A THOUGHT-provoking optical illusion has left many questioning their own brains.
Most optical illusions confuse the human brain via the use of color and lines – and one simple image proved this is the case.
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Known as vertical-horizontal illusions, this specific illusion comprises a horizontal line with a bisecting vertical line.
It was developed in 1858 by German psychologist Wilhelm Wundt, who is seen today as one of the modern fathers of psychology.
There are several different variations of the vertical–horizontal illusion.
The three main configurations are the L configuration, the plus (+) configuration, and the inverted-T configuration.
Of these three, the inverted-T configuration produces the highest illusion magnitude.
At first glance, the bisecting vertical line appears around 30 percent longer than the horizontal line, according to Wundt.
However, the lines are both exactly the same length – to many people’s surprise.
The exact reasoning behind this phenomenon is not clear, but several possible explanations have been thrown out there.
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Some experts have suggested that this is due to the positioning of the vertical line, which triggers our depth perception.
In turn, our minds may perceive the vertical line as being further away than the horizontal line, and therefore longer.
A second explanation suggests that line length depends on how much effort it takes to move our eyes over the lines.
Because Westerners are used to reading from left to right, it could require slightly more effort than reading up and down.
As a result, this could make the vertical line appear longer than the horizontal line of the same length.
Some research has claimed that people who live in urban areas are more susceptible to Vertical-Horizontal illusion than those in rural environments.
Interestingly, that 1977 study found that the urban group was more susceptible to the L-form vertical-horizontal illusion, but not to the inverted-T form.
