Uncertainty modulated exploration in the trade-off between sensing and acting

Abstract

Many sensorimotor activities have a time constraint for successful completion. In this case, any time devoted to sensory processing is at the expense of time available for motor execution. Earlier studies have explored how this competition between sensory processing and motor execution is resolved by using experimental designs that segregate the sensing and acting phase of the task. It was found that participants switch from the sensing to the acting stage such that the overall (sensorimotor) uncertainty in the outcome of the task is minimized. An unexplained observation in these studies is the substantial variability in switching times. We investigated the variability in switching time by correlating it with the underlying sensorimotor uncertainty. To this end, we used a modified version of the virtual ball catching paradigm proposed by Faisal & Wolpert (2009). Subjects were instructed to catch a ball, but as soon as they initiated their movement the ball disappeared. We extended the range of horizontal velocities and used two different start positions of the ball to quantify the dependence of sensory uncertainty on ball velocity. Velocity dependence of sensory uncertainty allowed us to manipulate sensory uncertainty and hence the sensorimotor uncertainty. We found that the variability in switching times is correlated with two factors. Firstly, variability in switching times is greater when variation in switching time has only minimal effects on sensorimotor uncertainty. Secondly, variability in switching times is greater when the sensorimotor uncertainty is larger. Our results suggest that the variability in switching time reflects an uncertainty-driven exploratory process.

Exploration of sensory-motor tradeoff behavior in Parkinson’s disease

“…For healthy controls the slopes were positive for both the predicted minimal sensorymotor uncertainty [t(9) = 4.75, p < 0.005] and the shallowness of the valley [t(9) = 5.51, p < 0.001]. This is in line with our earlier findings in young subjects (Sengupta et al, 2018). By contrast, in the PD group only the correlation between switching time and shallowness of the valley was positive [t(8) = 2.79, p < 0.05], while the correlation with minimal sensory-motor uncertainty was not significantly different from zero [t(8) = -0.38, p = 0.7].…”

“…Within the sensory-motor tradeoff framework (using equation 4), we can only compute the optimal switching time, i.e., the time point at which an ideal observer would start acting, but does not explain variability around the optimal switching time. In our earlier work (Sengupta et al, 2018) we found that the variability in switching time correlated with parameters derived from the optimal sensory-motor noise tradeoff framework (equations 1-4). We follow the same approach here and correlate the observed variability in switching time with the predicted minimal sensory-motor uncertainty σ combined (t optimal ) on each trial.…”

“…In our previous work (Sengupta et al, 2018) we found that the variability in switching time was not entirely arbitrary, but was correlated with the shallowness of the valley and the predicted minimal sensory-motor uncertainty. The shallowness of the valley is a measure of how the predicted sensory-motor uncertainty changes in response to variability in switching time: the shallower the valley, the smaller the effect of variations in switching time on catch performance.…”

“…In our earlier work (Sengupta et al, 2018) we found that the variability in switching time in the sensory-motor tradeoff task is modulated by the predicted minimal sensorymotor uncertainty and by the shallowness of the valley (that is the effect of variability in switching time on sensory-motor uncertainty). Both these factors are computed from the models of sensory and motor uncertainty.…”

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“…Há evidências de que a atenção relaciona-se à qualidade do processo decisório em contextos como detecção de predadores, competição, comunicação e aprendizado social (RANGE et al, 2009;BEAUCHAMP, 2010 O processo decisório tem sido amplamente investigado, posto que resulta de um sofisticado mecanismo neurobiológico de "acoplamento" entre a percepção sensorial e a ação motora. Este fenômeno, denominado transformação sensoriomotora é profundamente conhecido em animais vertebrados e invertebrados, e está intimamente relacionado à eficiência dos comportamentos de fuga e alimentação (CARD; DICKINSON, 2008;HOFMANN et al, 2013;BAR et al, 2015;TOMASSINI;MORRONE, 2016;SENGUPTA et al, 2018). Em animais vertebrados, a transformação sensoriomotora é um fenômeno reconhecidamente variável, dependente do contexto e experiência (HANES;SCHALL, 1996).…”