Inattentional blindness is a failure to notice stimulus directly in one's perceptual field. Many refer to it as "looking without seeing." It is also referred to as perceptual or change blindness. This concept was discovered by Arien Mack and Irvin Rock while studying the relationship of attention to perception. Their studies revealed a significant percentage of subjects were affected by this phenomenon.
The most common causes of inattentional blindness are conspicuity, mental workload, expectation, and attentional capacity. Inconspicuous objects due to their physical characteristics or unfamiliarity fade into the background. During heavy cognitive load, the brain allows more unfiltered information to pass through. When expecting a specific result, the mind bypasses what it perceived as irrelevant information. Attentional capacity refers to the amount of work a task requires. Uncommon tasks place greater load on the mind; therefore, more information is bypassed. Although this may seem counter-intuitive, the brain is limited on resources. It must assimilate only selected pieces and release the rest. Dams are built upon the same concept.
Some people are not educated to the theory of inattentional blindness and others falsely believe it does not affect them. Yet many of those same individuals are fascinated and entertained by magicians. Misdirection depends on inattentional blindness. It's what makes magic seem like... magic. How does this affect software design? How can it be combated?
The first step is personal education. The information above is a good start, but further exploration is recommended. The books "Inattentional Blindness" and "The Invisible Gorilla" provide excellent discussion on the topic. Additionally, "The Invisible Gorilla" has a website
filled with video examples along with the video that inspired the book. These only take a few minutes to watch but can be eye opening.
The second step is recognizing how it affects design. Remember these tips:
- Error messages are an unexpected result; therefore, they must be prominently displayed. Proper animation and user action may be required to grab a user's attention.
- Validation messages are similar to errors in that users expect their input was correct. A simple asterisk or red coloring may not suffice. A proper call to action must be visible.
- Focusing on maximizing screen real estate is not realistic because a user doesn't focus on the entire screen.
- Increased cognitive load decreases user awareness; therefore, screens must be kept simple and straight forward. Complex data entry should be broken up into smaller steps. Consider using multiple screens, collapsible areas, or wizards.
- Take advantage of familiarity This is where touch applications excel. They utilize common swipe techniques to make an application feel more intuitive.
- Take further advantage of familiarity by connecting directly with users. For instance, provide a hyperlink to a user's settings by using their name as the text. Users are naturally drawn to their own names.
- Attentional capacity is very important in design. Seldomly accessed screens require simpler designs due to their unfamiliarity. Commonly used areas can have increased functionality due to their lower cognitive load.
There is no silver bullet for inattentional blindness It affects everyone to varying levels. It cannot be prevented, but with proper attention during design, it can be overcome.