Original scientific paper

Dynamics of two psychomotor activities: Chaotic properties

Ana Proroković
Ljiljana Gregov

Abstract

The aim of this study was to find out whether observed time series of complex reaction time (CRT) and tapping intervals (TI) reflect nonlinear, chaotic dynamics of underlying cognitive and motor processes. Seven female subjects, aged between 19-25 participated in 2x2 within groups factor experiment (two levels of task difficulty and two types of performance; single and dual). Seven time series were observed: Four CRT series (single and dual performance of two primary tasks) and three TI time series (single performance and dual performance with two primary tasks. Analysis of CRT series and TI time series included calculation of various nonlinear parameters (correlation dimension, largest Lyapunov exponent), as well as an application of quantitative recurrence analysis (%determinism, divergence) and the surrogate data technique, for testing nonlinearity. The results indicated the existence of chaotic dynamics in human response time, as well as in tapping data. In general, it seems that increased task requirements (difficulty) caused a reduction in the dimensionality of CRT series, i.e. underlying system dynamics. It was also found that one of the nonlinear properties of the CRT series and TI time series was their sensitive dependence on initial conditions. Maximum Lyapunov exponents for CRT and TI time series were greater for more complex tasks, indicating deterministic and chaotic nature of undergoing cognitive and motor processes.

Keywords

nonlinear dynamics; psychomotor activity; dimensionality; predictability

Hrčak ID:

1985

URI

https://hrcak.srce.hr/1985

Publication date:

22.1.2005.

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