Eighty percent of arguments over graphics start from the incorrect assumption that what my brain sees is the same as what your brain sees. (Okay, I made that percentage up… As far as I know there's been no definitive study on the root causes of arguments over graphics.)
What we do know is that certain conditioning, physical, and genetic attributes account for variations in visual perception. Recognizing even common phenomena such as change blindness, color blindness, and blind spots can fortify our design decisions to help learners “get” key instruction.
Change Blindness
Some current theories about how we process visual data explain why all of us are often slow to register changes in familiar objects. According to the theories of Jeff Hawkins and others (see Resources), as soon as identification of an image is authenticated, the brain moves on to other visual stimuli. If they could talk, the brain's visual processing munchkins might sound like this:
This theory goes a long way in explaining why we fail to recognize the aging face in the mirror until one day, the brain munchkins go:
For designers, the take-away is that we need to be wary when we assume that our learners will register what is new in a familiar diagram or image. This is especially true when we rely on over-exploited visual metaphors, such as the ubiquitous pyramid.
Color Blindness
Most humans have three types of cones in our retinas which let us register color and spatial acuity. But men who are color blind have only two types of normal cones and a third, mutated type and cannot distinguish clearly between red and green. Designers can avoid requiring these learners to discriminate between red and green by using redundant cueing such as arrows, dark outlines, or even text labels to reinforce the distinction.
Interestingly, recent research has found that a small but statistically significant percentage of women have an additional type of cone, giving them the ability to see a greater variation in color. These tetrachromats have been able to discriminate up to 10 bands of color in prisms (rainbows) rather than the mere seven bands the rest of us register. So the next time you get in an argument with a woman who insists that there is another shade of green, assume she’s right.
Blind Spots
As one final example: All of us have a visual blind spot – that spot on the retina where the optic nerve and blood leave the eyeball and where there are neither rods nor cones to receive visual stimuli.
But our brain munchkins conveniently make best guesses and clone the background image. We “see” a full picture without any black holes, but we may miss key visual details located in that space, especially if audio or other instruction directs our attention to another part of the screen.
So what does all this mean for our design of instructional graphics? We need to:
- Avoid overused graphics to communicate new information. If you have to use them, be sure to use new graphic elements (color, contrast, or formatting) to highlight what’s new.
- Be wary of arguments over colors. Remember rods and cones. Your counterparts may simply not be equipped to see everything you do or you them. Make sure your instructional graphics do not rely solely on color for discrimination tasks.
- Provide ample time to view complicated graphics, especially in videos. Give your learners time and cues to absorb all the details in the visual field. Otherwise, with too brief an exposure, the brain will fill in that blind spot to the best of its ability… but what it fills the spot in with may not be your intention.
In sum, we need to avoid relying on our own perceptions of colors, shapes, and arrangements as the only measures of what our learners will see. Design instructional graphics that succeed regardless of visual perception differences in change blindness, color discrimination, or blind spots.
Resources
For more on change blindness:
Hawkins, Jeff (2004). On Intelligence. New York: St. Martin’s Griffin, p. 129
For more on the tetrachromats:
Greenwood, Veronique. June 18, 2012. “Humans with Super-Human Vision,” Discover Magazine. http://discovermagazine.com/2012/jul-aug/06-humans-with-super-human-vision/
http://news.softpedia.com/news/Half-of-the-Women-See-More-Colors-than-the-Rest-of-the-People-58351.shtml
For more on the blind spot:
Eagleman, David, 2011. Incognito: The Secret Lives of the Brain, New York: Pantheon, p. 24
Gregory, Richard and Cavanagh, Patrick (2011). “The Blind Spot” Scholarpedia, 6(10):9618. http://www.scholarpedia.org/article/The_Blind_Spot