Selective Visual Attention: Computational Models and Applications

1.3 Change Blindness and Inhibition of Return

There are two phenomena related to visual attention that people experience every day. One is that a person turns a blind eye to some change in their environment. The phenomenon is called change blindness. The other is that attention focus never fixes a location for a long time, and there exists a mechanism to inhibit the fixation returning back to the original location. In the following sections, we explain the two phenomena.

1.3.1 Change Blindness

Change blindness (CB) is defined as the induced failure of observers to detect a change in a visual display [39]. This invisible change often happens in the alternating images with a blank fields (about 80 ms or more). Two nearly identical scenes with a certain background change appear one by one. The changes can be noticed easily since the change location can be popped out at alternate times. However, when a transient blank frame (more than 80 ms) is inserted between the two nearly identical scenes, the change is often not noticed by observers. In another setting, two nearly identical pictures with some changes are displayed side by side as shown in Figure 1.5. Pointing the difference between them at a glance is difficult. Once the large change is detected in Figure 1.5, most people are amazed at failing to notice it. The cause of change blindness is human selective visual attention. Some changes in no-attention regions are ignored, as shown in Figure 1.3, in which many regions of the family ...