Are the horizontal lines in this image parallel or do they slope down?
This is a popular, simple optical illusion that uses black and white effectively to confuse our perceptions of what we are seeing. Because we are trying to rationalise either the black vertical lines or white vertical lines, we cannot make sense of the untidiness of the columns and, to our eyes, the horizontal lines are sloping downwards. Our eyes naturally follow the powerful vertical lines.
In fact, the horizontal lines themselves are perfectly straight and measuring them would prove that they do not slope down at all.
Are the horizontal lines parallel or do they slope?
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