Poka Yoke

IEEE TRANSACTIONS ON REHABILITATION ENGINEERING, VOL. 6, NO. 3, SEPTEMBER 1998

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Impact of a Poka-Yoke Device on Job Performance of Individuals with Cognitive Impairments
Robert F. Erlandson, Michael J. Noblett, and Judith A. Phelps
Abstract—Job performance and production related issues are important not only to successful vocational training and ultimate job placement for individualswith cognitive disabilities, but also for their ability to have expanded vocational options. This study hypothesized that the application of Kaizen philosophy, and pokayoke techniques in particular, could create job opportunities and improve productivity of individuals with cognitive disabilities. Poka-yoke or error-proofing techniques are part of the collection of Kaizen techniques. Kaizen refersto continuous improvement in performance, cost/effectiveness, and quality. Kaizen strives to empower the worker, increase worker satisfaction, facilitate a sense of accomplishment, and thereby create pride-of-work. These techniques typically reduce the physical and cognitive demands of a task and thereby render the task more accessible. The job was a fuel clamp assembly. A redesigned assemblyfixture was the poka-yoke intervention. Consistent with pokayoke principles, the intervention improved the productivity of everyone attempting the assembly. In particular, the workers in this study showed an 80% increase in productivity and an average percent error drop from 52% to about 1% after the process redesign. Furthermore, the workers showed improved morale, self-esteem, and pride-of-work. Priorto the process redesign, only the higher functioning workers could successfully perform the assembly. After the redesign a greater number of workers could successfully perform the assembly. These results not only validated the study hypothesis, but demonstrated that the success facilitated by applying Kaizen techniques had similar results with individuals with cognitive disabilities as withnondisabled workers.

I. INTRODUCTION HE ability to do the essential functions of a job, unaided or with reasonable accommodations, is a key issue with respect to competitive employment of individuals with cognitive disabilities. For assembly and packaging jobs, essential functions involve working at specified assembly rates, production rates, or acceptable error rates. Job performance and productionrelated issues are important not only to the successful vocational training and ultimate job placement for individuals with cognitive disabilities, but also for their ability to have expanded vocational options. The importance of production for individuals with disabilities is often under estimated because it is not an isolated factor, but rather is associated with psychological and social factors.Manuscript received December 8, 1995; revised September 25, 1997 and May 15, 1998. R. F. Erlandson is with the Enabling Technologies Laboratory, Electrical and Computer Engineering, Wayne State University, Detroit, MI 48202 USA. M. J. Noblett is with the Engineering Group Manager, Cadillac Luxury Car Division, General Motors Corporation, Flint, MI USA. J. A. Phelps is with the AssistiveTechnology Resource Center, Wayne County Regional Educational Service Agency, Allen Park, MI 48101 USA. Publisher Item Identifier S 1063-6528(98)05921-7.

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Studies by Greenspan and Shoultz [1] and Hanley-Maxwell, Rusch et al. [2] found that persons with disabilities most often lost their jobs for social reasons. The Hanley-Maxwell et al. study [2] examined factors reported to contribute to jobtermination of adults with disabilities. There were 51 subjects and 103 reasons given. Statistical analyzes showed that the distribution of reasons was not random. The single most frequent cause for job termination was production, closely followed by character. These results seem contradictory until the multifaceted nature of the problem is revealed. The HanleyMaxwell et al. study [2] showed that a...