Why Does Dual-Tasking Hamper Implicit Sequence Learning?

Abstract

Research on the limitations of dual-tasking might profit from using setups with a predictable sequence of stimuli and responses and assessing the acquisition of this sequence. Detrimental effects of dual-tasking on implicit sequence learning in the serial reaction time task (SRTT; Nissen & Bullemer, 1987) - when paired with an uncorrelated task - have been attributed to participants' lack of separating the streams of events in either task. Assuming that co-occurring events are automatically integrated, we reasoned that participants could need to first learn which events co-occur, before they can acquire sequence knowledge. In the training phase, we paired an 8-element visual-manual SRTT with an auditory-vocal task. Afterwards, we tested under single-tasking conditions whether SRTT sequence knowledge had been acquired. By applying different variants of probabilistic SRTT-tone pairings across three experiments, we tested what type of predictive relationship was needed to preserve sequence learning. In Experiment 1, where half of the SRTT-elements were paired to 100% with one specific tone and the other half randomly, only the fixedly paired elements were learned. Yet, no sequence learning was found when each of the eight SRTT-elements was paired with tone identity in a 75%-25% ratio (Experiment 2). Sequence learning was, however, intact when the 75%-25% ratio was applied to the four SRTT target locations instead (Experiment 3). The results suggest that participants (when lacking a separation of the task representations while dual-tasking) can learn a sequence inherent in one of two tasks to the extent that across-task contingencies can be learned first.

Keywords: Implicit Sequence Learning; Multitasking; Prediction.

Figure 1

Mean RTs (left y-axis) and error rates (right y-axis) in the regular and the random single-task SRTT test blocks shown separately for SRTT-elements that had been fixedly vs. randomly paired with the tones during the training phase of Experiment 1. Error bars represent the 95% within-subjects confidence intervals of the learning effects (Loftus & Masson, 1994).

Figure 2

Mean RTs (left y-axis) and error rates (right y-axis) in the regular and the random single-task SRTT test blocks in Experiments 2 and 3. Error bars represent the 95% within-subjects confidence intervals of the learning effects in each experiment (Loftus & Masson, 1994).

Figure A1

Distribution of the inter-response intervals (IRIs) in the dual-task training phase of the 3 Experiments. In the first bin (i.e., <–100), the minimum IRI is –1655 ms (Experiment 1). In the last bin (i.e., >1000) the maximum IRI is 1811 ms (Experiment 3).