Inattentional Blindness

Overview

Source: Laboratory of Jonathan Flombaum—Johns Hopkins University

We generally think that we see things pretty well if they are close by and right in front of us. But do we? We know that visual attention is a property of the human brain that controls what parts of the visual world we process, and how effectively. Limited attention means that we can't process everything at once, it turns out, even things that might be right in front of us.

In the 1960s, the renowned cognitive psychologist Ulrich Neisser began to demonstrate experimentally that people can be blind to objects that are right in front of them, literally, if attention is otherwise distracted. In the 1980s and 1990s, Arien Mack and Irvin Rock followed up on Neisser's work, developing a simple paradigm for examining how, when, and why distracted attention can make people fail to see the whole object. Their experiments, and Neisser's, did not involve people with brain damage, disease, or anything of the sort, just regular people who failed to see objects that were right in front of them. This phenomenon has been called inattentional blindness. This video will demonstrate basic procedures for investigating inattentional blindness using the methods of Mack and Rock.¹

Procedure

1. Stimuli and design

The stimuli for this experiment can be made with basic slide software such as PowerPoint or Keynote.
The first stimulus to make is called the noncritical stimulus.
1. On a white slide, create two black lines; the first should be about 80% of the vertical length of the whole slide, and the other just slightly longer. In Figure 1a, the slide is 770 px long, the shorter line is 630 px long, and the other is 645 px.
2. Now choose the shorter of the

Results

Figure 6 graphs the percent of participants who saw the critical stimulus in the critical trial of each of the three types of trial sets. Note that far fewer saw it in the inattention set, and more importantly, in that set only about 40% saw the stimulus at all. That means that 60 out of every 100 participants failed to see a large object right in front of them. This failure is what is called inattentional blindness. The length judgment task is difficult and uses up all of the observer's atten

Application and Summary

An important set of applications for inattentional blindness research is in the domain of driving safety. When people have car accidents, it is not uncommon for them to report that they failed to see the car, or person, or object that they hit. It makes sense to think they failed to see it because they were perhaps looking away. Inattentional blindness suggests that they could fail to see even while looking in the right place, that is, if attention is distracted. Researchers

References

Rock, I., Linnet, C. M., Grant, P.I., and Mack, A. (1992). Perception without Attention: Results of a new method. Cognitive Psychology 24 (4): 502-534.