Ways to Improve Multitasking: Effects of Predictability after Single- and Dual-Task Training.

Harald Ewolds,Laura Broeker,Markus Raab,Rita F De Oliveira,Stefan Künzell

doi:10.5334/joc.142

Abstract

In this study we investigated the effect of predictability on dual-task performance in two experiments. In the first experiment 33 participants separately practiced a continuous tracking task and an auditory reaction time task. Both tasks had a repeating element that made them predictable; in the tracking task this was a repeating segment, and in the auditory task this was an auditory sequence. In addition, one group obtained explicit knowledge about the repeating sequence in the tracking task while the other group trained implicitly. After training, single- and dual-task performance was tested at a post test and retention test. Results showed that predictability only improved performance in the predictable tasks themselves and dual-task costs disappeared for the tracking task. To see whether the task-specific effect of predictability was the results of task prioritization, or because task representations did not have much chance to interact with each other, we conducted a second experiment. Using the same tasks as in Experiment 1, 39 participants now trained both tasks simultaneously. Results largely mirrored those of the first experiment, demonstrating that freed-up resources due to predictability in one task could not be re-invested to improve in the other task. We conclude that predictability has a positive but task-specific effect on dual-task performance.

Highlights

For the tracking task there was a main effect of Block, F(1.81, 56.04) = 9.63, p < .001, ηp2 = .237 (Block 1: M = 1.64 ± 0.24 cm; Block 4: M = 1.50 ± 0.32 cm), showing that participants improved tracking performance across blocks in general, and a main effect of Segment, F(1, 31) = 26.42, p < .001, ηp2 = .460 (Repeating segment: M = 1.51 ± 0.27 cm; Random segment: M = 1.60 ± 0.26 cm), showing that participants performed better on repeating compared to random segments
The goal of the first experiment was to investigate the effect of predictability on dual tasks after single-task training. Predictability benefitted both tasks under dual-task conditions but this did not extend to the other task, mirroring the results of previous studies that the effect of predictability seems to be contained within the predictable task itself (Ewolds et al, 2017)
Even though data suggested that resources were freed up in both tasks, participants did not exploit this to improve performance on the other task, as indicated by the absent effect of tones on RMSE

Summary

Introduction

Some studies have seen reduced or even eliminated dual-task costs, either after large amounts of training (Ruthruff et al, 2006), or by using ideomotor-compatible tasks (Halvorson et al, 2013; Halvorson & Hazeltine, 2015). Künzell et al (2018) argued that both large amounts of practice and ideomotor compatibility, make tasks more predictable which can facilitate automatic processing and reduce interference between tasks. To further elucidate the role of predictability in multitasking, Experiment 1 of our study aimed to elaborate on these previous findings. We investigated whether the simultaneous performance of two predictable tasks, as opposed to just one predictable task as in previous studies, would enhance dual-task performance in both tasks after single-task training on both tasks. Following the findings of Experiment 1, which indicated only task-specific effects of predictability, we decided to conduct

Objectives

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Conclusion