Time-based task expectancy: perceptual task indicator expectancy or expectancy of post-perceptual task components?

Abstract

The temporal predictability of upcoming events plays a crucial role in the adjustment of anticipatory cognitive control in multitasking. Previous research has demonstrated that task switching performance improved if tasks were validly predictable by a pre-target interval. Hence, far, the underlying cognitive processes of time-based task expectancy in task switching have not been clearly defined. The present study investigated whether the effect of time-based expectancy is due to expectancy of post-perceptual task components or rather due to facilitation of perceptual visual processing of the coloured task indicator. Participants performed two numeric judgment tasks (parity vs. magnitude), which were each indicated by two different colours. Each task was either more or less frequently preceded by one of two intervals (500 ms or 1500 ms). Tasks were indicated either by colours that were each more frequently (or in Exp. 1 also less frequently) paired with the interval or by colours that were equally frequent for each interval. Participants only responded faster when colour and task were predictable by time (expected colour), not when the task alone was predictable (neutral colour). Hence, our results speak in favour of perceptual time-based task indicator expectancy being the underlying cognitive mechanism of time-based expectancy in the task switching paradigm.

Keywords: Foreperiod; Task switching; Temporal preparation; Time-based expectancy.

Fig. 1

Example of the trial procedure in Experiment1 with different combinations of foreperiod, colour and task, resulting in 90% colour predictability and 70% task predictability. In a and c the specific task and its indicating colour are both either expected or unexpected. In b and d the other two task-indicating colours are neutral (50% of occurrence after both FPs). But the tasks are either still expected or unexpected

Fig. 2

Results of analysis in Experiment 1. a Mean RTs for each condition (dots; 1 = expected colour and task, 2 = unexpected colour and task, 3 = neutral colour and expected task, 4 = neutral colour and unexpected task) and corresponding pairwise differences (bars). b Mean ERs for each condition (dots) and corresponding pairwise differences (bars). Numbers beside the dots and the bars indicate the numerical values of means. Error bars represent ± 1 SEM, numbers above error bars are the numerical values of the SEMs. * p < .05. The results are averaged across FPs and task transition

Fig. 3

Results of Experiment 2. a Mean RTs for each condition (dots; 1 = expected colour and task, 3 = neutral colour and expected task, 4 = neutral colour and unexpected task) and corresponding pairwise differences (bars). b Mean ERs for each condition (dots) and corresponding pairwise differences (bars). Numbers beside the dots and the bars indicates the numerical values of means. Error bars represents ± 1 SEM, numbers above error bars are the numerical values of the SEMs. *p < .05. The results are averaged across FPs and task transition

Fig. 4

Results of exploratory analysis in Experiment 1. a Mean RTs for each condition (dots; 1 = expected colour and task, 4 = neutral colour and unexpected task) and corresponding pairwise differences (bars). b Mean ERs for conditions 1 and 4 (dots) and corresponding pairwise differences (bars). Numbers beside the dots and the bars indicate the numerical values of means. Error bars represent ± 1 SEM, numbers above error bars are the numerical values of the SEMs. *p < .05. The results are averaged across FPs and task transition