American Academy of Optometry
American Academy of Optometry
October 12, 2015
1 min read

Including symbols in license plates improves recall

You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

We were unable to process your request. Please try again later. If you continue to have this issue please contact

NEW ORLEANS – Substituting a symbol for a number in a six-character license plate was found to significantly improve short-term recollection as compared to conventional alphanumeric-only designs, according to a presenter here at an American Academy of Optometry-sponsored press conference.

Alan L. Lewis, OD, PhD, FAAO, and colleagues from the New England College of Optometry evaluated the EZ-ID, a proposed license plate design that uses a heart, star, triangle or square in place of a number or letter in a six-character license plate, as a method for making license plates more recallable.


Alan L. Lewis

At the press conference, Lewis shared the impetus for the proposed design change.

“A murder occurred in Massachusetts where a lot of people saw the car, but couldn’t identify the license plate,” he said.

The researchers randomly selected 10 six-character Massachusetts license plates from a sample of cars. Five of the plates were modified to replace one of the two middle characters with a symbol.

Twenty-eight subjects sat 1.5 meters away from a monitor, and 10 different plates were displayed for 3 seconds each, Lewis explained.

“A distractor photo of a president was shown to get them to think about something else, then they were asked to repeat the license plate,” he said.

“Forty-three percent of all plates were correctly identified,” Lewis said. “Sixty-one percent identified more plates with symbols. Only 7% of plates with alphanumerics were correctly identified.”

He said that 53% of plates containing symbols and 33% of plates containing only alphanumerics were completely correctly identified.

“Ninety-six percent of all symbols were correctly recalled,” Lewis said, “and they were always in the right position. This is a great ability to reduce the gamut of potential vehicles with those plates.”

He concluded: “We believe the inclusion of symbols in a six-character license plate increases the recall of a complete license number. We are moving ahead to try to convince legislators to change license plate design.” – by Nancy Hemphill, ELS, FAAO

Disclosure: No products were mentioned that would require financial disclosure.