Think you're good at multi-tasking? Here's how your brain compensates – and how this changes with age

• We answer work emails while watching TV, make shopping lists in meetings and listen to podcasts when doing the dishes.
• We attempt to split our attention countless times a day when juggling both mundane and important tasks.

Doing more things, but less effectively

• In particular, the brain’s planning centres in the frontal cortex (and connections to parieto-cerebellar system, among others) are needed for both motor and cognitive tasks.
• The more tasks rely on the same sensory system, like vision, the greater the interference.

This is why multi-tasking, such as talking on the phone, while driving can be risky. It takes longer to react to critical events, such as a car braking suddenly, and you have a higher risk of missing critical signals, such as a red light. The more involved the phone conversation, the higher the accident risk, even when talking “hands-free”.
Generally, the more skilled you are on a primary motor task, the better able you are to juggle another task at the same time. Skilled surgeons, for example, can multitask more effectively than residents, which is reassuring in a busy operating suite. Highly automated skills and efficient brain processes mean greater flexibility when multi-tasking.

Adults are better at multi-tasking than kids

• Both brain capacity and experience endow adults with a greater capacity for multi-tasking compared with children.
• The ability to walk and think at the same time gets better over childhood and adolescence, as do other types of multi-tasking.
• Alternately, outside the lab, the cognitive task might fall by wayside as the motor goal takes precedence.
• This means better capacity to maintain performance at or near single-task levels.

What about as we approach older age?

Older adults are more prone to multi-tasking errors. When walking, for example, adding another task generally means older adults walk much slower and with less fluid movement than younger adults. These age differences are even more pronounced when obstacles must be avoided or the path is winding or uneven.
Older adults tend to enlist more of their prefrontal cortex when walking and, especially, when multi-tasking. This creates more interference when the same brain networks are also enlisted to perform a cognitive task. These age differences in performance of multi-tasking might be more “compensatory” than anything else, allowing older adults more time and safety when negotiating events around them.

Older people can practise and improve

• Testing multi-tasking capabilities can tell clinicians about an older patient’s risk of future falls better than an assessment of walking alone, even for healthy people living in the community.
• Patients can then practise and improve these abilities by, for example, pedalling an exercise bike or walking on a treadmill while composing a poem, making a shopping list, or playing a word game.

There are times when we do think better when moving

Let’s not forget that a good walk can help unclutter our mind and promote creative thought. And, some research shows walking can improve our ability to search and respond to visual events in the environment.

But often, it’s better to focus on one thing at a time

• In many areas of life – home, work and school – we think it will save us time and energy.
• Multi-tasking can sometimes sap our reserves and create stress, raising our cortisol levels, especially when we’re time-pressured.
• Sometimes, it’s better to focus on one thing at a time.

Peter Wilson has received prior funding from the Australian Research Council (ARC), studying the motor and cognitive development of children. He currently receives funding from the Australian Automobile Association (AAA), studying hazard perception in older adult pedestrians.