: An Exploration of Reference Frame Conflict

2013 ◽  
Vol 26 (5) ◽  
pp. 465-482 ◽  
Author(s):  
Michelle L. Cadieux ◽  
David I. Shore

Performance on tactile temporal order judgments (TOJs) is impaired when the hands are crossed over the midline. The cause of this effect appears to be tied to the use of an external reference frame, most likely based on visual information. We measured the effect of degrading the external reference frame on the crossed-hand deficit through restriction of visual information across three experiments. Experiments 1 and 2 examined three visual conditions (eyes open–lights on, eyes open–lights off, and eyes closed–lights off) while manipulating response demands; no effect of visual condition was seen. In Experiment 3, response demands were altered to be maximally connected to the internal reference frame and only two visual conditions were tested: eyes open–lights on, eyes closed–lights off. Blindfolded participants had a reduced crossed-hands deficit. Results are discussed in terms of the time needed to recode stimuli from an internal to an external reference frame and the role of conflict between these two reference frames in causing this effect.

2021 ◽  
pp. 1-29
Author(s):  
Lisa Lorentz ◽  
Kaian Unwalla ◽  
David I. Shore

Abstract Successful interaction with our environment requires accurate tactile localization. Although we seem to localize tactile stimuli effortlessly, the processes underlying this ability are complex. This is evidenced by the crossed-hands deficit, in which tactile localization performance suffers when the hands are crossed. The deficit results from the conflict between an internal reference frame, based in somatotopic coordinates, and an external reference frame, based in external spatial coordinates. Previous evidence in favour of the integration model employed manipulations to the external reference frame (e.g., blindfolding participants), which reduced the deficit by reducing conflict between the two reference frames. The present study extends this finding by asking blindfolded participants to visually imagine their crossed arms as uncrossed. This imagery manipulation further decreased the magnitude of the crossed-hands deficit by bringing information in the two reference frames into alignment. This imagery manipulation differentially affected males and females, which was consistent with the previously observed sex difference in this effect: females tend to show a larger crossed-hands deficit than males and females were more impacted by the imagery manipulation. Results are discussed in terms of the integration model of the crossed-hands deficit.


2021 ◽  
pp. 1-32
Author(s):  
Kaian Unwalla ◽  
Daniel Goldreich ◽  
David I. Shore

Abstract Exploring the world through touch requires the integration of internal (e.g., anatomical) and external (e.g., spatial) reference frames — you only know what you touch when you know where your hands are in space. The deficit observed in tactile temporal-order judgements when the hands are crossed over the midline provides one tool to explore this integration. We used foot pedals and required participants to focus on either the hand that was stimulated first (an anatomical bias condition) or the location of the hand that was stimulated first (a spatiotopic bias condition). Spatiotopic-based responses produce a larger crossed-hands deficit, presumably by focusing observers on the external reference frame. In contrast, anatomical-based responses focus the observer on the internal reference frame and produce a smaller deficit. This manipulation thus provides evidence that observers can change the relative weight given to each reference frame. We quantify this effect using a probabilistic model that produces a population estimate of the relative weight given to each reference frame. We show that a spatiotopic bias can result in either a larger external weight (Experiment 1) or a smaller internal weight (Experiment 2) and provide an explanation of when each one would occur.


2001 ◽  
Vol 49 (3-10) ◽  
pp. 111-121 ◽  
Author(s):  
Joseph McIntyre ◽  
Mark Lipshits ◽  
Mohamed Zaoui ◽  
Alain Berthoz ◽  
Victor Gurfinkel

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kaian Unwalla ◽  
Michelle L. Cadieux ◽  
David I. Shore

AbstractAccurate localization of touch requires the integration of two reference frames—an internal (e.g., anatomical) and an external (e.g., spatial). Using a tactile temporal order judgement task with the hands crossed over the midline, we investigated the integration of these two reference frames. We manipulated the reliability of the visual and vestibular information, both of which contribute to the external reference frame. Visual information was manipulated between experiments (Experiment 1 was done with full vision and Experiment 2 was done while wearing a blindfold). Vestibular information was manipulated in both experiments by having the two groups of participants complete the task in both an upright posture and one where they were lying down on their side. Using a Bayesian hierarchical model, we estimated the perceptual weight applied to these reference frames. Lying participants on their side reduced the weight applied to the external reference frame and produced a smaller deficit; blindfolding resulted in similar reductions. These findings reinforce the importance of the visual system when weighting tactile reference frames, and highlight the importance of the vestibular system in this integration.


2006 ◽  
Vol 96 (1) ◽  
pp. 352-362 ◽  
Author(s):  
Sabine M. Beurze ◽  
Stan Van Pelt ◽  
W. Pieter Medendorp

At some stage in the process of a sensorimotor transformation for a reaching movement, information about the current position of the hand and information about the location of the target must be encoded in the same frame of reference to compute the hand-to-target difference vector. Two main hypotheses have been proposed regarding this reference frame: an eye-centered and a body-centered frame. Here we evaluated these hypotheses using the pointing errors that subjects made when planning and executing arm movements to memorized targets starting from various initial hand positions while keeping gaze fixed in various directions. One group of subjects ( n = 10) was tested without visual information about hand position during movement planning (unseen-hand condition); another group ( n = 8) was tested with hand and target position simultaneously visible before movement onset (seen-hand condition). We found that both initial hand position and gaze fixation direction had a significant effect on the magnitude and direction of the pointing error. Errors were significantly smaller in the seen-hand condition. For both conditions, though, a reference frame analysis showed that the errors arose at an eye- or hand-centered stage or both, but not at a body-centered stage. As a common reference frame is required to specify a movement vector, these results suggest that an eye-centered mechanism is involved in integrating target and hand position in programming reaching movements. We discuss how simple gain elements modulating the eye-centered target and hand-position signals can account for these results.


2004 ◽  
Vol 21 (1) ◽  
pp. 19-33 ◽  
Author(s):  
Eryk P. Przysucha ◽  
M. Jane Taylor

The purpose of this study was to compare the postural sway profiles of 20 boys with and without Developmental Coordination Disorder (DCD) on two conditions of a quiet standing task: eyes open and eyes closed. Anterior-posterior (AP) sway, medio-lateral sway (LAT), area of sway, total path length, and Romberg’s quotient were analyzed. When visual information was available, there was no difference between groups in LAT sway or path length. However, boys with DCD demonstrated more AP sway (p < .01) and greater area of sway (p < .03), which resulted in pronounced excursions closer to their stability limits. Analysis of Romberg’s quotient indicated that boys with DCD did not over-rely on visual information.


Sports ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 89
Author(s):  
Albina Andreeva ◽  
Andrey Melnikov ◽  
Dmitry Skvortsov ◽  
Kadriya Akhmerova ◽  
Alexander Vavaev ◽  
...  

The effects of different factors—such as age, sex, performance level, and athletic shoe features—on postural balance in athletes remain unclear. The main objective of our study is to identify the features of postural stability in athletes of different age, sex, performance level, and using different types of athletic shoes. This study assessed postural stability in athletes (n = 936, 6–47 years) in a normal bipedal stance with eyes open (EO) and eyes closed (EC). Postural stability was evaluated based on the center of pressure (COP), sway area (AS), and velocity (VCP) while standing on a stabiloplatform. Children (6–12 years) and teen athletes (13–17 years) showed reduced AS-EO (p < 0.01) and VCP-EO (p < 0.01) compared to control (n = 225, 7–30 years). In male and female athletes aged 18+, only VCP-EC was lower versus control. In females (13–17 and 18+), VCP-EO and EC were lower than in males (p < 0.05). Only in the Shooting group, the athletes’ performance levels had an effect on VCP-EO (p = 0.020). Long use of rigid athletic shoes with stiff ankle support was associated with reduced posture stability. Postural stability in athletes was mostly influenced by the athlete‘s age, and, to a lesser extent, by their sex, performance level, and athlete shoe features.


2012 ◽  
Vol 25 (0) ◽  
pp. 144
Author(s):  
Rebecca Lawson ◽  
Lauren Edwards ◽  
Amy Boylan

As we explore objects by touch we usually look towards our hands. Active touch (haptics) may therefore benefit from the simultaneous availability of visual information about the object that we are feeling and the alignment of spatial frames of reference centred on our head, eye and hand. If haptic processing usually uses visual and spatial inputs then even task-irrelevant visual and spatial manipulations may influence haptic shape identification. Scocchia et al. (2009) found that recognition of raised line pictures of familiar objects was better if people looked towards the pictures as they felt them although people were blindfolded so could not see their hand or the picture. We replicated their finding for 2D pictures and extended it to 3D, small-scale models of familiar objects. We also tested people’s speeded naming of real, familiar objects using their right hand. Performance was better when people looked towards the objects. In contrast, the position of the left hand did not influence haptic naming. Thus the spatial reference frame defined by the eyes/head influenced haptic shape processing but not that defined by an inactive hand. Furthermore, performance was the same whether people wore a mask and had their eyes closed, wore a mask but had their eyes open or looked through a narrow tube so could see a small area of their environment but not their hand or the object. Thus where people looked had a small but reliable effect on haptic object recognition but not what task-irrelevant information they could see.


2012 ◽  
Vol 25 (0) ◽  
pp. 18
Author(s):  
Achille Pasqualotto

How do people remember the location of objects? Location is always relative, and thus depends on a reference frame. There are two types of reference frames: egocentric (or observer-based) and allocentric (or environmental-based). Here we investigated the reference frame people used to remember object locations in a large room. We also examined whether the choice of a given reference frame is dictated by visual experience. Thus we tested congenitally blind, late blind, and sighted blindfolded participants. Objects were organized in a structured configuration and then explored one-by-one with participants walking back and forth from a single point. After the exploration of the locations, a spatial memory test was conducted. The memory test required participants to imagine being inside the array of objects, being oriented along a given heading, and then pointing towards the required object. Crucially the headings were either aligned to the allocentric structure of the configuration, that is rows and columns, or aligned to the egocentric route walked during the exploration of the objects. The spatial representation used by the participants can be revealed by better performance when the imagined heading in the test matches the spatial representation used. We found that participants with visual experience, that is late blind and blindfolded sighted, were better with headings aligned to the allocentric structure of the configuration. On the contrary, congenitally blind were more accurate with headings aligned to the egocentric walked routes. This suggests that visual experience during early development determines a preference for an allocentric frame of reference.


2013 ◽  
Vol 103 (4) ◽  
pp. 291-296 ◽  
Author(s):  
Shirley S. M. Fong ◽  
Shamay S. M. Ng

Background: This study aims to investigate the effect of taekwondo footwear on unilateral stance stability and use of postural control strategies and to determine whether taekwondo footwear influences the somatosensory inputs for postural stability and postural strategies in young adults. Methods: A quasi-randomized crossover trial was conducted on 33 healthy young adults at a university research laboratory. Independent variables, including shoe conditions (shoes on and shoes off) and visual conditions (eyes open and eyes closed), were taken into account. The center of gravity (COG) sway velocity in unilateral stance and the strategy scores in the sensory organization test were measured. No intervention was given to the participants. Results: There was no significant interaction between the two factors (the shoe and visual conditions) for COG sway velocities (P = .447) and strategy scores (P = .320). The shoe condition was not significant in either COG sway velocity (P = .484) or strategy score (P = .126). The visual condition was significant for COG sway velocity (P &lt; .001) but not for strategy score (P = .573). The mean ± SD COG sway velocity with eyes open was 0.7° ± 0.2°/sec and with eyes closed was 1.7° ± 0.6°/sec (P &lt; .001). Conclusions: Taekwondo footwear is unlikely to affect somatosensory inputs and balance performance in young adults. (J Am Podiatr Med Assoc 103(4): 291–296, 2013)


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