Effects of Proximity in Sustained Inattentional Blindness
This page contains some sample demonstrations from the following paper:
Most, S. B., Simons, D. J., Scholl, B. J., & Chabris, C. F. (2000). Sustained inattentional blindness: The role of location in the detection of unexpected dynamic events. Psyche, 6(14).
The demonstrations are provided as Quicktime movies, which can be downloaded or viewed directly in most web-browsers. These movies are a bit large and choppy, but they should be sufficient to illustrate the basic conditions. If the movies seem too choppy or if the lines are not drawn smoothly, try downloading the movies and playing them off your local hard drive.  
In typical 'inattentional blindness' phenomena, observers fail to perceive objects in briefly flashed scenes under certain conditions. We have generalized and explored this phenomenon in a dynamic computer-controlled context, with displays containing independently and unpredictably moving white and black shapes. In these trials, the observer must count the number of times that the white shapes (but not the black shapes) bounce against the edges of the display. On the third trial, an 'unexpected event' (UE) occurs: a new shape suddenly enters and moves across the display for 5 seconds. Even when the UE has a novel shape, color, luminance, and type of trajectory, 30% of subjects completely fail to perceive it! (In contrast, all observers see the UE when not engaged in an attentionally demanding task.) This phenomenon underscores the importance of attentional selection as a 'gateway' to conscious perception. This method allows us to parametrically explore the visual features which capture attention and thus result in conscious perception.  
This paradigm also allows us to explore other factors mediating attentional capture by a UE, such as its spatial proximity to the locus of attention. Here subjects must count the number of times that the white objects (but not the black objects) impact the horizonatal line running through the middle of the display. On the third trial, the UE appears as before, but can appear on the line, near the line, far from the line, or even beyond the area in which the items move. The farther from the locus of attention, the less likely that subjects will notice the UE.  
UE appears on line (1.5 MB)  
UE appears on line (Smaller 388 KB movie)  
UE appears far from line (1.5 MB)  
UE appears far from line (Smaller 392 KB movie)