40 Principles with Examples: Human Factors & Ergonomics

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    By Stan Caplan, Michael Tschirhart and Jack Hipple


    Over the past ten years, there have been several 40 inventive principles lists with examples that illustrate the breadth of Genrich Altshuller's work; the founder of The Theory of Inventive Problem Solving (TRIZ).1,2,3

    The 40 principles framework has shown its robustness in its ability to capture key inventive examples across many different technologies and businesses. Though the TRIZ methodology has advanced beyond this simple characterization, these principles along with the original contradictions table both still remain as legitimate problem solving tools. Both tools offer a way to get problem owners to think in terms of overcoming contradictions as opposed to compromising and optimizing. After this basic understanding, they can move on to more sophisticated TRIZ tools and algorithms.

    Human factors and ergonomics are the sciences relating to the relationship among humans and their working environments, including:

    This entire area has become a major area of focus as the population ages and the elderly still need to drive cars, interact with machinery (even as small as a can opener) and see and interpret information on signs. Tasks that are taken for granted such as boarding an airplane or reading a speedometer in a car are not as easy for an elderly person or one with physical limitations such as arthritis. There is a classical contradiction with providing an over-the-counter medicine bottle that is easy to open for an elderly arthritic while at the same time preventing access to the same bottle with a young child that could easily open it.


    The authors have developed a list of examples for the 40 principles applied to the area of human factors and ergonomics. This is the area of science and engineering that relates to the relationships among humans and their working environments, including human-machine interfaces. With the arrival of several interfaces in multiple industries, this has become a major engineering challenge. As the population ages, the ability of individuals to access and use devices and systems is compromised by their physical abilities. Many designed systems are not suitable for all people. When a system is designed for one population, it may not be easily used by others. For example, a sophisticated display screen on a state of the art copier may be appropriate for a professional office assistant, but a manager walking by and wanting to make a few black and white copies is overwhelmed by the complexity of the copier. If the screen's display were to change based on the user, then a TRIZ separation principle has been used to resolve the contradiction of the display needing to be simple and uncomplicated. Another example is remote controls for televisions and other electronic devices. The tendency is to design complicated interfaces that can do everything when what is really needed is an interface that is appropriate for the use at that time only for the user.

    In workplace ergonomics, there is a need to learn how to pre-position workplace materials in such a way as to minimize bodily stress in reaching for assembly components (a "do it in advance" TRIZ principle). Designs that minimize the potential negative impact on the worker while increasing productivity demonstrates the time honored TRIZ approach of resolving contradictions rather than finding some kind of optimum condition.

    The following includes TRIZ principles for human factors and ergonomics with an area of science and engineering that relates to the relationships among humans and their working environments, including human-machine interfaces.

    Principle 1: Segmentation

    A. Divide an object into independent parts.

    B. Make an object easy to disassemble.

    C. Increase the degree of fragmentation or segmentation.

    Principle 2: Taking Out

    A. Separate an interfering part or property from an object or single out the only necessary part (or property) of an object.

    Principle 3: Local Quality

    A. Change an object's structure from uniform to non-uniform, change an external environment (or external influence) from uniform to non-uniform.

    B. Make each part of an object function in conditions most suitable for its operation.

    C. Make each part of an object fulfill a different and useful function.

    Principle 4: Asymmetry

    A. Change the shape of an object from symmetrical to asymmetrical.

    B. If an object is asymmetrical, increase its degree of asymmetry.

    Principle 5: Merging

    A. Bring closer together (or merge) identical or similar objects, assemble identical or similar parts to perform parallel operations.

    B. Make operations contiguous or parallel; bring them together in time.

    Principle 6: Universality

    A. Make a part or object perform multiple functions; eliminate the need for other parts.

    Principle 7: Nested Doll

    A. Place one object inside another; in turn, place each object inside the other.

    B. Make one part pass through a cavity in the other.

    Principle 8: Anti-weight

    A. To compensate for the weight of an object, merge it with other objects that provide lift.

    B. To compensate for the weight of an object, make it interact with the environment (use aerodynamic, hydrodynamic, buoyancy and other forces).

    Principle 9: Preliminary Anti-action

    A. If necessary to do an action with both harmful and useful effects, this action should be replaced with anti-actions to control harmful effects.

    B. Create beforehand stresses in an object that will oppose known and undesirable working stresses later on.

    Principle 10: Preliminary Action

    A. Perform (before it is needed) the required change of an object (either fully or partially).

    B. Pre-arrange objects such that they can come into action from the most convenient place and without losing time for their delivery.

    Principle 11: Beforehand Cushioning

    A. Prepare emergency means beforehand to compensate for the relatively low reliability of an object.

    Principle 12: Equipotentiality

    A. In a potential field, limit position changes (such as a change in operating conditions to eliminate the need to raise or lower objects in a gravity field).

    Principle 13: The Other Way Around

    A. Invert the action(s) used to solve the problem (instead of cooling an object, heat it).

    B. Make movable parts (or the external environment) fixed and fixed parts movable).

    C. Turn the object (or process) upside down.

    Principle 14: Spheroidality – Curvature

    A. Instead of using rectilinear parts, surfaces or forms, use curvilinear ones; move from flat surfaces to spherical ones; from parts shaped as a cube (parallelepiped) to ball-shaped structures.

    B. Use rollers, balls, spirals, domes.

    C. Go from linear to rotary motion. Use centrifugal forces.

    Principle 15: Dynamics

    A. Allow (or design) the characteristics of an object, external environment or process to change to be optimal or to find an optimal operating condition.

    B. Divide an object into parts capable of movement relative to each other.

    C. If an object (or process) is rigid or inflexible, make it movable or adaptive.

    Principle 16: Partial or Excessive Actions

    A. If 100 percent of an object is hard to achieve by using a given solution method then, use slightly less or slightly more of the same method. The problem may be considerably easier to solve.

    Principle 17: Another Dimension

    A. To move an object in a two- or three-dimensional space.

    B. Use a multi-story arrangement of objects instead of a single-story arrangement.

    C. Tilt or re-orient the object, lay it on its side.

    D. Use another side of a given area.

    Principle 18: Mechanical Vibration

    A. Cause an object to oscillate or vibrate.

    B. Increase its frequency (even up to the ultrasonic).

    C. Use an object's resonant frequency.

    D. Use piezoelectric vibrators instead of mechanical ones.

    E. Use combined ultrasonic and electromagnetic field oscillations.

    Principle 19: Periodic Action

    A. Instead of continuous action, use periodic or pulsating actions.

    B. If an action is already periodic, change the periodic magnitude or frequency.

    C. Use pauses between impulses to perform a different action.

    Principle 20: Continuity of Useful Action

    A. Carry on work continuously; make all parts of an object work at full load, all the time.

    B. Eliminate all idle or intermittent actions or work.

    Principle 21: Skipping

    A. Conduct a process or a certain stage (destructible, harmful or hazardous operations) at high speed.

    Principle 22: "Blessing in Disguise" or "Turn Lemons into Lemonade"

    A. Use harmful factors (particularly, harmful effects of the environment or surroundings) to achieve a positive effect.

    B. Eliminate the primary harmful action by adding it to another harmful action to resolve the problem.

    Principle 23: Feedback

    A. Introduce feedback (referring back, cross-checking) to improve a process or action.

    B. If feedback is already used, change its magnitude or influence.

    Principle 24: Intermediary

    A. Use an intermediary carrier article or intermediary process.

    B. Merge one object temporarily with another (which can be easily removed).

    Principle 25: Self-service

    A. Make an object self-serve by performing auxiliary helpful functions.

    B. Use waste resources, energy or substances.

    Principle 26: Copying

    A. Instead of an unavailable, expensive, fragile object, use simpler and inexpensive copies.

    B. Replace an object or process with optical copies.

    C. If visible optical copies are already used, move to infrared or ultraviolet copies.

    Principle 27: Cheap Short-living Objects

    A. Replace an inexpensive object with a multiple of inexpensive objects, comprising certain qualities (such as service life).

    Principle 28: Mechanics Substitution

    A. Replace a mechanical means with a sensory (optical, acoustic, taste or smell) means.

    B. Use electric, magnetic and electromagnetic fields to interact with the object.

    C. Change from static to movable fields from unstructured fields to those having structure.

    D. Use fields in conjunction with field-activated (ferromagnetic) particles.

    Principle 29: Pneumatics and Hydraulics

    A. Use gas and liquid parts of an object instead of solid parts (inflatable, filled with liquids, air cushion, hydrostatic, hydro-reactive).

    Principle 30: Flexible Shells and Thin Films

    A. Use flexible shells and thin films instead of three dimensional structures.

    B. Isolate the object from the external environment using flexible shells and thin films.

    Principle 31: Porous Materials

    A. Make an object porous or add porous elements (inserts, coatings, etc.).

    B. If an object is already porous, use the pores to introduce useful substances or functions.

    Principle 32: Color Changes

    A. Change the color of an object or its external environment.

    B. Change the transparency of an object or its external environment.

    Principle 33: Homogeneity

    A. Make objects interact with a given object of the same material (or material with identical properties).

    Principle 34: Discarding and Recovering

    A. Make portions of an object that have fulfilled their functions go away (discard by dissolving, evaporating, etc.) or modify these directly during operation.

    B. Conversely, restore consumable parts of an object directly in operation.

    Principle 35: Parameter Changes

    A. Change an object's physical state (to a gas, liquid or solid).

    B. Change the concentration or consistency.

    C. Change the degree of flexibility.

    D. Change the temperature.

    Principle 36: Phase Transitions

    A. Use phenomena occurring during phase transitions (volume changes, loss or absorption of heat, etc.).

    Principle 37: Thermal Expansion

    A. Use thermal expansion (or contraction) of materials.

    B. If thermal expansion is used, use multiple materials with different coefficients of thermal expansion.

    Principle 38: Strong Oxidants

    A. Replace common air with oxygen-enriched air.

    B. Replace enriched air with pure oxygen.

    C. Expose air or oxygen to ionizing radiation.

    D. Use ionized oxygen.

    E. Replace ozonized (or ionized) oxygen with ozone.

    Principle 39: Inert Atmosphere

    A. Replace a normal environment with an inert one.

    B. Add neutral parts or inert additives to an object.

    Principle 40: Composite Materials

    A. Change from uniform to composite (multiple) materials.


    1. Mann, Darrell; 40 Principles (Architecture) with Examples, The TRIZ Journal, July 2001.
    2. Hipple, Jack; 40 Inventive Principles with Examples for Chemical Engineering, The TRIZ Journal, June 2005.
    3. Mann, Darrell; Domb, Ellen; 40 Inventive (Business) Principles with Examples, The TRIZ Journal, September 1999.

    About the Authors:

    Stan Caplan is President of Usability Associates, a Human Factors consulting firm that works with companies who want customers to have a superior experience when using company products. This is accomplished through user research and application of usability design and evaluation principles and methods. Caplan founded the firm in 1998 after performing Human Factors projects and managing the Human Factors function at Eastman Kodak Company for 25 years. His experience spans development of user-centered designs for hardware, embedded software and graphical user interfaces on consumer, business, commercial and medical products and systems. Contact Stan Caplan at wood27 (at) frontier.com.

    Michael Tschirhart is a Technical Fellow at Visteon Corporation where he leads Advanced Human-Machine Interface (HMI) Research and Development. Contact Michael Tschirhart at mtschirh (at) visteon.com.

    Jack Hipple is a principal with Innovation-TRIZ. He is the TRIZ instructor for AIChE/ASME and does TRIZ workshops for ASQ, PDMA and the Human Factors and Ergonomics Society. He has written TRIZ articles for The TRIZ Journal, Quality World, Mechanical Engineering, World Futures Quarterly, Creativity and Innovation Management's inaugural TRIZ issue, as well as a special three-part series on TRIZ for Chemical Engineering Progress. Contact Jack Hipple at jwhinnovator (at) eartlink.net or visit http://www.Innovation-TRIZ.com.

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