Over the last decades, research investigating the effects of mindfulness-based interventions (MBIs) has grown exponentially1,2,3,4,5,6,7. More recently, attention has been directed towards understanding the neuro-cognitive processes that contribute to the therapeutic effects of MBIs and the meditation practices included in these MBIs. Emerging evidence suggests that meditation training or the participation in MBIs can result in improvements of cognitive processes such as attentional functions8,9, working memory10, and executive and meta-cognitive functions11. Such improvements in cognition are thought to interact with concurrent refinements of emotion regulation skills, resulting in enhanced psychological functioning and wellbeing12,13,14.

Although numerous researchers are dedicated to unravelling the functional and structural changes associated with mindfulness training, the understanding of the underlying psychological and neural mechanisms is currently limited15,16. To address this, several limitations have to be overcome, in particular the reliance on cross-sectional rather than longitudinal designs and the lack of active control conditions. Furthermore, the use of complex MBIs that include various components other than meditation hampers the ability to isolate specific effects that can be attributed directly to mindfulness meditation practice. For instance, prominent MBIs such as Mindfulness-based Stress Reduction (MBSR)17, Mindfulness-based Cognitive Therapy (MBCT)18 or Mindfulness-based Relapse Prevention (MBRP)19 include a whole range of components other than meditation such as psycho-education, yoga exercises, stretching and group discussions, while also integrating several different meditation exercises. As a result, it is impossible to gain certainty if, and to what extent, observed effects of these MBIs can be attributed to meditation in general, or to a specific meditation exercise in particular15,20,21. A large-scale MBCT dismantling trial found that an intervention identical to MBCT but excluding all meditation exercises, was therapeutically as effective as was standard MBCT with meditation practice22. As the field matures and such results are coming forward it is increasingly recognized, that it is essential to focus the research on the effects of specific meditation exercises and to describe these exercises clearly rather than getting trapped in the ambiguities of relying exclusively on “mindfulness” as umbrella term16,23.

Despite concerns regarding specific definitions of mindfulness, there is general agreement that mindfulness meditation as considered within psychological contexts entails paying attention to experiences that arise in the present moment combined with maintaining a non-judging, open, and accepting attitude13,17,24 while the role of attentional stability and associated meta-cognition as a foundational feature is highlighted9,15,25. In line with this, several studies confirmed that engaging in mindfulness meditation results in more efficient use of attentional control functions across a range of cognitive tasks9,26,27.

It is intriguing that a mental exercise that “merely” entails the voluntary focus on a simple object, such as the sensation of one’s own breath, combined with a non-reactive and accepting awareness of concurrently arising mental phenomena, can have far-reaching effects on cognitive functions. Such improvements have been explained in terms of brain network training, which is thought to enhance the functioning of interacting brain networks of attention21,25,28. For instance, each sequence of detecting that the mind got entangled in distractions such as mind wandering would engage the salience, executive control and orienting networks25,28 and over time lead to efficiency gains of these networks.

Such efficiency gains have been observed in different cognitive tasks that probe the functioning of these networks. For example, 16 weeks of regular, brief mindful breath awareness meditation enhanced the N2 event-related potential (ERP) during a computerised Stroop task, indicating improved attention allocation to the colour word stimuli. This improvement was associated with a reduction in the P3 ERP, signifying more efficient – or less resource-intensive – processing of incongruent stimuli that elicited a response conflict29. Similarly, several studies using the attentional blink task demonstrated more efficient allocation of attentional resources over time as a result of engaging with meditation practice30,31,32. Other studies have shown improved attentional functions and reduced engagement with distracting stimuli during meditation33,34,35, providing a plausible indication that attentional engagement during meditation transfers to generalised improvements of attentional functions.

Furthermore, engaging in meditation involves working memory functions, for example, while keeping the meditation object or the specific meditation instructions actively in mind. In line with this, research has demonstrated improvements in working memory, the capacity to retain and manipulate goal-relevant information, as a result of meditation practice10,36. The ability to sustain the meditation object in working memory and to return to it by rapidly recognising distraction and disengaging from it are thus key cognitive processes involved in mindfulness meditation practice.

Interestingly, evidence from cognitive neuroscience demonstrates the close interplay between attention and working memory, highlighting the important role of selective attention in encoding information in working memory37,38. In addition, the efficiency of allocating attentional resources to goal-relevant rather than irrelevant, distracting information predicts working memory performance39. Fukuda and Vogel40 demonstrate that the ability to rapidly disengage from distracting information is an important contributor to high-capacity working memory performance.

Multiple object tracking (MOT) paradigms, which combine sustained attention and visual working memory demands, have been employed successfully to investigate cognitive performance under challenging conditions41,42. Such research demonstrated that video gaming can lead to improved MOT performance43 and that, compared to matched controls, radar operators demonstrate superior performance on that task44. Furthermore, MOT appears to be a useful tool for tracking the development of visual attention skills in children45,46, for revealing age-related attentional decline47,48, and for investigation reductions of brain functional connectivity during high cognitive demand49. Störmer, Winther, Li, and Andersen50 combined MOT with electrophysiological recording of steady-state visual evoked potentials (SSVEP) elicited by flickering moving objects and confirmed that the continuous selective attentional enhancement of the tracked objects is directly associated with performance.

The SSVEP is the oscillatory response of cortical networks to flickering stimuli with the same fundamental frequency51. Its amplitude is an indicator for the allocation of selective attention and reflects the amount of neural resources devoted to the perception of an exogenous stimulus, but also to subsequent endogenous steps of processing52. The SSVEP initially originates in the primary visual cortices and then spreads along the neural pathways to higher areas, which are associated with relevant cognitive operations53,54.

Although the SSVEP is a particularly powerful tool for tracking the continuous allocation of attention over time, it has not yet been used for investigating attentional processes related to meditation. Similarly, the MOT has only rarely been used to study meditation. Despite its sensitivity to expertise and to some forms of training, and although it engages selective attention and working memory, to our knowledge only one study used a MOT paradigm to investigate attention and working memory in relation to meditation and mindfulness. Hartkamp and Thornton55 reported no improvements in tracking performance after a 6-day meditation retreat. However, methodological limitations (such as non-matched control group) and lacking information regarding participants’ initial meditation expertise makes it difficult to appraise these results.

In the current study, we aimed to combine the advantages of MOT and SSVEP to investigate whether eight weeks of mindful breath awareness meditation leads to improved neural network efficiency of sustained visual attention during encoding and maintenance of information in visual short-term memory. To achieve this, we employed a MOT task while concurrently recording SSVEPs. Importantly, we included an active control group, in which participants underwent training in progressive muscle relaxation (PMR)56, an approach that is sufficiently similar to mindfulness meditation while at the same time not including directions regarding the two key features of mindfulness meditation, namely the development of attentional stability and the emphasis on a non-judging, accepting attitude towards all experience. To allow a straightforward interpretation of meditation effects, participants in the meditation group engaged in only one exercise, mindful breath awareness meditation (MED), rather than a typical multi-component MBI programme.

The MOT task required participants to track simultaneously between two and five independently moving targets embedded in a total of 15 moving objects that are identical to the target. With increasing number of targets task difficulty increases significantly, avoiding potential ceiling effects that may have contributed to some ambiguous findings in this field25. The SSVEP was elicited by the continuous flickering of all moving objects and was used as an index of engagement and efficiency of attention networks.