Abstract/Summary

Working memory, the ability to hold information in mind over the short term towards a behavioural goal, plays a fundamental role in many of the cognitive processes we experience as humans. Yet distractions and interruptions can interfere with this ability. Cognitive control plays a key role in maintaining information in working memory and resolving interference, but the neural underpinnings of this process are not fully understood. This thesis explores the neural mechanisms of cognitive control in resolving interference from irrelevant information in visual working memory. Chapter 2 explored how visual distractions impacted memory precision of naturalistic objects, demonstrating that working memory remains robust despite visually engaging distractors. Chapter 3 demonstrated that the dorsolateral prefrontal cortex (dlPFC), crucial for cognitive control, supports resilience against distractions. Suppressing dlPFC activity with transcranial magnetic stimulation (TMS) reduced memory recall precision, providing causal evidence of its role in mitigating distractor effects. To further investigate cognitive control, Chapters 2 and 3 examined the relationship between individual differences in mind-wandering, trait worry, and distractor mitigation. Whilst worry did not impair distraction mitigation—possibly due to compensatory mechanisms—in a surprising finding, individuals with less control over mind-wandering benefited from distractors, in which they may have helped to refocus attention away from internal thoughts. In addition, pupillometry revealed that fluctuations in cognitive control, reflected by pupil dilation, predicted memory performance, and reflected cognitive efforts exerted in the presence of visual distractors. Chapter 4 investigated how cognitive control protects memory contents from interruptions. Using multivariate pattern analysis (MVPA) of functional magnetic resonance imaging (fMRI) data, memory content was decoded within the Multiple Demand (MD) network during interruption tasks. Results showed that more challenging tasks enhanced memory representations within MD regions, reflecting the nature of cognitive control mechanisms in this context. These findings deepen our understanding of how the MD system supports flexible behaviour, and provide valuable insights for clinical interventions, i.e. neuromodulation, aiming to improve resistance to interference in working memory in conditions such as attention deficit hyperactivity disorder, schizophrenia, and dementia.