Temporal Structure in Sensorimotor Variability: A Stable Trait, But What For?

Abstract

Human performance shows substantial endogenous variability over time, and this variability is a robust marker of individual differences. Of growing interest to psychologists is the realisation that variability is not fully random, but often exhibits temporal dependencies. However, their measurement and interpretation come with several controversies. Furthermore, their potential benefit for studying individual differences in healthy and clinical populations remains unclear. Here, we gather new and archival datasets featuring 11 sensorimotor and cognitive tasks across 526 participants, to examine individual differences in temporal structures. We first investigate intra-individual repeatability of the most common measures of temporal structures — to test their potential for capturing stable individual differences. Secondly, we examine inter-individual differences in these measures using: (1) task performance assessed from the same data, (2) meta-cognitive ratings of on-taskness from thought probes occasionally presented throughout the task, and (3) self-assessed attention-deficit related traits. Across all datasets, autocorrelation at lag 1 and Power Spectra Density slope showed high intra-individual repeatability across sessions and correlated with task performance. The Detrended Fluctuation Analysis slope showed the same pattern, but less reliably. The long-term component (d) of the ARFIMA(1,d,1) model showed poor repeatability and no correlation to performance. Overall, these measures failed to show external validity when correlated with either mean subjective attentional state or self-assessed traits between participants. Thus, some measures of serial dependencies may be stable individual traits, but their usefulness in capturing individual differences in other constructs typically associated with variability in performance seems limited. We conclude with comprehensive recommendations for researchers.

Variance (un)explained: Experimental conditions and temporal dependencies explain similarly small proportions of reaction time variability in linear models of perceptual and cognitive tasks

“…However, temporal dependencies are also present in tasks in which the same sensorimotor action is performed repeatedly and without any changes in experimental condition, such as tapping to a fixed interval (e.g., Chen et al, 2002;Lemoine et al, 2006;Madison, 2001;Perquin et al, 2023). Because the external environment remains the same, such dependencies must be driven endogenouslyi.e., arising from fluctuations in the internal system.…”

“…Trial with missing values were excluded from all analyses conducted in the current study. This seems to be the most common approach in studies on temporal dependencies, but it is important to note that the measurement of temporal dependencies is affected by trial exclusion (Karalunas et al, 2012;2014;Kofler et al, 2013;Perquin et al, 2023). Methods that deal with missing data, like data imputation, assume that data is missing at random (Donders et al, 2006).…”

“…Another line of research emphasises that the trial-by-trial variability of behaviour is not random, but exhibits structured dependencies over time (e.g., Gilden, 2001; Van Orden et al, 2003; Perquin et al, 2023; Torre et al, 2019; Torre & Wagenmakers, 2009; Wagenmakers et al, 2004; Welford, 1968). For example, most RT series show positive autocorrelations (Figure 1E), indicating that fast RTs are more likely followed by fast than slow RTs, and vice versa.…”

“…An example is the ‘sequential congruency’ (alternatively, ‘Gratton’) effect, which denotes the phenomenon that participants respond faster if the previous trial was of the same condition as the current one (e.g., both congruent in the Flanker task; Figure 1F). However, temporal dependencies are also present in tasks in which the same sensorimotor action is performed repeatedly and without any changes in experimental condition, such as tapping to a fixed interval (e.g., Chen et al, 2002; Lemoine et al, 2006; Madison, 2001; Perquin et al, 2023). Because the external environment remains the same, such dependencies must be driven endogenously – i.e., arising from fluctuations in the internal system.…”

“…Temporal dependencies have been found across many different tasks including cognitive control tasks, visual search, lexical decision, word naming, shape and colour discrimination, free choice RT, and racial implicit bias tasks (e.g., Annand & Holden, 2023; Correll, 2008; Gilden, 2001; Holden & Rajaraman, 2012; Marduski & LeBel, 2015; Van Order et al, 2003; Perquin et al, 2023; Simola et al, 2017). Importantly, they seem particularly present in tasks in which the same sensorimotor action is performed repeatedly without any changes in experimental condition, such as tapping to a fixed interval (e.g., Chen et al, 2002; Lemoine et al, 2006; Madison, 2001; Perquin et al, 2023). Because the external environment in such tasks remains unchanged, these dependencies must be driven endogenously – i.e., arising from fluctuations in the internal system.…”