Tilo Strobach

Video game practice optimizes executive control skills in dual-task and task switching situations

We examined the relation of action video game practice and the optimization of executive control skills that are needed to coordinate two different tasks. As action video games are similar to real life situations and complex in nature, and include numerous concurrent actions, they may generate an ideal environment for practicing these skills (Green & Bavelier, 2008). For two types of experimental paradigms, dual-task and task switching respectively; we obtained performance advantages for experienced video gamers compared to non-gamers in situations in which two different tasks were processed simultaneously or sequentially. This advantage was absent in single-task situations. These findings indicate optimized executive control skills in video gamers. Similar findings in non-gamers after 15 h of action video game practice when compared to non-gamers with practice on a puzzle game clarified the causal relation between video game practice and the optimization of executive control skills.

On methodological standards in training and transfer experiments

The past two decades have seen a tremendous surge in scientific interest in the extent to which certain types of training—be it aerobic, athletic, musical, video game, or brain trainer—can result in general enhancements in cognitive function. While there are certainly active debates regarding the results in these domains, what is perhaps more pressing is the fact that key aspects of methodology remain unsettled. Here we discuss a few of these areas including expectation effects, test–retest effects, the size of the cognitive test battery, the selection of control groups, group assignment methods, difficulties in comparing results across studies, and in interpreting null results. Specifically, our goal is to highlight points of contention as well as areas where the most commonly utilized methods could be improved upon. Furthermore, because each of the sub-areas above (aerobic training through brain training) share strong similarities in goal, theoretical framework, and experimental approach, we seek to discuss these issues from a general perspective that considers each as members of the same broad “training” domain.

On the impacts of working memory training on executive functioning.

Recent studies have reported improvements in a variety of cognitive functions following sole working memory (WM) training. In spite of the emergence of several successful training paradigms, the scope of transfer effects has remained mixed. This is most likely due to the heterogeneity of cognitive functions that have been measured and tasks that have been applied. In the present study, we approached this issue systematically by investigating transfer effects from WM training to different aspects of executive functioning. Our training task was a demanding WM task that requires simultaneous performance of a visual and an auditory n-back task, while the transfer tasks tapped WM updating, coordination of the performance of multiple simultaneous tasks (i.e., dual-tasks) and sequential tasks (i.e., task switching), and the temporal distribution of attentional processing. Additionally, we examined whether WM training improves reasoning abilities; a hypothesis that has so far gained mixed support. Following training, participants showed improvements in the trained task as well as in the transfer WM updating task. As for the other executive functions, trained participants improved in a task switching situation and in attentional processing. There was no transfer to the dual-task situation or to reasoning skills. These results, therefore, confirm previous findings that WM can be trained, and additionally, they show that the training effects can generalize to various other tasks tapping on executive functions.

Task switching: effects of practice on switch and mixing costs

In the task-switching paradigm, mixing costs indicate the performance costs to mix two different tasks, while switch costs indicate the performance costs to switch between two sequentially presented tasks. Applying tasks with bivalent stimuli and responses, many studies demonstrated substantial mixing and switch costs and a reduction of these costs as a result of practice. The present study investigates whether extensive practice of a task-switching situation including tasks with univalent stimuli eliminates these costs. Participants practiced switching between a visual and an auditory task. These tasks were chosen because they had shown eliminated performance costs in a comparable dual-task practice study (Schumacher et al. Psychol Sci 12:101–108, 2001). Participants either performed the tasks with univalent responses (i.e., visual-manual and auditory-verbal stimulus–response mappings) or bivalent responses (i.e., visual-manual and auditory-manual stimulus–response mappings). Both valence conditions revealed substantial mixing and switch costs at the beginning of practice, yet, mixing costs were largely eliminated after eight practice sessions while switch costs were still existent.

Adaptation effects of highly familiar faces: Immediate and long lasting.

A central problem of face identification is forming stable representations from entities that vary—both in a rigid and nonrigid manner—over time, under different viewing conditions, and with altering appearances. Three experiments investigated the underlying mechanism that is more flexible than has often been supposed. The experiments used highly familiar faces that were first inspected as configurally manipulated versions. When participants had to select the veridical version (known from TV/media/movies) out of a series of gradually altered versions, their selections were biased toward the previously inspected manipulated versions. This adaptation effect (face identity aftereffect, Leopold, Rhodes, Müller, & Jeffery, 2005) was demonstrated even for a delay of 24h between inspection and test phase. Moreover, the inspection of a specific image version of a famous person not only changed the veridicality decision of the same image, but also transferred to other images of this person as well. Thus, this adaptation effect is apparently not based on simple pictorial grounds, but appears to have a rather structural basis. Importantly, as indicated by Experiment 3, the adaptation effect was not based on a simple averaging mechanism or an episodic memory effect, but on identity-specific information.

Adaptive working-memory training benefits reading, but not mathematics in middle childhood

Working memory (WM) capacity is highly correlated with general cognitive ability and has proven to be an excellent predictor for academic success. Given that WM can be improved by training, our aim was to test whether WM training benefited academic abilities in elementary-school children. We examined 28 participants (mean age = 8.3 years, SD = 0.4) in a pretest-training-posttest-follow-up design. Over 14 training sessions, children either performed adaptive WM training (training group, n = 14) or nonadaptive low-level training (active control group, n = 14) on the same tasks. Pretest, posttest, and follow-up at 3 months after posttest included a neurocognitive test battery (WM, task switching, inhibition) and standardized tests for math and reading abilities. Adaptive WM training resulted in larger training gains than nonadaptive low-level training. The benefits induced by the adaptive training transferred to an untrained WM task and a standardized test for reading ability, but not to task switching, inhibition, or performance on a standardized math test. Transfer to the untrained WM task was maintained over 3 months. The analysis of individual differences revealed compensatory effects with larger gains in children with lower WM and reading scores at pretest. These training and transfer effects are discussed against the background of cognitive processing resulting from WM span training and the nature of the intervention.

Improved intertask coordination after extensive dual-task practice

This study examines whether an improved intertask coordination skill is acquired during extensive dual-task training and whether it can be transferred to a new dual-task situation. Participants practised a visual–manual task and an auditory–vocal task. These tasks were trained in two groups matched in dual-task performance measures before practice: a single-task practice group and a hybrid practice group (including single-task and dual-task practice). After practice, the single-task practice group was transferred to the same dual-task situation as that for the hybrid practice group (Experiment 1), both groups were transferred to a dual-task situation with a new visual task (Experiment 2), and both groups were transferred to a dual-task situation with a new auditory task matched in task difficulty (Experiment 3). The results show a dual-task performance advantage in the hybrid practice group over the single-task practice group in the practised dual-task situation (Experiment 1), the manipulated visual-task situation (Experiment 2), and the manipulated auditory-task situation (Experiment 3). In all experiments, the dual-task performance advantage was consistently found for the auditory task only. These findings suggest that extended dual-task practice improves the skill to coordinate two tasks, which may be defined as an accelerated switching operation between both tasks. This skill is relatively robust against changes of the component visual and auditory tasks. We discuss how the finding of task coordination could be integrated in present models of dual-task research.

Investigation on the improvement and transfer of dual-task coordination skills

Recent research has demonstrated that dual-task performance in situations with two simultaneously presented tasks can be substantially improved with extensive practice. This improvement was related to the acquisition of task coordination skills. Earlier studies provided evidence that these skills result from hybrid practice, including dual and single tasks, but not from single-task practice. It is an open question, however, whether task coordination skills are independent from the specific practice situation and are transferable to new situations or whether they are non-transferable and task-specific. The present study, therefore, tested skill transfer in (1) a dual-task situation with identical tasks in practice and transfer, (2) a dual-task situation with two tasks changed from practice to transfer, and (3) a task switching situation with two sequentially presented tasks. Our findings are largely consistent with the assumption that task coordination skills are non-transferable and task-specific. We cannot, however, definitively reject the assumption of transferable skills when measuring error rates in the dual-task situation with two changed tasks after practice. In the task switching situation, single-task and hybrid practice both led to a transfer effect on mixing costs.

Practice-related optimization and transfer of executive functions: a general review and a specific realization of their mechanisms in dual tasks

Improvements in performing demanding and complex task situations are typically related to the optimization of executive functions and efficient behavioral control. The present study systematizes and reviews the optimization of different executive function types: Shifting, Inhibition, Updating, and Dual tasking. In particular, we focus on optimisations of these functions with training and on transfer effects of related training skills to non-trained situations. The aim of the study’s empirical part (see also Appendix) was to investigate the specific mechanisms of executive functions in the context of Dual tasking, leading to improved dual-task performance after practice. More specifically, we tested the Efficient Task Instantiation (ETI) model that includes specific assumptions regarding practice-related improvements of executive task coordination skills: Dual-task performance is improved with practice because of an efficient and conjoint instantiation of sets of relevant task information in working memory at the onset of a dual task. According to our knowledge, the ETI model is one of the first that allows illustrating the contribution of cognitive mechanisms underlying practice-related improvements in performing dual tasks and the impact of task coordination skills on this performance.

Effects of extensive dual-task practice on processing stages in simultaneous choice tasks

Schumacher et al. Psychological Science 12:101–108, (2001) demonstrated the elimination of most dual-task costs (“perfect time-sharing”) after extensive dual-task practice of a visual and an auditory task in combination. For the present research, we used a transfer methodology to examine this practice effect in more detail, asking what task-processing stages were sped up by this dual-task practice. Such research will be essential to specify mechanisms associated with the practice-related elimination of dual-task costs. In three experiments, we introduced postpractice transfer probes focusing on the perception, central response-selection, and final motor-response stages. The results indicated that the major change achieved by dual-task practice was a speed-up in the central response-selection stages of both tasks. Additionally, perceptual-stage shortening of the auditory task was found to contribute to the improvements in time-sharing. For a better understanding of such time-sharing, we discuss the contributions of the present findings in relation to models of practiced dual-task performance.