We’re all time-poor, so multi-tasking is seen as a necessity of modern living. 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.

But doing two things at the same time isn’t always as productive or safe as focusing on one thing at a time.

The dilemma with multi-tasking is that when tasks become complex or energy-demanding, like driving a car while talking on the phone, our performance often drops on one or both.

Here’s why – and how our ability to multi-task changes as we age.

Doing more things, but less effectively

The issue with multi-tasking at a brain level, is that two tasks performed at the same time often compete for common neural pathways – like two intersecting streams of traffic on a road.

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.

You may have noticed that when you start thinking about a problem, you walk more slowly, and sometimes to a standstill if deep in thought. The ability to walk and think at the same time gets better over childhood and adolescence, as do other types of multi-tasking.

When children do these two things at once, their walking speed and smoothness both wane, particularly when also doing a memory task (like recalling a sequence of numbers), verbal fluency task (like naming animals) or a fine-motor task (like buttoning up a shirt). Alternately, outside the lab, the cognitive task might fall by wayside as the motor goal takes precedence.

Brain maturation has a lot to do with these age differences. A larger prefrontal cortex helps share cognitive resources between tasks, thereby reducing the costs. This means better capacity to maintain performance at or near single-task levels.

The white matter tract that connects our two hemispheres (the corpus callosum) also takes a long time to fully mature, placing limits on how well children can walk around and do manual tasks (like texting on a phone) together.

For a child or adult with motor skill difficulties, or developmental coordination disorder, multi-tastking errors are more common. Simply standing still while solving a visual task (like judging which of two lines is longer) is hard. When walking, it takes much longer to complete a path if it also involves cognitive effort along the way. So you can imagine how difficult walking to school could be.

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.

Testing can be as simple as asking someone to walk a path while either mentally subtracting by sevens, carrying a cup and saucer, or balancing a ball on a tray.

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.

The goal is for patients to be able to divide their attention more efficiently across two tasks and to ignore distractions, improving speed and balance.

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

We often overlook the emotional and energy costs of multi-tasking when time-pressured. In many areas of life – home, work and school – we think it will save us time and energy. But the reality can be different.

Multi-tasking can sometimes sap our reserves and create stress, raising our cortisol levels, especially when we’re time-pressured. If such performance is sustained over long periods, it can leave you feeling fatigued or just plain empty.

Deep thinking is energy demanding by itself and so caution is sometimes warranted when acting at the same time – such as being immersed in deep thought while crossing a busy road, descending steep stairs, using power tools, or climbing a ladder.

So, pick a good time to ask someone a vexed question – perhaps not while they’re cutting vegetables with a sharp knife. Sometimes, it’s better to focus on one thing at a time.

Peter Wilson, Professor of Developmental Psychology, Australian Catholic University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

If you head to the shops to buy bread, you’ll face a variety of different options.

But it can be hard to work out the difference between all the types on sale.

For instance, you might have a vague idea that wholemeal or wholegrain bread is healthy. But what’s the difference?

Here’s what we know and what this means for shoppers in Australia and New Zealand.

Let’s start with wholemeal bread

According to Australian and New Zealand food standards, wholemeal bread is made from flour containing all parts of the original grain (endosperm, germ and bran) in their original proportions.

Because it contains all parts of the grain, wholemeal bread is typically darker in colour and slightly more brown than white bread, which is made using only the endosperm.

How about wholegrain bread?

Australian and New Zealand food standards define wholegrain bread as something that contains either the intact grain (for instance, visible grains) or is made from processed grains (flour) where all the parts of the grain are present in their original proportions.

That last part may sound familiar. That’s because wholegrain is an umbrella term that encompasses both bread made with intact grains and bread made with wholemeal flour. In other words, wholemeal bread is a type of wholegrain bread, just like an apple is a type of fruit.

Don’t be confused by labels such as “with added grains”, “grainy” or “multigrain”. Australian and New Zealand food standards don’t define these so manufacturers can legally add a small amount of intact grains to white bread to make the product appear healthier. This doesn’t necessarily make these products wholegrain breads.

So unless a product is specifically called wholegrain bread, wholemeal bread or indicates it “contains whole grain”, it is likely to be made from more refined ingredients.

Which one’s healthier?

So when thinking about which bread to choose, both wholemeal and wholegrain breads are rich in beneficial compounds including nutrients and fibre, more so than breads made from further-refined flour, such as white bread.

The presence of these compounds is what makes eating wholegrains (including wholemeal bread) beneficial for our overall health. Research has also shown eating wholegrains helps reduce the risk of common chronic diseases, such as heart disease.

The table below gives us a closer look at the nutritional composition of these breads, and shows some slight differences.

Wholegrain bread is slightly higher in fibre, protein, niacin (vitamin B3), iron, zinc, phosphorus and magnesium than wholemeal bread. But wholegrain bread is lower in carbohydrates, thiamin (vitamin B1) and folate (vitamin B9).

However the differences are relatively small when considering how these contribute to your overall dietary intake.

Which one should I buy?

Next time you’re shopping, look for a wholegrain bread (one made from wholemeal flour that has intact grains and seeds throughout) as your number one choice for fibre and protein, and to support overall health.

If you can’t find wholegrain bread, wholemeal bread comes in a very close second.

Wholegrain and wholemeal bread tend to cost the same, but both tend to be more expensive than white bread.

Margaret Murray, Senior Lecturer, Nutrition, Swinburne University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.