Delays in Admittance-Controlled Haptic Devices Make Simulated Masses Feel Heavier

Journal of Neurophysiology

Sulimani

Mussa-Ivaldi

et al. 2019

The sensory system constantly deals with delayed feedback. Recent studies showed that playing a virtual game of pong with delayed feedback caused hypermetric reaching movements. We investigated whether this effect is associated with a perceptual bias. In addition, we examined the importance of the target in causing hypermetric movements. In a first experiment, participants played a delayed pong game and blindly reached to presented targets. Following each reaching movement, they assessed the position of the invisible cursor. We found that participants performed hypermetric movements but reported that the invisible cursor reached the target, suggesting that they were unaware of the hypermetria and that their perception was biased toward the target rather than toward their hand position. In a second experiment, we removed the visual target, and strikingly, the hypermetria vanished. Moreover, participants reported that the invisible cursor was located with their hand. Taking these results together, we conclude that the adaptation to the visuomotor delay during the pong game selectively affected the execution of goal directed movements, resulting in hypermetria and perceptual bias when movements are directed toward visual targets but not when such targets are absent. NEW & NOTEWORTHY Recent studies showed that adaptation to visuomotor delays causes hypermetric movements in the absence of visual feedback, suggesting that visuomotor delay is represented using current state information. We report that this adaptation also affects perception. Importantly, both the motor and perceptual effects are selective to the representations that are used in the execution of goal-directed movements toward visual targets.

Section: Introductionmentioning

confidence: 99%

Effects of visuomotor delays on the control of movement and on perceptual localization in the presence and absence of visual targets

Journal of Neurophysiology

Sulimani

Mussa-Ivaldi

et al. 2019

“…Humans can adapt to visuomotor delays (Miall and Jackson, 2006; Botzer and Karniel, 2013) and delayed force feedback (Witney et al 1999; Levy et al 2010; Leib et al 2015; Avraham et al 2017). However, delayed feedback biases perception of impedance (Pressman et al 2007; Nisky et al 2008, 2010; Di Luca et al 2011; Kuling et al 2015; Takamuku and Gomi, 2015; Leib et al 2016), suggesting that the sensorimotor system has limited capability to realign the signals for accurate estimations of the environment (Ionta et al 2014). …”

Section: Introductionmentioning

confidence: 99%

State-Based Delay Representation and Its Transfer from a Game of Pong to Reaching and Tracking

Leib

Pressman

et al. 2017

eNeuro

To accurately estimate the state of the body, the nervous system needs to account for delays between signals from different sensory modalities. To investigate how such delays may be represented in the sensorimotor system, we asked human participants to play a virtual pong game in which the movement of the virtual paddle was delayed with respect to their hand movement. We tested the representation of this new mapping between the hand and the delayed paddle by examining transfer of adaptation to blind reaching and blind tracking tasks. These blind tasks enabled to capture the representation in feedforward mechanisms of movement control. A Time Representation of the delay is an estimation of the actual time lag between hand and paddle movements. A State Representation is a representation of delay using current state variables: the distance between the paddle and the ball originating from the delay may be considered as a spatial shift; the low sensitivity in the response of the paddle may be interpreted as a minifying gain; and the lag may be attributed to a mechanical resistance that influences paddle’s movement. We found that the effects of prolonged exposure to the delayed feedback transferred to blind reaching and tracking tasks and caused participants to exhibit hypermetric movements. These results, together with simulations of our representation models, suggest that delay is not represented based on time, but rather as a spatial gain change in visuomotor mapping.

“…Humans can adapt to visuomotor delays (Miall and Jackson, 2006;Botzer and Karniel, 2013) and to delayed force feedback (Witney et al, 1999;Levy et al, 2010;Leib et al, 2015;Avraham et al, 2017). However, delayed feedback biases perception of impedance (Pressman et al, 2007;Nisky et al, 2008;Nisky et al, 2010;Di Luca et al, 2011;Kuling et al, 2015;Takamuku and Gomi, 2015;Leib et al, 2016), suggesting that the sensorimotor system has limited capability to realign the signals for accurate estimations of the environment (Ionta et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

State-Based Delay Representation and Its Transfer from a Game of Pong to Reaching and Tracking

Leib

Pressman

et al. 2017

Preprint

To accurately estimate the state of the body, the nervous system needs to account for delays between signals from different sensory modalities. To investigate how such delays may be represented in the sensorimotor system, we asked human participants to play a virtual pong game in which the movement of the virtual paddle was delayed with respect to their hand movement. We tested the representation of this new mapping between the hand and the delayed paddle by examining transfer of adaptation to blind reaching and blind tracking tasks.These blind tasks enabled to capture the representation in feedforward mechanisms of movement control. A Time Representation of the delay is an estimation of the actual time lag between hand and paddle movements. A State Representation is a representation of delay using current state variables: the distance between the paddle and the ball originating from the delay may be considered as a spatial shift; the low sensitivity in the response of the paddle may be interpreted as a minifying gain; and the lag may be attributed to a mechanical resistance that influences paddle's movement. We found that the effects of prolonged exposure to the delayed feedback transferred to blind reaching and tracking tasks and caused participants to exhibit hypermetric movements. These results, together with simulations of our representation models, suggest that delay is not represented based on time, but rather as a spatial gain change in visuomotor mapping. Significance Statement3 It is known that the brain copes with sensory feedback delays to control movements, but it is unclear whether it does so using a representation of the actual time lag. We addressed this question by exposing participants to a visuomotor delay during a dynamic game of pong.Following the game, participants exhibited hypermetric reaching and tracking movements that indicate that delay is represented as a visuomotor gain rather than as a temporal shift.