- Terminology and the Performance Field
- The Foundation
- Systems Theory
- Scientific Management
- Other Contributing Fields
- The Formation of HPT
- The Late 1950s and Early 1960s
- The Mid-1960s to the Mid-1970s
- The Mid-1970s to the Mid-1990s
- The Mid-1990s to the Present
- About the Author
- Further Reading
By Â Joe Willmore
Originally included as a chapter in the ATD Handbook for Workplace Learning Professionals, edited by Elaine Biech, 2008.
As the study and practice of human performance improvement (HPI) becomes more widespread, it is natural for those new to the field to wonder how it started and for potential clients to question if this is a recent fad or a practice based on decades of strong research and a proven track record of successful application. Consequently, a basic understanding of how human performance technology (HPT) or HPI came to be as well as recognition of some of the major contributors and developments in the field is useful in helping to address those questions.
The field of performance improvement has emerged and evolved over the past 45 years. Â It has a strong theoretical and research foundation, has borrowed from several recognized fields, has created original concepts, and continues to evolve today. Because many of the leading figures within performance were practitioners or consultants (and thus busier doing than publishing), the timeline and credit for particular achievements is sometimes a matter of perspective.
Any effort to examine the foundations and evolution of performance improvement must start with some initial warnings. First, even in talking with or reading the works of the original pathfinders and developers of HPT, perceptions differ about some aspects of the field regarding who originated a particular concept or deserves credit for a specific approach. Â A classic case that illustrates this point in a related field is the disagreement over credit regarding the development and earlyÂ application of Six Sigma (Ramias, 2005). Simply put, some of the earlier pathfinders and creators of what came to be called HPT have different perceptions of who deserves credit for what. In part this happened because so much of HPT evolved in a short timeframe and in parallel. This evolution also happened at a time when many of the critical figures in the performance arena were consultants and seeking to brand particular models or tools. Naturally, some perspectives therefore differ as to who did what first or how similar or different particular approaches may be.
Second, using publication dates to establish a timeline is deceptive regarding HPT. For starters, some of those who contributed greatly to the field were prolific writers whereas others were barely published despite being their heavy involvement as consultants or academics. Additionally, the introduction of most concepts does not correspond with the date that they were published in many instances (Rummler, 2003). Relying on publication dates (or even publication itself) to establish a history is inherently flawed when it comes to HPTâ€”there are numerous examples of concepts that were in use in workshops and presented at conferences years, or in some cases decades, before they were formally published (Rummler, 2003). There are also practitioners who are regarded by their peers as key figures in the development of HPT, such as Don Tosti and Dale Brethower, who did not author frequently in the early stages of their HPT careers when they were both contributing significant intellectual capital to the field. Consequently, the written and academic record is at best an incomplete basis for identifying major contributors and establishing credit for key HPT concepts.
Finally, this chapter should not be regarded as a detailed list of the major contributors to the performance field. As mentioned earlier, in some cases it would be very difficult to reach agreement on whom to credit for some developments or concepts. Additionally, in a field that has gone through such explosive growth and development, any attempt at such a comprehensive list would be certain to omit useful contributors. Thus, individuals are credited at various times just to illustrate the nature of their involvement or to provide a sense of how interrelated some of the evolution of HPT has been and continues to be.
Terminology and the Performance Field
Before examining the evolution of performance improvement it is important to clarify some terminology. Thomas Gilbert is generally credited with first coining the term human performance technology in reference to the body of knowledge and practice that make up this field (Gilbert, 1992). Since that time, the literature has consistently referred to HPT or human performance technology, and practitioners have often referred to themselves as human performance technologists. James and Dana Robinson helped to popularize the terms performance consultant and performance consulting in part to clarify the role of working with (or consulting with) the client (Robinson and Robinson, 1995). ATD advocates the term human performance improvement, arguing that this terminology is clearer to clients and more accurately reflects the role (consultant) that needs to be played by the practitioner. Some practitioners see little practical difference between these three terms (HPT, HPI, and performance consulting), whereas others draw significant distinctions, arguing that â€œPerformance consultants are what we are, human performance technology is what we do, and human performance improvement is what we seek.â€ For the purposes of this chapter, these terms will be usedÂ interchangeably. Regardless of oneâ€™s belief about the merits of any of these positions, such differences in linguistics do exist, they are important to many senior practitioners in this profession, and historically, the literature has referred to HPT.
Generally speaking, performance improvement can be defined as a systematic, systemic, results-based approach to helping organizations meet their goals through the work of people. An understanding of the words that make up HPI or HPT is helpful. The word human acknowledges that the focus is on how people influence the organization. Â Therefore, the focus is not on the performance of financial investments or computer functionsâ€”except to the extent that these are influenced by humans. The word performance indicates a focus on the behavior and especially the accomplishments or results that are valuable to the organization.
Technology is often perceived by most people as referring to machinery. But technology in this context refers to a system that applies techniques and science to a subject matter (Gilbert, 1992). For instance, the field of organization development (OD) refers to outdoor team building activities (such as ropes courses or white water rafting) as challenge technology. For many performance professionals, the word technology is important because it implies that HPT is more than a collection of tools and techniques but is indeed a discipline. And the word improvement refers to measurable results in human performance that benefit the organization.
The foundation for HPT was laid decades before it ever existed in name or practice. And this foundation consists of several diverse fields of study with strong research and practical background. These fields provided some of the background that led to the creation and synthesis of HPT, or they served as resources as performance became more sophisticated. Some of these fields developed concurrently with performance, and HPT work also made contributions to them (Ramias, 2005). The foundation disciplines for performance include behaviorism, systems theory, OD, instructional systems design (ISD), ergonomics and human factors, and the management sciences. Although all of these fields provided significant contributions to what became known as HPT, behavioral psychology and systems theory were the critical sources (Brethower, 2004).
Behaviorism, especially regarding the study of learning and performance, was a major contributing discipline to the field of performance. The work of B.F. Skinner and others played a key role in the work of many of early human performance technologists (although performance as a field had yet to emerge and no consensus label for it existed at this point). Applied behavior analysis and operant conditioning research helped drive some of the initial thinking that led to the development of the performance field. Several critical contributors to HPT, such as Dale Brethower, Thomas Gilbert, Joe Harless, Susan Markle, Geary Rummler, and Donald Tosti, worked with or studied under Skinner or Fred Keller. It would be practically impossible to overstate the impact that applied behavior analysis had in shaping the thinking of many HPT pathfinders (Brethower, 2004).
Systems theory involves studying various parts of an organization and identifying inter-relationships and patterns to understand how the organization functions. Systems theory takes a holistic approach to analysis, and is an essential component of HPI, partially because the performance field integrates so many disciplines. But some of the very earliest contributions to HPT came from the insights gained by using a systems approach. For instance, Rummler, with the help of Brethower and George Geis, developed the Human Performance System Model in 1964 (Rummler, 2003).
OD deals in part with understanding organizations, looking beyond just skills and knowledge, and dealing with change. For a discipline such as HPT, which recognizes that training is not the answer to all ills and that analysis requires examining more than just individual performers, OD is a natural resource. OD has served as an area of cross-fertilization for developing and continually refining the performance field. Generally speaking, the more solution-focused and less precise approach of OD and the more systematic, measurement-focused approach of HPT appear to have limited the degree to which OD has served as a building block, instead contributing pieces, tools, or concepts (Coscarelli, Rosenberg, and Hutchison, 1992).
ISD as a discipline evolved and intermingled with HPT in several ways. The systematic approach of ISD lent itself well to performance. Most of the early key pathfinders in HPT had strong roots in ISD. As ISD developed in the 1950s, the importance of task analysis grew as well as an awareness of the need to identify the outcomes of trainingâ€”both insights that would later be incorporated into HPT. Many of the critical pathfinders in HPT, such as Bob Mager, also played similar roles in the ISD field.
Management sciences can actually be interpreted as a mixture of different disciplines that all provided some insights later useful in forming HPT. Frederick Taylor wrote in 1911 about categorizing a workforce into thinkers or doers, standardized production processes, and looked closely at job design issues that helped to create scientific management. This contributed greatly to the discipline of ergonomics and human factors research. Although a psychologist, Kurt Lewin contributed greatly to the management sciences with his work on participative management and also force field analysis. Peter Druckerâ€™s insights shapedÂ how people saw the nature of organizations and provided a better understanding of the role and function of management. Douglas MacGregor developed theories of management styles and raised organizational awareness of motivational issues (Sanders and Ruggles, 2000).
Other Contributing Fields
Additionally, other fields contributed insights in various ways to either the formation of HPT or its subsequent evolution. Work in the evaluation and measurement fields has been a source of inspiration for many performance consultants. The quality field produced a range of tools that were later modified or incorporated by various HPT practitioners. Cognitive engineering and information technology (IT) have also provided insights that have been integrated into performance work. This is not an exhaustive list of the fields that have contributed in some fashion to the study and practice of performance. Â Ironically, at a time when many professionals are becoming more specialized, the job of performance consultant benefits from a multidisciplinary approach and a breadth ofÂ knowledge. HPI practitioners have pulled lessons from many disciplines in the past to grow the field and are likely to continue doing so in the future.
The Formation of HPT
Starting in the 1950s and 1960s, key HPT pathfinders were beginning to describe the emerging body of knowledge that would come to be known as HPT. The 1960s and 1970s proved to be a very fertile time for HPT, and then the discipline took on a more public face in the 1980s and 1990s. Finally, the mid-1990s to 2007 has seen the performance field continue to evolve and grow, incorporating new technologies and responding to new conditions in the world of work, such as globalization, increased speed, greater emphasis on accountability, and more.
The Late 1950s and Early 1960s
In the late 1950s and early 1960s several researchers had begun study in applied behavior analysis and focused on programmed instruction. Some of these individuals, such as Rummler, Tosti, and Brethower, began to realize that multiple factors influenced performance. Gilbert had formed his Theory of Reinforcement (TOR) at this point and a former studentâ€”Harlessâ€”was one of his associates. Rummler and Brethower were leading workshops at the University of Michiganâ€™s Center of Programmed Learning for business in which they taught performance analysis and a three-level framework (organization, process, and job/performer), which would be published 25 years later in the book Improving Performance (Rummler, 2003). It was also at about this time that Gilbert offered a workshop on what he called human performance technology (Gilbert, 1992).
The Mid-1960s to the Mid-1970s
The period from the mid-1960s to the mid-1970s was a very fertile time for the field of HPT. Many of the key innovators were crossing paths professionally and had developed much more active consulting practices. Concepts and tools that had been developed earlier were now being implemented and revised rapidly in the consulting world. The emergence of HPT was not orderly. Much of the work during this period involved intense competition among key pathfinders seeking to brand particular tools and concepts before the competition was able to do so (Rummler, 2003). Gilbert and Rummler had formed Praxis Corporation with Irving Goldberg in 1969. Praxis formalized its Performance Audit methodology, which used Gilbertâ€™s now famous Worth concept. Magerâ€™s book Analyzing Performance Problems was published in 1970. And in 1972, Gilbert began work on the HPT book that would later be published in 1978: Human Competence.
By this point, a synthesis from other fields as well as original insight from a key group of players had produced a definable body of knowledge. It had a nameâ€”human performance technology. Despite several competing consulting firmsâ€™ claims to unique approaches to the work, there were enough shared elements to identify common HPT principles. These principles included a strong focus on results and a recognition that many factors contributed to performanceâ€”not just knowledge and skills. The concept of measuring performance by using accomplishments rather than behavior and the importance of focusing on closing performance gaps had also been identified as key principles of the discipline. Whether it was Magerâ€™s analysis of performance problems, Praxisâ€™s performance audit, or Harlessâ€™ front-end analysis (which all shared some similarities), systemic and systematic analytical approaches had been developed and were being used within organizations (Rummler, 2003). A growing body of case studies and publications documented the work being done and allowed more efficient sharing of knowledge among practitioners. Â Since HPT was formed, there was always a heavy emphasis on analytical and diagnosticÂ tools and systems (Coscarelli, Rosenberg, and Hutchinson, 1992). This period saw a series of approaches developed (Rummler, 2003), but it is also fair to say that an ongoing theme in future years for HPT would be the continual development and refinement of analytical tools and approaches as practitioners sought better ways to do this work. Â By the early to mid-1970s, HPT had a robust body of knowledge with a definable and distinct field of practice, depth in concepts and models, many successful case studies, and some visible practitioners with outstanding reputations. Although many deserve credit for the formation, initial use, and then branding of HPT, several individuals truly deserve the reputation as pathfinders for this discipline, including Brethower, Gilbert, Harless, Mager, Rummler, and Tosti.
The Mid-1970s to the Mid-1990s
From the mid-1970s to the mid-1990s, the field of HPT began a more public evolution. More specifically, the previous decade had seen a frantic and competitive development of models, concepts, and tools driven by client demands. Very little of this work was research driven and many important elements of this discipline were not publicly accessible because they resided in the heads of consultants or clients or perhaps at workshops and conferences (Rummler, 2003). In 1975, Harless was interviewed by Training magazine and talked about front-end analysis. Although he had used the term before, this interview helped to increase the exposure and awareness of the concept as well as brand his approach. Gilbertâ€™s 1978 book Human Competence proved to be a landmark publication for the field because it shared his insights about HPT and captured many of the key concepts and approaches that consultants (especially those at Praxis) had been using. It also was a platform for Gilbert to discuss his Behavior Engineering Model, which became a standard in the field and has been used by many others as a starting point in developing tools for understanding performance variables (Chevalier, 2003).
Two other books published during this period were also significant for performance. The 1990 Rummler-Brache book Improving Performance covered concepts and models that in some cases had been developed as much as 25 years earlier, making Rummlerâ€™s work much more accessible. The idea that performance analysis required a systems perspective and that potential solutions needed an integrated approach was consistent with decades of Rummlerâ€™s work, but the book served to clarify key points about systems theory and HPT that are now commonly accepted principles in the field (Rummler, 2003). Â In 1995, the Robinsonsâ€™ book Performance Consulting was published. This book introduced performance to an entirely new audience, thus raising the visibility of HPT. The Robinsonsâ€™ model emphasized the role of client engagement. This book also helped to popularize the term performance consultant, which many people found preferable to human performance technologist.
Collectively, these three books and the Harless interview increased the exposure and accessibility of HPT and provided branding or labels that made it easier or more attractive for the next generation of potential performance professionals. For a discipline in which so many of the key figures had been busy doing rather than writing, these publications (all of which provided strong exposure for the field) allowed critical concepts to be captured. They also expanded the visibility of the discipline. These were by no means the only HPT-related publications during this timeframe but these four in particular provided a unique role in publicizing the discipline, clarifying what it was, and making it accessible to new entrants.
This timeframe was also a period of significant refinement of HPT. A new generation of performance consultants entered the field and began to make their contributions either through work, research, or publication. In some cases the contributions involved new models or tools; in other cases they involved refinement of previously existing approaches. In still other instances contributions involved clarifying or reemphasizing principles from HPTâ€™s early days in ways that made those principles more preeminent. From 1960 to the mid-1970s, formal research in the field had suffered, but now HPT began to benefit from dedicated research, documentation of results, and more formalized sharing of information (Stolovitch, 2000).
New tools, concepts, and approaches were added or existing ones were clarified or sophisticated. For instance, variations of Gilbertâ€™s Behavior Engineering Model were proliferating (Chevalier, 2003). Rummler and Panza added Organizational Maps (Rummler, 2003). Mary Broad and the Robinsons helped build the case for partnering as a critical stage in HPT work. Jim Fuller, Roger Kauffman, and others emphasized the need to both understand the business and focus on organizational goals to drive HPT projects rather than just existing performance gaps. Â Although many of his publications came after this period, Tosti was making important contributions about feedback, culture, and performance.
New insights into evaluation were occurring with work by Robert Brinkerhoff, Jack Zigon, and Jack Phillips leading the way. The range of possible projects available to performance consultants continued to expand. Harless and then Allison Rossett both improved the understanding of the value and use of job aids. Action learning, coaching, large group solutions, electronic performance support systems (EPSS), and much of the work led by Sivasailam Thiagarajan around games are examples of just some of the possible solutions that either emerged in this era or were further refined.
Although both Gilbert and Harless had emphasized the role of the exemplar, this period also saw a greater awareness of the original wisdom of identifying key performers with work by Paul Elliott and others, which helped to further systematize this approach.
Finally, as the role of IT and computing exploded within organizations and society, HPT acquired tools for both analyzing the impact of IT and also tapping it for solutions. Gloria Gery was one of the leaders in this area with her work involving EPSS. Distance learning was also an area of innovationâ€”programmed instruction had been one of the precursor fields to HPT and many of those original insights gave birth to new applications.
Up to this point, the discipline was known as HPT. The publication of Performance Consulting led to many practitioners labeling themselves performance consultants.
Additionally, ATD concluded that the term human performance improvement was clearer to potential clients and began referring to the discipline in this manner.
The Mid-1990s to the Present
The mid-1990s to 2007 has seen the performance field continue to evolve and grow. The roles and competencies of a performance consultant became clearer as William Rothwell and othersâ€™ work was published in this area (Rothwell, 1999) and included movement from behavior-based competencies to outcome-based competencies. The International Society for Performance Improvement (ISPI) began to certify performance professionals with the Certified Performance Technologist (CPT) designation, and ATD later offered the Certified Professional in Learning and Performance (CPLP) certification. The result of this work (clarifying competencies, providing certification) serves to further professionalize the performance field.
From the beginning, systems theory has played a significant role in understanding performance and there have been continual insights in this area as HPI has evolved. Harlessâ€™s approach to analysis has been refined since the 1990s to reflect a less linear approach. Â Klaus Wittkuhn and others continued to rethink the understanding of cause analysis with performanceâ€”especially from a systemâ€™s perspective (Wittkuhn, 2004). Although research into HPI that both validates elements of the discipline and expands the field continues to grow, there is a need for additional work to build credibility in a field that is focused on results (Huglin, Johnsen, and Marker, 2007).
Technology has played a role in how HPI has evolved. It continues to lead to newÂ insights about performance support (Rossett, 2007). Performance diagnostic models and tools have been converted to software such as the Performance DNA Desktop, set of electronic toolsâ€”guides, checklists, and templatesâ€”to conduct a comprehensive analy- sis of human performance. The prevalence of matrix or virtual work settings has created new challenges for performance consultants. PDAs, wikis, blogs, websites, and miniaturized technology have revolutionized the job aid, information, and communication options available to the HPI field.
Outreach and education have accelerated within performance. Starting with Rossettâ€™s graduate level course in 1992, several schools now offer graduate degrees in performance improvement. Online HPI degree credit courses and a degree are possible. Both ISPI and ATD offer extensive training in the principles and tools of performance work at levels that werenâ€™t available 15 years ago. For instance, more than 11,000 individuals worldwide have taken one of ATDâ€™s HPI certificate courses. As a result of this expansion in performance resources, acquiring skills in HPI is much easier now, and the numbers of performance consultants continue to grow.
Author Daniel Gibson (2000) once said â€œthe future is already here, itâ€™s just unevenly distributed.â€ There are several organizational developments that have significant implications for HPI. Some of these developments have been present for decades but all of them have become more relevant to HPI since the mid-1990s. There is much more pressure for fast results from clients. This has always been an issue to some extent, and Rossett was one of those who acknowledged this with her book First Things Fast(1998). But the competitive pressures and faster business cycles have resulted in clients who are demanding even quicker performance analysis (Willmore, 2004). As a result, HPI is looking for ways to remain rigorous, systemic, true to its principles, yet able to speed up the analysis.
Another trend that has major implications for performance consultants is the growing emphasis on accountability. Executives are increasingly being held accountable for producing results, and this accountability is spilling down throughout the organization. Â Although this is another trend that has been happening for decades, it has accelerated since the mid-1990s. It has significant implications for HPI because this creates an organizational climate in which performance consulting has more perceived value by potential clients. HPI has also begun to migrate in some instances from human resources to other departments in the organization (such as operations), or internal performance consultants are co-located to be close to their internal clients.
Since 2000, there has been a significant interest in the practice of Six Sigma. Ironically, Rummler helped provide much of the insight to Motorola where Six Sigma evolved (Ramias, 2005). In a very short time Six Sigma has gained tremendous visibility and executive support, sometimes at the expense of HPI. So two questions for the future will be how effectively performance consultants can both explain to clients why Six Sigma is not a competitor with HPI and also effectively partner with Black Belts to further organizational goals.
Additionally, the nature of work is changing, which also has implications for HPI.
More work is being automated and some have argued that this potentially results in less value that performance consultants can provide organizations (Nickols, 2003). Others, however, take the position that the jobs that remain require more decision making or dis- cretion and therefore are more variable in terms of how the work can be done correctly (Pepitone, 2000). Because HPI focuses first on the results rather than the behavior, performance consultants should become more valuable as older models that rely on evaluating employees through behavior become less relevant.
Finally, the nature of the workforce and competition is changing. Most markets are truly global. Many workforces (certainly in North America and Western Europe and in many other regions as well) are much more diverse and multicultural. This has had a significant effect on HPI in that the discipline has become more internationalâ€”there are now many more performance consultants outside of North America. This may create cultural challenges to some elements of the performance analysis approach, such as a need to couch the performance gap in terms of a different concept. For the performance consultant, the presence of a less homogenous workforce with different languages and cultures has always been an organizational challenge but it is much more prevalent today. Combine this with global markets where businesses work across hemispheres and with differentÂ cultures, and it is obvious that organizations will face new challenges as they compete internationally. As a result, performance consultants will face more performance issues that are fully or partially a function of challenges presented by a balkanized workforce and multiple markets.
HPI has grown significantly since the formation of the performance field in the earlyÂ 1960s. One sign of a vibrant and healthy discipline is the ability to tap into new developments, innovate, and also capture insights from other fields. HPI continues to do exactly that. The last decade has seen a tremendous expansion of potential performance consultants as well as new ways in which the performance field has evolved.
The author would like to give special thanks to Geary Rummler and Don Tosti for their assistance in preparing this chapter.
About the Author
Joe Willmore is president of the Willmore Consulting Group, a performance consulting firm located in Northern Virginia in the United States. He is a former member of ATDâ€™s board of directors and the author of Managing Virtual Teams, Performance Basics, Job Aid Basics, and No Magic Bullet. He was also a facilitator for ATDâ€™s HPI program. He has consulted for a range of clients around the world for the past three decades.
Brethower, Dale. 2004, September. Yes, We Can, available at www.ispi.org/services/Glossary /YesWeCan.pdf
Chevalier, Roger. 2003, May/June. Updating the Behavior Engineering Model. Performance Improvement, 8-14.
Coscarelli, C., Marc Rosenberg, and C. Hutchison. [Author: provide first names.] 1992. The Origins and Evolution of the Field. In Handbook of Human Performance Technology. Eds. Erica J. Keeps and Harold D. Stolovitch. San Francisco: Jossey-Bass.
Gibson, William. 2000. Â The Economist, June 23.
Gilbert, Thomas 1992. Foreword. In Handbook of Human Performance Technology. Eds. Erica J. Keeps and Harold D. Stolovitch. San Francisco: Jossey-Bass.
Huglin, L., L. Johnsen, and A. Marker. 2007, 1st quarter. Research Priorities in Performance Technology. Performance Improvement Quarterly, 79-96.
An Interview with Joe Harless. 1975, March. Training, 43-45.
Nickols, Fred. 2003. Human Performance Technology: The End of an Era, available atÂ http://home.att.net/~OPSINC/end_of_era.pdf
Pepitone, James. 2000. Human Performance Consulting. 1st ed. Houston, TX: Gulf Publishing.
Ramias, A. 2005, October. The Mists of Six Sigma, available at www.bptrends.com/publication-files/10-05%20WP%20The%20Mists%20of%20Six%20Sigma%20-%20Ramas1.pdf
Robinson, Dana, and James Robinson. 1995. Performance consulting. 1st ed. San Francisco: Berrett-Koehler.
Rossett, Allison. 1998. First Things Fast: A Handbook for Performance Analysis. San Francisco: Jossey-Bass=Pfeiffer.
Rossett, Allison. 2007. Performance Support Yesterday and Today, available atÂ http://it.coe.uga.edu/itforum/paper99/ITForum_rossett.pdf
Rothwell, William J. 1996. ATD Models for Human Performance Improvement. Alexandria, VA: ATD Press.
Sanders, Ethan S., and Julie L. Ruggles. 2000, January. HPI soup. Training & Development, 27-36.
Rummler, Geary. 2003, August. The Perils of Writing and Reading Histories of HPT, available at www.performancedesignlab.com
Rummler, Geary, and Alan Brache. 1990. Improving Performance: How to Manage the White Space on the Organization Chart. San Francisco: Jossey-Bass.
Stolovitch, Harold D. 2000, April. HPT: Research and theory to practice. PerformanceÂ Improvement, 7-25.
Willmore, Joe. 2004, August. The Future of Performance. T+D, 26-31.
Wittkuhn, Klaus. 2004, March. Systems, Nontrivial Machines, Circular Causality and Other Ghosts Haunting HPT. Performance improvement, 33-38.
Dean, Peter, and David Ripley. 1997. Performance improvement pathfinders. Washington, D.C.: ISPI Press.
Elliott, Paul, Elena Galbraith, and Al Folsom. 2005, June. Making the exemplary normal. T+D, 41- 51.
Gilbert, Thomas, 1978. Human competence: Engineering worthy performance. Washington, D.C.: ISPI Press.
Harless, Joseph. 1989, May. Wasted behavior: A confession. Training, 35-38.
Rummler, Geary. 2004, April. Readerâ€™s forum. Performance improvement, 5.