Inattentional Blindness

In document An attentional theory of continuity editing (Page 40-44)

Chapter 2: Background

2.3 The psychological effects of discontinuities

2.3.3 Inattentional Blindness

When a sudden salient sensory event (such as the abrupt onsets caused by a continuity cut) fails to capture attention it is described as inattentional blindness (Mack & Rock, 1998). The most famous examples of inattentional blindness are Simons & Chabris’ Umbrella Woman and Gorrilla studies (Simons & Chabris, 1999)14. The Umbrella Woman study presented two simultaneous semi-transparent

40 visual scenes in the same display15. In one scene a group of people wearing white play basketball. In the other scene, a group in black are also playing basketball but 45 seconds into the game a woman carrying a black umbrella walks through their game (see Figure 2-4; a). When subjects are instructed to count the number of times the team in white pass the ball 57% fail to notice the umbrella woman (Simons & Chabris, 1999).

Even more impressive is the Gorilla study. Simons & Chabris (1999) constructed a similar film depicting two teams playing basketball but this time they were both filmed at the same time (not two films overlaid; see Figure 2-4; b). In this film, when a man wearing a black gorilla suit walked through the game mid way through 73% of viewers failed to notice him (Simons & Chabris, 1999). When shown the film again all subjects notice the gorilla and are stunned that they failed to notice him the first time (Simons & Chabris, 1999).

Figure 2-4: Simon and Chabris' (1999) inattentional blindness study. Top row shows the two superimposed films from the Umbrella woman experiment. Bottom row shows a series of frames from Gorilla Study.

15 This is a version of the selective looking paradigm, a visual version of the dichotic listening task (Becklen & Cervone, 1983; Neisser, 1979; Neisser & Becklen, 1975).

41 These examples of inattentional blindness highlight the importance of viewing task for the detection of unexpected sensory events (Simons, 2000). When subjects were instructed to count the passes of the white group only 8% noticed the black gorilla but this increased to 46% when subjects followed the black team (Simons & Chabris, 1999). The subject’s use of the colour black to direct their attention within the scene meant that they were also attending to the gorilla. The task dictated how they should focus their attention and filter out irrelevant visual features. This specificity has been described as a viewer’s attentional set (Folk, Remington, & Johnstone, 1992). The main technique used for highlighting the effect of attentional set is the pre- cueing paradigm (Folk & Remington, 1998; Folk et al., 1994; Folk et al., 1992; Gibson & Kelsey, 1998). This paradigm asks subjects to search for a target that differs from all other objects in the display according to a specific feature (e.g. the colour green). If before the display appears the location of the target is pre-cued using the same feature (e.g. a green position marker), subjects will be quicker to identify the target even though they are informed that the pre-cue is equally as likely to appear anywhere in the display (Folk & Remington, 1998; Folk et al., 1992). If the pre-cue differs to the target’s defining feature (the pre-cue has a sudden onset) it will have no effect on performance (Folk et al., 1992).

It appears that the attentional set can occur at many levels. It can be location based or object based (Yantis & Jonides, 1990), dynamic or static (Folk et al., 1994), unique items or a specific conjunction of object features (Folk & Remington, 1998). If the distracting object shares the features at exactly the right level as that specified by the attentional set then capture should occur. Any deviation from this and the likelihood of attentional capture decreases (Most, Scholl, Simons, & Clifford, 2005; Simons, 2000).

This evidence suggests that some bottom-up properties such as salience or sudden onsets, influence the likelihood that an unexpected object will capture attention, but the most important factor appears to be the attentional set adopted by the individual (Simons, 2000). In the absence of an attentional set abrupt onsets appear to be the

42 only reliable feature that will capture attention (Franconeri et al., in press). This has been explained as due to a default attentional set that has survival benefits (Gibson & Kelsey, 1998). In the real-world, objects that suddenly change colour, brightness, or shape rarely pose any danger to the observer (if the occur naturally at all). By comparison, the sudden appearance of an object or its sudden movement could indicate that a predator is about to attack. Including these features in a default attentional set that allows the feature to capture our attention would make us more capable of surviving in hostile environments. Also, limiting the incidence of attentional capture through the use of an attentional set also ensures that when attention is focussed it is not involuntarily captured. These two processes, voluntary focussing and involuntary capture, and their coordination is key to visual attention (Allport, 1989).

Applying this idea of attentional sets to film viewing it becomes clear that the orienting response potentially triggered by every cut (Geiger & Reeves, 1993; Lang et al., 1993; Singer, 1980) can be attributed to this default attention to abrupt onsets (Franconeri et al., in press). However, it appears that this level of attention capture is generally implicit as continuity cuts do not lead to awareness of the editing (d'Ydewalle & Vanderbeeken, 1990; Schröder, 1990).Whilst there does not currently exist a clear understanding of why certain visual events lead to implicit and others explicit capture there does seem to be an indication that relevance to attentional set is a factor (Most et al., 2005). If a visual event is relevant to a viewer’s current attentional set there is a higher probability that they will become aware of the event. However, this effect is modulated by the availability of attention. If attention is engaged by another task the likelihood of capture is reduced (Simons, 2000).

This interpretation of inattentional blindness suggests that for a viewer to be unaware of a cut the continuity editing rules must ensure that the visual information does not change in a way that is significant to the viewer’s current attentional set or that insufficient attention is available for awareness. Suggestions of how the continuity editing rules could manipulate these factors will be presented in Chapter 3:.

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In document An attentional theory of continuity editing (Page 40-44)