An analysis of photos of people and objects in motion revealed a common left-to-right bias.

Psychologist Dr Peter Walker of Lancaster University said this widespread evidence for such a left-to-right bias could indicate a possible fundamental bias for visual motion, and would explain why all the main characters in the side-scrolling video games popular in the 1980s and 1990s  (eg Super Mario) run from left to right. 

He inspected thousands of items in Google Images for his research published in Perception.

He said: “What artistic conventions are used to convey the motion of animate and inanimate items in still images, such as drawings and photographs? One graphic convention involves depicting items leaning forward into their movement, with greater leaning conveying greater speed. Another convention, revealed in the present study, involves depicting items moving from left to right.”

However, this bias does not apply to people or objects which are stationary.

“Whereas a rightward bias is found for photographs of animate and inanimate items in motion (more so the faster is the motion being conveyed), either no bias or a leftward bias is found for the same items in static pose. This could indicate a fundamental left-to-right bias for visual motion.”

This left-to-right bias is also observed when designers italicize text to convey notions of motion and speed.

It even applies to typography in Hebrew where the reader’s eyes scan from right-to-left.

“It was the inspection of the availability of italic fonts in Hebrew that suggested an additional artistic convention for conveying motion, based on a fundamental bias, confirmed in the present study, for people to expect to see, or prefer to see, lateral movement (real or implied) in a left to right direction, rather than a right to left direction.”