Click for next page ( 9


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 8
8 Improving Safety-Related Rules Compliance in the Public Transportation Industry the job done on time than on its safety policies (situational violation)? In this circumstance, the organization's safety culture may be the cause. Perhaps an employee consistently chooses not to comply because he or she did not understand why the rule is required (routine violation). Closer enforcement and explanation of the rules may prevent this behavior. The following sections describe factors and countermeasures known to influence noncompliance. Perceptual Errors Perception is a psychological construct that describes the neural processes that transform sensory information that enters the brain from sensory organs (e.g., eyes, ears). Most research on perception involves vision and audition (or hearing). Perception occurs as the result of both bottom-up and top-down processes. Bottom-up processing refers to the brain's ability to com- bine simple, bottom-level features that allows humans to recognize more complex whole patterns. Bottom-level features are the individual components that make up a representation. Visually, it is the simple lines and shapes that form more complex patterns, like a face. An aural example is phonemes, or individual sounds, that make up words. Many times, however, information in our environment at the bottom-level is degraded or obscured. Through top-down-processing, in the form of expectation, the brain fills in the missing information. Top-down processing refers to the brain's ability to use a person's knowledge about how the world is organized to identify patterns (Proctor and Van Zandt 1994). Top-down processing provides humans with an efficient way to process in-coming informa- tion. If all information were processed piecemeal as it would be in a totally bottom-up system, human information processing would occur too slowly to allow humans to be able to respond to safety-critical situations, a highly adaptive feature. However, there is a disadvantage regard- ing the role of expectation with respect to safety-critical situations. A person's expectations, which are based on previous experience, can lead to error (Green 2003). A relevant example of error arising from expectation occurs in the runway environment. Pilots are often familiar with the standard taxi routes at the airports they frequently fly to. However, due to unexpected operational changes, air traffic controllers sometimes instruct pilots to tra- verse a different taxi route. There are reports that describe the scenario where pilots will hear and confirm the non-standard taxi route, but during execution, they will revert to the more familiar taxi route (DiFiore and Cardosi 2006). Often times, they report that they heard what they expected. Expectation is an important contributing factor to rules noncompliance involving safety-critical communication. Top-down processing can also be a source of human error with respect to visual perception. Obscured or degraded signage cannot be processed completely with bottom-up processing (Wickens and Hollands 2000). Therefore, the brain attempts to fill in the missing information via top-down processing. Errors can occur when the brain fills in incorrect information leading to misinterpretation. These types of errors occur in the medical industry where medication labels are often not dissimilar enough with respect to medication or dosage, sometimes resulting in fatalities (Frey et al. 2002). Distraction Vehicle control is a complex activity involving multiple tasks and multichannel information input. Because humans are inherently limited in processing complex tasks simultaneously, activ- ities or conditions that compete for the driver's attention pose a risk to the driver's control over the vehicle (Sheridan 2004). Wickens' multiple resource theory states that tasks that draw on the