Why Is It So Hard to Thread a Needle?


Scientists are shedding light on why threading a needle can be such a challenge, even if you do have good eyesight and a steady hand.

Trace is here to debunk some common vision myths that we've grown up believing.

It's got to do with the message your hands send to your brain, says Dr Stephanie Goodhew of the Australian National University's Research School of Psychology.

It has been known for some time that there is something special about the space around your hands when it comes to vision, says Goodhew, who is lead author of a new study published in a recent issue of the Psychonomic Bulletin & Review.

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"Visual stimuli are processed differently when they occur near our hands," she says.

If you are trying to detect flashing targets on a computer screen, you will perform better if your hands are near the screen, says Goodhew.

But, not all tasks are performed better when your hands are closer to them.

Carrying out tasks that require detailed processing like reading is subtly less efficient when your hands are in the picture, says Goodhew.

"You are a bit slower to read information near your hands," she says.

Such findings have led to different theories to explain what is happening in what is called the 'near-hand space' — the visual field around your hands.

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The "attentional theory" suggests that in this field, the brain allocates greater cognitive resources to attention. But another theory argues this doesn't explain why tasks like reading aren't better performed when your hands are close by.

This competing theory argues that the visual system is ruled by two types of cells. P cells, which are good at processing small spatial details like reading, and M cells that are not so good at picking up details, or colour, but are very fast to respond.

The theory is that the near-hand space is dominated by M cells, which are good at picking up moving objects, a flashing target but not so good at reading.

Goodhew and colleagues set up an experiment to test both the attentional and M cell theories.

"We found evidence for the M cell theory," she says.

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