The invisible gorilla revisited: using eye tracking to investigate inattentional blindness in interface design

Interface designers often use change and movement to draw users' attention. Research on change blindness and inattentional blindness challenges this approach. In Simons and Chabris' 1999, "Gorillas in our midst" experiment, they showed how people that are focused on a task are likely to miss the occurrence of an unforeseen event (a man in a gorilla suit in their case), even if it appears in their field of vision. This relates to interface design because interfaces often include moving elements such as rotating banners or advertisements, which designers obviously want users to notice. We investigated how inattentional blindness affect users' perception through an eye tracking investigation on Simons and Chabris' video as well as on the web site of an airline that uses a rotating banner to advertise special deals. In both cases users performed tasks that required their full attention and were then interviewed to determine to what extent they perceived the changes or new information. We compared the results of the two experiments to see how Simons and Chabris' theory applies to interface design. Our findings show that although 43% of the participants had fixations on the gorilla, only 22% said that they noticed it. On the web site, 75% of participants had fixations on the moving banner but only 33% could recall any information related to it. We offer reasons for these results and provide designers with advice on how to address the effect of inattentional blindness and change blindness in their designs.