Why is it so difficult to tell the difference between right and left?
Up and down is simple. The same goes for front and back. Why is right and left so much trickier?
Published
We know our right and left in theory – or if we think about it.
But making a snap decision or giving someone directions can make that knowledge go haywire.
For some people, it’s easiest just to guess. At 50 per cent, the chance of getting it right are pretty high.
Others use tricks. Either they quickly check which hand they are writing with, or they look down at their ring finger to find their wedding ring.
Why is this discernment so difficult for some people?
Constantly changing perspective
“Up and down is easy because we always maintain a position where our head is up and our legs are down,” says Helene Hjelmervik, a researcher in psychology at Kristiania University College. She published a study on the topic in 2015.
Our point of reference is always the same – the sky is always above us, and we always stand with our feet on the ground.
That isn’t the case when discriminating between right and left.
“The world we see to our right and left changes as we move,” Hjelmervik says.
The person in front of us might first be standing to our left, but by moving just one step to the side, she ends up to our right.
This is one of the reasons why right and left are harder to distinguish than up and down.
Watch on the left, wedding ring on the right
Another reason for the confusion, according to Hjelmervik, is that we are symmetrical organisms in the right-left dimension.
That is: we’re the same on our right and left sides.
“One of the first researchers to study right-left confusion said that ‘only an asymmetric organism will be able to discriminate right from left,’” she says.
That’s why we make strategies to remember what is right and left – we wear our watch on our left wrist and write with our right hand, for example. We create an asymmetry in the symmetry to make it easier for ourselves.
By contrast, we are not symmetrical in the front and back dimension, which makes it easier to discern if something is in front or in back, says Hjelmervik.
Demanding task for our brain
When we try to discriminate between right and left, a lot of things happen in our brain at the same time.
The process requires language – finding the right words ‘left’ and ‘right’. Memory also enters in – remembering which side is left and which is right. And the process places demands on our spatial understanding. We need to understand whether objects around us are on the left or right side.
All of this happens in an area of the brain called the angular gyrus, which is located in the parietal lobe of our brain.
Developed problems with fingers
In an older study from 1995, American researchers found – as did the Norwegian study - that this part of the brain was clearly involved when we try to distinguish between right and left.
They discovered that people who suffered injuries in this particular area of the brain had problems with four things in particular:
1. They lost the ability to name or distinguish between their fingers.
2. They lost the ability to write.
3. They had trouble doing very simple arithmetic tasks.
4. They had trouble discriminating between right and left.
The disease is called Gerstmann Syndrome and is a very rare neurological condition.
Women struggle more often than men
Previous research has shown that women are worse at discriminating between right and left.
Numerous researchers have tried to figure out why.
“One hypothesis is that women have more symmetrical brains and that in contrast to men, they use both halves of the brain when solving tasks,” Hjelmervik says.
She and her colleagues wondered if this could be the reason why women have more problems with right and left discrimination.
Women use other parts of the brain
Hjelmervik and colleagues tested this hypothesis on 16 women and 15 men. All the participants were shown pictures of pointing hands in various orientations, either rotated or not rotated, while lying in an fMRI machine that recorded their brain activity.
The participants were asked to state whether the image presented was a right hand or a left hand.
The researchers found no supporting evidence for the posited hypothesis.
“On the other hand, we found that women engage the frontal lobe more when identifying right and left,” Hjelmervik says.
Just why this is, scientists don’t yet know.
Translated by Ingrid Nuse
Read the Norwegian version of this article on forskning.no
