Effects of physical effort on temporal processing

Abstract

The interaction between temporal processing and physical effort plays a crucial role in our daily activities. The present study therefore assesses the effects of a simple(est) physical effort (i.e., isometric handgrip) on temporal processing with concurrent time reproduction/production and handgrip tasks. Isometric handgrip can induce physical arousal, thereby accelerating time and leading to overestimation when sensory timing is under physical effort, but underestimation when the motor timing is under physical effort (i.e., arousal hypothesis). Alternatively, handgrip may directly impair temporal processing given the potential competition for attention, resulting in underestimated durations when sensory timing is under physical effort and overestimated durations when motor timing is under physical effort (i.e., competition hypothesis). Our data collected in 2023-2024 revealed that high physical effort increased estimated durations in the time reproduction task with concurrent sensory timing and handgrip (Experiments 1-2) but decreased estimated durations in the time production task with concurrent motor timing and handgrip (Experiment 4), supporting the arousal hypothesis. Two additional experiments ruled out some alternative accounts (e.g., response bias). In Experiment 3, the handgrip effect was absent when time was cued, instead of being experienced, under handgrip. In Experiment 5, the handgrip effects of sensory timing and motor timing canceled each other out (i.e., the El Greco effect) when both sensory timing and motor timing were under handgrip. Overall, these findings suggest that physical effort distorts perceived time, with increased arousal likely contributing to the acceleration of temporal processing. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Figure 1. The Competing Hypotheses.

Note. Illustration of the Arousal hypothesis (A) and Competition hypothesis (B). Blue background indicates the concurrent physical effort exertion. According to the scalar expectancy theory, temporal processing is based on a pacemaker-accumulator model, which consists of three components. Pacemaker, metaphorically represented by a metronome in the picture, steadily produces units of time indicated by the particles in the picture. Switch is open or close to let units of time out or in. Accumulator, like a container, collects and counts units of time. A: According to the arousal account, physiological arousal induced by high physical effort speeds up the rate of producing units of time in pacemaker (indicated by shorter distance between red particles than blue particles). B: According to the competition account, the two concurrently performed tasks compete for the shared attention resource, leading to more leaked units of time (red particles) through the opened switch under high physical effort than those (blue particles) under the low physical effort. This figure includes metronome graphic © Canva.com, used under Canva’s Pro Content License.

Figure 2. Concurrent Handgrip and Temporal Processing Dual-Task Paradigm.

Note. The general task procedure for Experiment 1-5 (A-E). Across all experiments, each trial started with a “Get Ready” signal, followed by a gauge displaying the required and exerted grip with a black line and the red bar, respectively, in real time. Participants then maintained the grip, without the immediate feedback, over the various temporal processing stages (only sensory timing in A and B, only motoring timing in D, both stages in E) of time reproduction (A, B, and E) or production (C and D) tasks across experiments. Feedback on handgrip task performance was provided at the end of the trial. A. In Experiment 1, grip was maintained through the standard duration (i.e., sensory timing stage). After the handgrip was released, the interval between two button presses was the estimated duration (i.e., motor timing stage). B. Experiment 2 was the same as Experiment 1, except for the fixed total duration of hand grip at 8 seconds. C. In Experiment 3 with the time production task, the sensory timing stage in Experiment 1 and 2 was replaced by a numerical cue indicating the time to be produced later. D. Experiment 4 was the same as Experiment 3, except for extended handgrip to the motor timing stage. E. In Experiment 5 with time reproduction task, both sensory timing and motor timing stages were under physical effort.

Figure 3. The Effects of Concurrent Handgrip on Temporal Processing Across the Experiments.

Note. The effects of concurrent handgrip on temporal processing across Experiment 1-5 (A-E). The RATIO on the y-axis represents the estimated duration divided by the standard duration presented for that trial. The error bars represent the standard error of the mean. Exp. = experiment; Phy. = physical.