Noticing of an Unexpected Event is Affected by Attentional Set for Expected Action

Inattentional blindness (IB) occurs when we fail to become aware of an unexpected stimulus because our attention is devoted to another task or object (Mack & Rock, 1998). IB can affect behavior in a variety of situations, including driving, identifying a specific person in a crowd, and recognizing when to make a particular play in games such as handball (Memmert & Furley, 2007; Strayer, Cooper, & Drews, 2004). How well the unexpected object or event fits the attentional set of the observer also can affect the rate of noticing (e.g. Most, Scholl, Clifford, & Simons, 2005), but the work in this area is generally limited to attentional sets based on physical features of characters or objects moving around on a screen or the meaning of words and simple pictures being presented on a monitor. In this study, we expand the work in this area to include attentional sets for actions of a target actor in a dynamic video showing typical activity on a college campus. In the present study we attempted to investigate the effect of attentional set for actions of a target person on noticing in a simulated surveillance video. Simons and Chabris (1999) cite the common example of individuals focusing much of their attention on finding a seat in a crowded movie theater that they miss their friends frantically waving their arms trying to get their attention. Although IB does not lead to serious consequences in this example, other applications of IB may. For instance, Strayer, et al. (2004) found that when participants were engaged in a driving simulation while talking on a cellular telephone they were more likely to fail to notice objects from the driving scene. Even if participants looked directly at objects in the driving scene, they were less likely to create a memory of those objects that was accurate and easily retrievable if they were talking on a cellular telephone. Others have also found inattentional blindness in driving scenarios (McCarley, Vais, Pringle, Kramer, Irwin, & Strayer, 2004; Most & Astur, 2007). Finally, Haines (1991) found IB in pilots using a flight simulator. Two of eight pilots failed to see another airplane blocking the runway and attempted to land the airplane because they were attending to flight instruments. The automobile driving studies and Haines' experiment illustrates how IB can have serious consequences. To build upon Neisser (1979), Simons and Chabris (1999) conducted an IB study in which they manipulated the similarity of the attended object to the unexpected stimulus, task difficulty, and the nature of the unexpected stimulus. Participants viewed videos of two teams consisting of three members (one wearing black shirts and one wearing white shirts) passing a basketball back and forth while moving in a random circular fashion. Approximately 44-48 sec into the video, a woman wearing a gorilla suit or a woman carrying an umbrella entered the screen from the left, walked through the two teams, and exited the screen on the right. The participants were instructed to count the number of passes made by either the white team or the black team. Their results showed that 46% of participants failed to see the unexpected event, with the umbrella woman being noticed more often than the gorilla. When participants were attending to the black team, the gorilla was more likely to be noticed, which demonstrates how attentional set can affect noticing. Subsequent research has looked more closely at the effect of attentional set (e.g. Most et al., 2001, 2005) and found that unexpected objects fail to capture awareness when they are inconsistent with the participants' attentional set. They found these results by manipulating luminance, color, and shape of geometric objects (Most et al., 2001, 2005), racial facial features of disembodied heads (Most et al. 2005) and the color of a traffic signal and an oncoming motorcycle (Most & Astur, 2007). Most et al. (2005) adapted Neisser's (1976) Perceptual Cycle Framework to account for attention capture and capture of awareness. …