Complexity of human response delay in intermittent control: The case of virtual stick balancing

TL;DR

This paper investigates the complex, variable nature of human response delays in balance control, showing they are distributed, adaptive, and correlated, challenging traditional fixed-delay models and suggesting new mathematical approaches.

Contribution

It provides experimental evidence that human response delay is a complex, adaptive, and long-range correlated variable, advocating for new formal models beyond fixed-delay approximations.

Findings

Response delay is a widely distributed random variable.

Response delay exhibits oscillatory and adaptive dynamics.

Response delay shows long-range correlations.

Abstract

Response delay is an inherent and essential part of human actions. In the context of human balance control, the response delay is traditionally modeled using the formalism of delay-differential equations, which adopts the approximation of fixed delay. However, experimental studies revealing substantial variability, adaptive anticipation, and non-stationary dynamics of response delay provide evidence against this approximation. In this paper, we call for development of principally new mathematical formalism describing human response delay. To support this, we present the experimental data from a simple virtual stick balancing task. Our results demonstrate that human response delay is a widely distributed random variable with complex properties, which can exhibit oscillatory and adaptive dynamics characterized by long-range correlations. Given this, we argue that the fixed-delay approximation ignores essential properties of human response, and conclude with possible directions for future developments of new mathematical notions describing human control.