This unique laboratory measures legibility in terms of the maximum distance at which people can clearly read a message. That distance is inversely related to the size of the retinal image and to the number of neural pathways needed for recognition. More legible messages require fewer neurons to convey the information and can be read at greater distance. The results can be directly compared with legal criteria for visual acuity, which are also based on distance - 20/20 vision means being able to see at twenty feet what the average person can see at twenty feet. The method can also measure the visual effectiveness of any type of color graphics including symbols, markers, line drawings, and pictures. This enables optimizing various design aspects such as shape, font, layout, size, and color combinations. The words or graphics may be in print (up to 60 x 60 cm), or electronic images, or rear-projected slides. An eight-meter, fully automated track (optically extendable to 48 meters) and ready access to students as observers makes possible commercial testing of packaging and advertisements. A goal is to develop national standards for the visual effectiveness of signs and messages important to health and safety.
 
 
 

HISTORY

In 1989, Health Canada's Office of Tobacco Control asked Professor Thomy Nilsson of UPEI's Psychology Department to devise a method of measuring the legibility of warnings printed in color on cigarette packages - a method that would withstand legal challenge. While there were standards for legibility of print, these pertained only to words in black and white. The typical methods of measuring legibility in terms of reading speed were not representative of every day life. Furthermore, differences in the response rate of color vision mechanisms could cast doubt on the validity of such measurements. Based on experience with various methods of measuring visual performance, Nilsson suggested using recognition distance - the same method as is used to define visual acuity in the 20/20 system. A contract was issued to evaluate the distance method. In collaboration with Dr Terry Percival, distance testing indicated that the psychophysical method-of-limits produced reliable results that were consistent with subjective evaluations of legibility and also revealed that surface gloss affected legibility as much as color. With the assistance of Drs. Percival and Richard St Jean of the Psychology Department, a subsequent contract to Dr. Nilsson enabled renting space from UPEI, renovating it into a suitable laboratory, and building a fully automated, 8-meter test track. The testing showed beyond any doubt that the warnings on many brands of cigarettes were printed in color combinations that made them very difficult to read. The terms of that contract stipulated that when the testing was completed, the facility would be lent to UPEI. In May 1992 the Honourable George Proud, MP Hillsborough, on behalf of Health Canada turned the facility over to UPEI's President Dr. C.W.J. Eliot.

In one of the first UPEI-Industrial partnerships aided by ACOA, Tri*Ad Designs subcontracted the Legibility Lab to provide guidelines for the design of effective signs, computer displays, and markings for the Canadian Space Agency and to demonstrate the commercial potential of the Lab for evaluating commercial designs. (Tri*Ad Designs is a small, innovative, graphics design "house" in Winsloe, PEI. For more information contact its president, Glenda Clements-Smith.) clements@upei.ca
This work led to the re-discovery of color combinations for printed words and graphics that were more effective than black and white. Though contrary to all current research, which measured legibility in terms of reading speed, the measurements based on distance thresholds did not bypass the contribution of the slow-conducting neural pathways for color information. This contract provided the Lab with international standard light sources to simulate various daylight and indoor illuminations and enabled development of the parallax-free, binocular viewing system that extends the effective track length to 48 meters. Further work under this contract demonstrated that distance thresholds provided a quantitative means of measuring the effectiveness of various computer imaging enhancement techniques. A project for the PEI Potato Marketing Board demonstrated its suitability for measuring the visual effectiveness of consumer packaging designs.
 

RECENT WORK

Further contract work for the Office of Tobacco Control in 1999 measured the visual effectiveness of new cigarette package warnings of various sizes with various types of graphic supplements. Health Canada believes that these quantitative data will stand the legal challenges of tobacco companies and enable requirements for more effective warnings.

A project for NATO enabled comparing the distance threshold techniques with the best alternatives for measuring the effectiveness of camouflage. Using the test track, five UPEI students after 2 training sessions were able to discriminate significantly more degrees of camouflage than were 60 NATO trained observers using search time; both groups viewing the same projected pictures of tanks and armoured personnel carriers in mixed terrains.

Current work is examining how different stroke widths of letters affects legibility in all combinations of the six primary colors. The purpose is clarify some differences in the maximally effective color combinations of words, symbols and line-drawings. Apart from their practical implications, these results may provide some insight into the receptive-field mechanisms of color vision.

The Legibility Testing Laboratory is also used for student labs in the Psychology 411 - Visual Perception course and for student research projects. One of these led to a current collaborative research project with Adrian Schwaninger at the University of Zurich to combine reaction time and distance measurements to estimate the total amount of neural processing involved in perception.

INQUIRIES

For commercial testing and inquiries about research applications, please contact:

Dr. Thomy Nilsson, Department of Psychology nilsson@upei.ca

phone: (902) 566-0489; fax: (902) 628-4359