Where’s the Middle of the Line?

weirdly accurate.

Where’s the Middle of the Line?

Can you find the exact middle of a line?

This line bisection test lets you find out how close you come to the exact middle of a line, and whether your eyes lean one way. Line bisection is the classic task behind research on pseudoneglect, a small and steady bias that healthy people show when they judge the middle of something. You cut eight ribbons, and only then does the page show your lean next to 50 young adults from a 2015 study by Learmonth and colleagues.

This test is line bisection staged as an opening-day ribbon cutting. Slide the scissors along each of eight ribbons until the dashed cut line sits on the middle, then snip; the halves fall and a tape measure shows the true middle next to your cut. The ribbons come in four lengths, each once left and once right of the screen’s centre, and in four steps that hang further and further off the middle of the symmetrical shopfront, so neither the screen nor the shop can stand in for the ribbon. Your result is your average error as a percentage of the ribbon’s length, plus your lean — the average error with its direction — placed among the 50 adults in Learmonth and colleagues’ open data.

It is not a neurological test and it cannot screen for neglect or anything else. Eight cuts make a much jumpier lean than the 216 lines each person bisected in the study, and they clicked with a mouse while you drag with a finger, so the comparison is a rough guide. No study we could find reports how far off people are either way, so the tiers for ‘% off’ are the site’s own. Whichever way you lean, it is normal.

What the test measures

Two numbers from one simple task: how close you get to the middle, and which way you lean.

The task

  • Line bisection, the classic task behind pseudoneglect research: cut each ribbon exactly in half
  • Eight ribbons in four lengths, each once left and once right of the screen’s centre
  • Four steps, each hanging the ribbon further off the middle of the shopfront
  • Drag anywhere to slide the scissors, or use the adjust bar and arrow keys; the scissors cut exactly on the dashed line

Your result

  • Your average error, as a percentage of each ribbon’s length
  • Your lean: the average error with its direction, and how many of the eight cuts went each way
  • Where that lean sits among the 50 adults in Learmonth et al. (2015), counted from the study’s open data rather than from a bell curve
  • A cutting report with all eight cuts lined up, a shareable card and a link that challenges a friend

Before you start

  • About two minutes, eight ribbons
  • Hold your phone straight; which hand you use and where your finger rests nudge the result
  • Works on phones and computers; sound is optional

Line bisection FAQ

Is this test free? Do I need to sign up to see my result?

Yes, it’s free, and there’s nothing to sign up for: no account, no email, no payment. Your result appears on this page the moment you finish, and you can share it or play again straight away.

What is a line bisection test?

A line bisection test asks you to mark the middle of a horizontal line. Neurologists use it to look for neglect, a loss of attention to one side of space after some brain injuries; in healthy people the same task shows pseudoneglect, a much smaller and quite consistent bias. This version swaps pen and paper for a ribbon and a pair of scissors.

Which way do most people lean on a line bisection test?

The cutting report tells you after your eighth ribbon, along with the reason. Knowing which way people usually drift would change where you cut, so the page keeps it until you have finished. The answer comes from decades of studies, summed up in Jewell and McCourt’s 2000 meta-analysis of line bisection in healthy people, and from the open data of Learmonth and colleagues’ 2015 study.

How far off the middle do most people cut?

The cutting report shows it after your eighth ribbon, with your own lean placed among the 50 people in Learmonth and colleagues’ 2015 study. They were right-handed young adults who clicked the middle of lines 23.5 cm long with a mouse, over 216 lines each. The page keeps their typical lean and its direction back until you have cut, so it can’t steer your scissors.

Is it bad to lean one way on a line bisection test?

No. Healthy adults in Learmonth et al.’s sample leaned both ways, and the result page shows how many went each way. With only eight cuts, your lean also swings more from one run to the next than the study’s averages over 216 lines did. A lean in this game is not a symptom of anything; if you notice real trouble paying attention to one side of space, that is a question for a doctor, and this test can’t check for it.

How is my line bisection result compared with other people?

Only your lean is compared. It is ranked against the 50 people in Learmonth et al. (2015) by counting how many leaned less far than you, with no bell curve assumed. Your ‘% off’ has no published norm, so its tiers — under 1%, under 2%, under 4% and more — are the site’s own rough guide. The comparison group was right-handed and used a mouse.

How long does the line bisection test take?

About two minutes: eight ribbons, one cut each. The line bisection test works on phones and computers; on a phone you can drag anywhere on the screen to slide the scissors, so your finger doesn’t have to cover the ribbon.

Where the numbers come from

Your lean is ranked against the 50 adults in Learmonth et al. (2015), computed from the study’s open data: each person’s mean over two sessions, as a percentage of line length. No study we found reports each person’s error regardless of direction, so the ‘% off’ tiers are the site’s own. The site does not publish its own players’ data.