Gilbert's Behavior Engineering Model (BEM)

In 1978, Thomas Gilbert published Human Competence: Engineering Worthy Performance which described the Behavior Engineering Model (BEM) for performance analysis. This model consists of three Leisurely Theorems that:

  1. distinguish between accomplishment and behavior to define "worthy performance",
  2. identify methods for determining the "potential for improving performance (PIP)" (Chyung, 2002, p.2), and
  3. describe six essential components of behavior that can be manipulated to effect performance (Gilbert, 1978, p.83).

Determine Worthy (Desired) Performance

The first step to using the BEM invloves identifying desired or "worthy" performance. This level of performance is characterized by behavior (B), or what a person does, and accomplishment (A), the outcomes of the behavior. The relationship between these factors can be expressed as:

Effective solutions must address both of these factors of performance. For example, an intervention may change an individual's behavior, but if the desired outcome or accomplishment does not result from that changed behavior, worthy performance has not been achieved. The figure below illustrates practical examples of this relationship.



Worthy Performance

Learns to use e-mail system

People do not respond to e-mail messages sent


People respond appropriately to e-maill messages


Increases number of sales calls

Sales remain the same


Sales increase



Determine the Potential for Improving Performance (PIP)

The gap between desired and current performance can be determined by comparing "the very best instance of that performance with what is typical" (Gilbert, 1988, p.49). Exemplary performance (W ex ) is demonstrated when behaviors result in the best outcomes. Typical performance (Wt) is the current level of performance. The potential for improving performance (PIP) is the the ratio between the two and can be expressed as:

The PIP is the performance gap. The greater the gap, the greater the potential for typical performers to improve their performance to the exemplary level. Rather than viewing this gap as a problem, this model helps people see the potential for improvement more positively (Chyung, 2002).

Diagnose Possible Influences on Behavior

For any given accomplishment, a deficiency in performance always has as its immediate cause a deficiency in a behavior repertory (P), or in the environment that supports the repertory (E), or in both. But its immediate cause will be found in a deficiency of the management system (M).
(Gilbert, 1978, p.76)

In order to understand what changes must be made to a management system to achieve worthy performance, a performance technologist must first determine the influences on behavior. Gilbert (1978) states that behavior is the product of the personal characteristics of an individual (repertory) and the environment where behaviors occur. Within each of these aspects of behavior there are conditions that can be examined for deficiencies and ultimately manipulated to improve performance. These six conditions of behavior, numbered according the Gilbert's suggested sequence for analysis, are outlined in the table below:






The Environment

1. Data

2. Instruments

3. Incentives

The Management System

  • Does the individual know what is expected of them?
  • Do people know how well they are performing?
  • Are people given guidance about their performance?
  • Do people have the right tools for performance?
  • Are tools and materials designed to match the human factors of performance?
  • Are adequate financial incentives that are contingent upon performance available?
  • Are nonmonetary incentives available?
  • Are career development opportunities available?

Repertory of The Individual

4. Knowledge

5. Capacity

6. Motives

  • Do people have the skills and knowledge needed to perform as expected?
  • Is well-designed training that matches requirements of performance available?
  • Is performance scheduled for times when people are at their best?
  • Do people have the aptitude and physical ability to perform the job?
  • Has a motivation assessment been performed?
  • Are people willing to work for the incentives?
  • Are people recruited to match the realities of the job?


Identifying Strategies for Performance Improvement

All six conditions of behavior are equally important and must be present for performance to occur. However, after diagnosing performance problems using the BEM, HPT practitioners should seek to influence the condition(s) that have the greatest leverage for improving performance. That is, they should determine the strategies that will provide the greatest improvement with the least cost (Gilbert, 1978).

Following the sequence of steps in the cause analysis process is most likely to uncover the variables that can be improved with the least costly intervention strategies first. Improvements to environmental conditions generally have the greatest leverage for performance improvement. Providing people with clear expectations of and feedback on performance, the right tools for the job, and appropriate rewards and recognition for performance are often the most cost effective changes that can be implemented within a management system. It is more difficult and costly to directly impact the inherent qualities of an individual. If the PIP is still large after the environmental supports of behavior have been manipulated, the performance technologist may consider an instructional intervention to improve a person's knowledge and skills. The capacity and motives for an individual's behavior are conditions that are probably best met through selection and recruitment of performers, interventions that may be less cost effective to implement once a performance gap exists.

Diffusion of Effect
Whenever I change some condition of behavior, I may indeed---and often will---have a significant effect on some other aspect of behavior...There is no way to alter one condition of behavior without having at least some effect on another aspect---often, a considerable effect.
(Gilbert, 1978, p. 94)

When considering this sequence of analysis and intervention, it is very important for the performance technologist to recognize what GIlbert calls "the diffusion of effect." This is good news for managers and performance technologists. Less costly interventions aimed at improving incentives, providing better feedback, or redesigning tools and materials may indirectly improve individuals' attitudes about work (motives) or help them to learn more of what they need without formal instructional interventions. This concept also supports the need for well designed interventions, as even the most motivated, knowledgeable, or able person cannot achieve worthy performance with ineffective tools, feedback, or incentives.

For additional information and samples of interventions, see the Performance Intervention section of the toolkit.


Chyung, Y. (2002). IPT 536: Week 4: Behavior engineering model. Lotus Notes database via Boise State University. Retrieved February 1, 2002.

Gilbert, T. (1978). The behavior engineering model. In T. Gilbert, Human competence: Engineering worthy performance (pp. 73-105). New York: McGraw-Hill.