One thing at a time: the neuroscience of focused attention and debunking multi-tasking

Published by Dr Fiona Warner-Gale on 7 Jan 2021

For decades we have moved toward the premise that multi-tasking is a real skill and that if we can juggle several tasks at a time, we are really achieving a lot and powering through our work – but is this really true or a mere fallacy?

Essentially, we are dividing our attention between sometimes numerous tasks, switching from one thing to another, performing very quickly and shifting goals repeatedly. It sounds very promising in this high-pressure, high demand, instant world that we find ourselves in.

Businesswoman multi-tasking

But does it really get the job done, and how does it have an impact on the way we approach and execute the tasks we want to breeze through?

When we are multi-tasking, each task draws on our cognitive resources, they are in competition for our attention and this quickly drains our concentration and our ability to process effectively

(attention residue). It may feel like we are getting through that ever-increasing to-do list, but when our attention is constantly in demand, we may not be completing work particularly well.

Researchers have found that when people switch between tasks there can be an excessive demand on the executive function of the frontal lobe, and fMRI studies have implied that it can actually cause ‘bottlenecks’ to cognitive processing in several regions of the frontal lobe (Costandai, 2007). Studies have mainly examined the ability to perform sensory-motor tasks, responding to both verbal and visual stimulus- these studies have identified that several regions of the brain were activated at one time (Fougnie & Marois, 2009).

These studies also showed that when two tasks were performed in quick succession, there was a long delay in responding to the second task, and in addition the responses to the second tasks were also less accurate. The impact of this neural switching means that we have a period of cognitive latency – where the brain lags to switch between tasks, leading to a delayed response to one of those tasks. In addition, the discovery of cognitive ‘bottlenecks’ meant that there was a queuing of the information processing functions, so rather than doing two things at once, the brain processed the task one at a time- the implication of this is that we can only truly hold one task within our attention at any one time.  An everyday example of this could be; responding to your child, whilst looking for ingredients and removing your glasses – it’s more than likely you will find your glasses later in the fridge!

Happy businessmanAlso, there is evidence to suggest that the stress of multi-tasking can also stimulate the production of cortisol and adrenaline, and as we know from work that has focused on the prolonged release of these hormones on the brain, this can hinder our cognitive function and our ability to store and retrieve memories, vital to the decision-making process. Levitin (2015) suggests that this prolonged exposure to stress can result in ‘brain fog’ and scrambled thinking, a well-known complaint for people whose work places many and varied demands on them.

These effects on the brain and our decision-making process come at a price. Ultimately, the higher the cognitive load, the faster our energy reserves become depleted, the less effective we are in performing a task (Dimitriada & Psychogios, 2016). The more tasks you attempt to juggle simultaneously, the greater the impact on working memory. One specific cost here is ‘dual task interference’ – without the focused attention we require to encode our memory, the greater the impact is on our stored resources, needed for decision making and learning.

However, all is not lost, we can actually train ourselves to reduce the costs of multi-tasking. Through limiting the time we spend on multi-tasking activities and through developing the habit of focused attention (deep work), we can actually help to reduce mental strain, improve performance and enable our neurons to physically improve to produced faster, cleaner transition of messages, to help us make decisions faster and smarter.


Costandi, M. (2007). How the brain limits our ability to multitask (Accessed 15.05.2020)

Dimitriadis, N., & Psychogios, A. (2016). Neuroscience for Leaders: A brain adaptive leadership approach. London, Kogan Page.

Fougnie, D.L., & Marois, R. (2009). Dual-task interference in visual working memory: A limitation in storage capacity but not in encoding or retrieval. Attention, Perception & Psychophysics. 71: 1831-1841

Levitin, D (2015). Why the modern world is bad for our brain. Neuroscience, The Observer. (Accessed 15.05.20)

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