Have you ever been so engrossed in your work that you didn't even see someone had come into your office? Intently reading from the computer monitor, you are startled when the visitor finally speaks. This might be an example of inattentional blindness: a failure to perceive an unexpected object because attention is diverted to another object or task (Most, et al, 2000; Simons & Chabris, 1999; Mack & Rock, 1998). In one infamous experiment, observers did not notice a gorilla because they were busy keeping track of how many times a basketball was passed back and forth (Simons & Chabris, 1999).

A related phenomenon is change blindness: a failure to notice changes to objects or scenes, especially if the objects are not of interest in the scene (Rensick, 2004; Levin, et al, 2002; Rensink, et al, 1997). For example, we may not notice changes on the drive to work, because we have become numb to the route and the changes are not large enough to notice.

Both of these types of cognitive blindness are not very good phenomenon when trying to deliver quality software. Cem Kaner suggested inattentional blindness might affect the process of finding software bugs, especially since testers are asked to find mistakes that coders did not find (2004).

Next post, I will investigate how cognitive blindness affects software teams.

Sources
Kaner, C. (2004). Software testing as a social science. IFIP Working Group 10.4 meeting on Software Dependability, Siena, Italy, July 6, 2004. Retreived from http://www.testingeducation.org/a/ifipkaner.pdf on Oct 13, 2004.

Levin, D. T., Simons, D. J., Angelone, B. L., & Chabris, C. F. (2002). Memory for centrally attended changing objects in an incidental real-world change detection paradigm. British Journal of Psychology, 93, 289-302.

Mack, A. & Rock, I. (1998). Inattentional Blindness. Cambridge, MA: MIT Press.

Most, S. B., Simons, D. J., School, B. J., & Chabris, C. F. (2000). Sustained inattentional blindness: The role of location in the detection of unexpected dynamic events. Psyche, 6(14).

Rensink R. A. (2004). Visual sensing without seeing. Psychological Science, 15, 27-32.

Rensink, R. A. (2002). Change Detection. Annual Review of Psychology, 53, 245-277.

Rensink R. A., O'Regan J. K., and Clark J. J. (1997). To see or not to see: The need for attention to perceive changes in scenes. Psychological Science, 8, 368-373.

Simons, D. J. & Chabris, C. F. (1999). Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception, 28, 1059-1074.

Simons, D. J., Chabris, C. F., Schnur, T. (2002). Evidence for preserved representations in change blindness. Consciousness and cognition, 11, 78-97.