The Cognitive Principles of Gerhardt-Powals: Ace your capacity to understand human behavior!

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Even if we do not realize it, we live in our own “bubbles”. We easily forget that the world is not the same for everyone, and this is why human-centered design is so important. As user experience designers, we need to fight to forget our own bubble and understand those of our target users. The cognitive principles of Gerhardt-Powals are yet another way of doing so.

Why bring in a new set of heuristics? You might not even run heuristic evaluations yourself. The truth is that you do not need to in order to find value in the cognitive principles of the Gerhardt-Powals heuristics. We invite you to look at these principles from another point of view. Let’s consider them tools for you to become even more knowledgeable on human behavior.

As designers, we see the world from a different point of view. This tendency to observe as designers rather than as administrators, veterinarians, salespeople, etc. is peculiar to professions of all types. There is a cognitive bias with a French name —déformation professionnelle—that tidily captures this trait. This “professional deformation” or “professional distortion” is a natural result of working in a career. Have you ever heard anyone ask you to explain something “in layman’s terms”? When you see a side of the world that the general population doesn’t have much contact with, it’s a privileged position to have. The only trouble with that is that it can angle your point of view or blind you in some aspects. Therefore, also as designers, we see the world with a specific set of glasses.


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Just to give you a few examples, in 2008, the Institute for Dynamic Educational Advancement (IDEA) ran a study called “Finding Information: Factors that improve online experience”. The surveys were analyzed to explore and compare the factors that drive online experience as expressed by the three different subject groups – nonprofit organizations and cities, web designers and firms, and the general public. Here are some key differences between designers and users:

  • Designers underestimate the thresholds for an effective site. As a result, designers should give greater consideration to overall effectiveness, thereby reducing the chance of failure for a user to find the information he/she seeks.
  • Designers are overly optimistic about visitors’ ability to maintain orientation. “Your visitors don’t know your site as well as you do, so make sure it is obvious how to find information through meaningful menus, prompts, and not too much clutter.”
  • Visitors still need handholding. Based on survey feedback, around 70% of the organizations and web visitors thought that a personal guide would be helpful in making the site more effective. However, only 50% of designers thought so.
  • Thus, it is very easy for us – as designers – to live in our “bubble” and assume that we see the world as anyone else does. If you’ve ever heard the expression, “it’s not rocket science”, you may think of an aloof scientist in a laboratory, speaking in equations to his assistants. That’s the sort of false sense of security we need to overcome as designers; we can fall into that trap, too.

Using the cognitive principles as a reality check

While nothing can substitute the contact with real end users, you can equip yourself with tools that help you to run “reality checks”. Working on empathy is a perfect way. Learning how people are and keeping that always in mind is another.

The Gerhardt-Powals cognitive principles

Jill Gerhardt-Powals – a professor from the Information and Computer Science Program at Stockton University – developed a set of cognitive principles for enhancing computer performance. These heuristics or principles are similar to the Nielsen and Molich rules of thumb but take a more holistic approach to evaluation. They are:

1. Automate unwanted workload.

  • Free cognitive resources for high-level tasks.
  • Eliminate mental calculations, estimations, comparisons, and unnecessary thinking.

As designers, we know all about not giving our users work to do. Do you remember Gestalt Laws? By using such principles as continuity or proximity, we can make it easy for the user’s eye to “think” for the brain. There are several ways of designing so that users find themselves not having to ask your design questions, and they can have fun in the process as they look at cool effects.

2. Reduce uncertainty.

  • Display data in a manner that is clear and obvious.

This means designing the data to appear in the briefest and simplest manner possible. Keeping Hick’s Law firmly in mind here will pay big dividends: that is, the more choices you present your users with, the longer it will take them to reach a decision. A user who’s following a direct and straightforward “pathway” with certainty is more likely to follow through with what you want him/her to do.

3. Fuse data.

  • Reduce cognitive load by bringing together lower level data into a higher-level summation.

Here, it’s important to consolidate the small bits of data in an all-encompassing description. Your users have memory loads; giving them a “running commentary” string of individual pieces of data can tax them and try their patience. If you can combine a string of facts into a summary statement, you’ll save them from getting frustrated. Don’t feel like you’re patronizing them because you connected the “dots” for them.

4. Present new information with meaningful aids to interpretation.

  • Use a familiar framework, making it easier to absorb.
  • Use everyday terms, metaphors, etc.

We should never underestimate the value of a relevant analogy. If you’ve got an abstract concept and a metaphor fits, use it. The computing world has applied metaphors before: a “Trojan” virus comes from the mythical wooden horse the Greeks used to attack the defenders of Troy. Carl Sagan was an expert at metaphor use, presenting lofty concepts in a language any television viewer of his “Cosmos” series (1970s) could understand. For example, by slicing an apple pie, he introduced slicing atoms.

5. Use names that are conceptually related to function.

  • Context-dependent
  • Attempt to improve recall and recognition.
  • Group data in consistently meaningful ways to decrease search time.

Remember that if a user has to take a moment to remember something, a) that is work, and b) that user might not be able to remember easily, which will frustrate him/her and weaken the impact of your design. Recognition is far more powerful a tool than recall. If we use a little metaphor here, we can see this illustrated. If we treat our web design like we’re showing users a map, it’s far better to ease the process by narrowing down the possibilities so that they don’t make “wrong turns”. If you want the user to “click”, use “click” consistently, as you would expect to see post offices or rivers marked on a map in a consistent way. Lay out your elements so that the user recognizes them or intuits use right away. Remember your Gestalt Laws and apply them appropriately. That way, you will have done their searching and sorting for them before they’ve even had to think about it.

6. Limit data-driven tasks.

  • Reduce the time spent assimilating raw data.
  • Make appropriate use of color and graphics.

Here again, we can aim to design in such a way that our users can focus on graphic display. In web design, we have a powerful arsenal, or toolbox, at our disposal. We can present raw data in ways that won’t bog down the user’s attention. The Gestalt Laws again come to our aid. We can draw the user’s eye to any desired element as if it were a bulls-eye on a dart board. Knowing the appropriate color schemes is a big help there. Consider contrast, for example.

7. Include in the displays only that information needed by the user at a given time.

Guiding the user one step at a time means providing the relevant information in small releases. Instruction manuals adopt this step process and for good reason. The more sophisticated your web design, the more “chapters” of information you will have to create. Avoid the temptation to combine steps; if you need an extra link or page, it’s far better to do that than risk crushing the text. Whitespace is a great calming tool.

8. Provide multiple coding of data when appropriate.

Can you show your data in several ways or at several levels? Not all users like bar charts or graphs, for example. Think laterally: is there another means by which you can represent your detail in order to satisfy users of all types? What about their ability levels? Is your web design accessible by everyone in at least one way at any given moment?

9. Practice judicious redundancy.

Carefully applied redundancy of information is important to ensure that you leave nothing “out”. As we’re using the word “judicious”, let’s think of a courtroom. Lawyers practice the art of questioning so that a witness can confirm statements of fact. As a designer, you can use this sensible redundancy by giving repeated information than the user would otherwise need. This keeps consistency and prevents confusion or ambiguity. This step is particularly good for catching any conflicts that arise between numbers 6 and 8 on our list.

A little bit on heuristic evaluation


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While heuristics and cognitive principles – as we have just seen – are valuable tools per se, let’s us do some refreshing on heuristic evaluation!

Heuristic evaluation is an inspection method that has both followers and detractors. The problem often comes when it is used as a substitute for user testing. Inspection methods should not be the alternative of going out and really understanding our target users. To know the difficulties that our users truly encounter with our designs and to see how to fine-tune them, there is no other way than to test our prototypes with them.

Jeff Sauro, the founding principal of MeasuringU, has a blog post titled “6 things you didn't know about Heuristic Evaluations”. As part of his post, he, of course, mentions the famous Nielsen and Molich’s heuristics, but he also introduces four other sets of heuristics:

  • Bastien and Scapin created a set of 18 Ergonomic criteria
  • Gerhardt-Powals 10 Cognitive Engineering Principles; that we’ve just covered
  • Connell & Hammond's 30 Usability Principles
  • Smith & Mosier's 944 guidelines for the design of user-interfaces (from 1986)

Let’s see what else he mentions, since these also give pointers as to why so many professionals often fail to apply heuristic evaluation in the right way and as the right complement:

  • A heuristic evaluation needs multiple evaluators (three to five individuals) on board. Each evaluator is likely to find different problems. Hence, it is important that you involve other experts when running a heuristic evaluation and best if they are not deeply involved in the design.
  • Try to find double experts to participate in the heuristic evaluation. That is, professionals who are both experts in usability principles and the domain your product/service belongs to. If you’re testing a medical application, try to involve evaluators who know about the medical sector and its idiosyncrasies.
  • Again, and because it is really important, we want to insist on this: a heuristic evaluation should be done prior to and in addition to user-testing. Use heuristic evaluation to help your users while user testing. If you have found the main generic problems while running the heuristic evaluation, your users will encounter the real problems with them.

The Take Away

In 1996, scholars Gerhardt and Powals devised a heuristic technique offering powerful problem-solving for computer users. As designers, like many types of professionals, we can all-too easily end up with a bias that can cloud our judgment when we consider our users. Because we are close to our work and don’t want to insult our users’ intelligence, we can often presume that they’re “right there” with us and our designs. Users still need “handholding” for them not to become frustrated by a design.

The Gerhardt-Powals cognitive principles offer us a 9-point checklist to facilitate this “handholding”. As a designer, you should design having these points in mind. Once the designs are ready, you can also run a heuristic evaluation on your design to quickly pick up on areas that you may be too “close” to in your design (and world as a designer!) to notice.

Our users are human. Thus, you should design to avoid increasing their cognitive load. A good way to keep their perspective in mind might be to imagine if your design were a piece of emergency equipment, such as a defibrillator. Clear, concise instructions, aided by ambiguity-free illustrations (pictographs) in a logical sequence will show them what they need without derailing their train of thought and causing frustration.

Once your design is ready and you have created your artifacts with these points in mind, you should still run the 9-point heuristics process; think of it as a quality control safety check on your design. These activities must be done prior to involving users. While the cognitive principles shown here are a thorough set of criteria, nothing is a substitute for testing in the field. After all, your design will be there for users long after the evaluators have handed in their reports.

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