The influence of attention on dual-task performances and cortical excitability

In the literature researchers have endeavored to try and explain the phenomena of dualtask interference. Dual-task interference refers to the finding that when people perform two tasks simultaneously there is often a decrease in performance compared to when they perform one task alone (Pashler, 1994). Despite vast amounts of research exploring this, there has been no unified consensus about why dual-task interference actually occurs. This literature review first explains the methodology termed the dual-task paradigm that is common used in research to study these interference effects. Following this the cognitive explanations for dual-task interference effects, namely the resource model and bottleneck model are explored. A number of studies are then presented that employed both cognitive and motor tasks to examine these effects. Another less common explanation presented in the literature termed the cross-talk model is then reviewed. Cross-talk according to Navon and Miller (1987) is defined as when two tasks use separate mechanisms that interfere with each other, rather then share or compete for resources. This notion of cross-talk can be interpreted from a neural perspective, thus neural cross-talk can be seen as referring to when an area of the cortex activated during the performance of one task affects a different area of the cortex activated during the performance of a second task resulting in interference. This review then explores a number of studies that used electrophysiological techniques, such as transcranial magnetic stimulation and position emission tomography that present findings consistent with the notion of neural cross-talk. Building on this notion of neural cross-talk research is then presented that suggests that neural cross-talk may play an important role in behaviour. The final part of this review explores evidence to suggest that neural cross-talk is modifiable. Overall, the literature presented in this review highlights the fact that further research into the cause of dual-task interference is warranted. The evidence also suggests that neuralcross talk may play an important role in this interference; thus neural cross-talk should be explored in greater depth in future research examining interference