Effects of Attentional Sets in Sustained Inattentional Blindness
 
 
This page contains some sample demonstrations from the following paper:
Most, S. B., Scholl, B. J., Clifford, E., & Simons, D. J. (2005). What you see is what you set: Sustained inattentional blindness and the capture of awareness. Psychological Review, 112(1), 217-242.
The demonstrations are provided as Quicktime movies, which can be downloaded or viewed directly in most web-browsers. (To download a free Quicktime player, go here.) 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.  
 
The experiments reported in this paper explored several different types of effects of attentional set on the conscious perception of unexpected events in these displays. This is part of a a larger theoretical and experimental attempt in this paper to relate and contrast two traditionally separate research programs: inattentional blindness and attention capture. Insights about the roles of visual properties and top-down attentional set can be drawn from research on attention capture, which traditionally employs implicit indices (e.g., response times) to investigate automatic shifts of attention. Yet, because attention capture research usually measures performance, whereas inattentional blindness research measures awareness, the two fields have existed side by side with no shared theoretical framework. Constructing that framework requires that insights from one literature be related to and tested in the other, and in this paper we set this process in motion. We propose a theoretical unification influenced by a "perceptual cycle model" (Neisser, 1976), and we then systematically adapt several of the most important effects from the attention capture literature to the context of sustained inattentional blindness experiments. Although some stimulus properties can influence noticing of unexpected objects, the most influential factor affecting noticing is a person's own attentional goals. We conclude that many -- but not all -- aspects of attention capture also apply to the capture of awareness, but that these two classes of phenomena remain importantly distinct.  
 
Attentional Set Demo: UE = Black Circle (3.8 MB)  
In a previous study (Most et al., 2001, Psychological Science), we showed that luminance similarity plays a role in mediating the conscious awareness of UEs in this paradigm: Subjects were much more likely to notice the UE when it was similar in luminance to the attended items, and much less likely to notice it when it was featurally dissimilar to the ignored items (where these two factors are unconfounded). In this paper we extended these results to multiple featural dimensions, even while using identical displays. In this movie the subjects can be instructed to track either the discs, the squares, the white items, or the black items. When the black circular UE appeared, subjects who were either the discs or the black items were far more likely to see it.  

Sudden Onset UE (2.2 MB)
Gradual Onset UE (2.4 MB)  
This work also demonstrated that sudden onsets do not always result in conscious awareness of UEs, even though they do capture attention in other paradigms.