Competing studies suggest that millennials may be reading more or fewer books than their older counterparts, but no matter what your choice of literature, we’re reading much more text at a glance than we ever have, in our cars, on our phones and on our wearable technology.
A new study from the MIT AgeLab suggests that font type, size and color all play a critical role in how easily we can understand that text. It also notes that our degrading ability to decipher that text happens at a much younger age than we thought.
Whether or not we pick up more or fewer copies of the latest best-seller, we are inundated with text every moment of our waking lives, and we’re required to understand more of it more quickly than ever.
If you’re not sold on that theory, take a look at these two Chevrolet Impala instrument panels, separated by 40 years:
There are only four critical information sources in front of the driver: vehicle speed, fuel level, wiper controls, lights. The radio has numerals as a matter of convenience, but it, along with the light controls and wiper controls, are meant to be operated without the driver taking her eyes off the road.
Now take a look at the dashboard on the 2016 Chevrolet Impala:
The infotainment screen alone has three layers, with multiple menus in each layer.
All of this information is meant to be read and processed at a glance, but manufacturers of automobiles, mobile devices and wearables have little to no science behind their decisions on fonts, font size or font and background color.
The new paper entitled “Utilising psychophysical techniques to investigate the effects of age, typeface design, size and display polarity on glance legibility” provides the information that product planners and designers need to understand as they pack more and more glance-based information in front of drivers.
The paper builds upon an ongoing collaboration between the MIT AgeLab and typeface technology specialist Monotype. The paper directly extends research that was first conducted under conditions of simulated driving.
The newest study tests the legibility of two different typefaces:
A curvy, open, “humanist” style called Frutiger:
…and a more geometric, uniform “square grotesque” typeface called Eurostile.
“We picked these typefaces because both are used frequently in automotive applications, where reading at a glance is key,” says Dr. Jonathan Dobres, a research scientist at the MIT AgeLab.
The study compared the legibility of these two typefaces in several conditions: White text on a dark background, black text on a white background, and both conditions in 3mm and 4mm font size. The study included participants between the ages of 20 and 65.
“We tested legibility by presenting single words on a screen for very brief periods of time, simulating glance behavior, and calculated the amount of time needed to read words accurately under a given combination of typeface, size, and whether the text was black on a white background or white on a black background,” says Dr. Bryan Reimer, research scientist at the MIT AgeLab and Associate Director of the New England University Transportation Center. “More legible typographic conditions should require less time for accurate reading. This testing method allows us to rapidly compare many different design combinations.”
The new work extends earlier results by showing that the Frutiger typeface required less time for reading accuracy versus Eurostile in every condition tested, but the key finding in this study was that black-on-white text could be read faster than white-on-black.
The current trend in most applications — automotive, mobile device and wearable device — is to put white text on a black background, but it’s almost purely that: a trend. “White-on-black text is pretty common in automotive interfaces, since it limits the amount of light in the cabin and has a somewhat more “futuristic” feel,” says Dr. Dobres. “This research suggests that presenting text in these colors can make text somewhat harder to read.” Ongoing work is assessing the generalizability of these results to different ambient lighting conditions.
“We’re seeing an aging eye problem in participants in their 30s,” says Dr. Reimer. “By failing to balance graphic design with the practicalities of glance-based text recognition, we’re penalizing older adults, but ‘older’ isn’t as old as you think. What we see across all of our work, is that the complexities involved in optimizing legibility are immense, and the literature guiding decisions in this new world of glance based design relatively scarce.
“This lack of guidance, thus creates a need to empower graphical designers and user experience professionals with objective data on how they may best balance decisions that impact textual communication in information rich digital contexts like the car, phone and wearable.”
The study also found that regardless of color or typeface, a larger size is easier to read. What’s surprising, though, is how much larger.
The difference of just 1mm in font size makes text easier to glance at and process. The tested 3mm font equates to about 8.5 point type, while the 4mm size is a bit larger than 11 point type.
“When text size shrank from 4mm to 3mm, reading times increased for both typefaces, but much more so for Eurostile compared to Frutiger,” says Dr. Dobres. “Eurostile’s rigid, geometric design held up much more poorly at the smaller text size, appearing more noisy and ambiguous.
“A designer might reasonably think, ‘Four millimeters or three, that’s not much difference,’ but this work argues that even a relatively small decrease in size can produce a relatively big jump in reading times,” he says.
The most notable part of the study centered on age, though. It’s long been assumed that a subject’s age has a significant impact on reading function. The study did note that reading times increased by about 81 percent between the ages of 20 and 65, indicating that older participants lose contrast sensitivity and visual acuity. The surprise, though, was the difference in performance emerged in participants as young as 30. Participants in their 20s weren’t strongly affected by either Frutiger or Eurostile fonts, but after 30, the typeface made a significant difference.
“We’re seeing an aging eye problem in participants in their 30s,” says Dr. Reimer. “By failing to balance graphic design with the practicalities of glance-based text recognition, we’re penalizing older adults, but ‘older’ isn’t as old as you think.”
The least legible combination of font, color and size was Eurostile set against a dark background at a 3mm text size made reading speed worse with age. Reading times increased for every design condition as participants got older, but the conditions that had the highest average reading time also saw the fastest age-related increase.
The results of this work indicate that even subtle design choices, such as a choice between two sans serif typefaces, can dramatically affect the visual experience of the person doing the reading. For older readers or people with even subtle visual impairments that come on after age 30, the effects are amplified.