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Five Steps To Usable Product Design

(This article, co-written with JD Albert, first appeared in Appliance Design magazine.)

For tech-enabled hardware like consumer electronics, wearables, home appliances, and medical devices, displays are the cornerstone of user experience.

With so much emerging in this realm, how do you know which display technology is right for your product? Brand impact, cost, and screen capability are core drivers for all specs, including display and user interface, but user and usability requirements – the human factors of a product – are the quickest route to the best solution.

When it was born around World War II, the human factors field was primarily concerned with industrial and military contexts. (When Rosie the Riveter replaced Ralph, factory workstations needed to be reconfigured; and as Ralph went off to war, engineers soon found that he could become the weak link in higher tech military systems.) The notion of making the product “fit” the user began spreading to consumer products shortly after the war. The rise of computers and computing in the ’80s gave human factors a boost and shifted the focus to displays and interfaces. It has since become an important point of differentiation for any product.

Human Factors 101

Human factors sit in the intersection of product, tasks, environment, and user.

Here are five steps to figuring out the human factors requirements for a tech-enabled appliance or a consumer electronic device:

1. Who are the users?

On the first day of any Human Factors 101 class, you might find the professor drawing a Venn diagram on the board with four circles tagged “product,” “tasks,” “user,” and “environment.” Human factors sit in the intersection of those four areas. The first step to designing a useable product is to analyze the user. Adults, kids, older adults? Age will influence the height of the user and the position of the display.

The best practice in human factors is to design for a wide range, for example, the fifth through 95th percentile of potential users.

As visual abilities diminish, people need bigger fonts and higher contrast, which dictate the size of the screen and the type of display technology. It will also influence the type of interaction with the display since older adults may be unfamiliar with touchscreens and need to rely more on the tactile feel of buttons.

environment in human factors and usability

Will your users be operating your device outdoors?

2. Where are they using it?

The environment where the device or appliance will be used is another major factor. Used outdoors or in a bright environment, an emissive display (like an OLED or backlit LCD that gives off its own light) needs to be able to crank up the brightness to overcome the ambient light.

As soon as the user has to shield the screen from light with his or her hands in order to read the display, you’ve lost the usability battle.

Of course, reflective displays like some LCDs or electronic paper displays like E Ink don’t have this problem outdoors, but the flip side of this is that they will need lighting when used in dark environments. In a typical domestic environment, standard LCDs with LED backlights work well, as do simple LED based displays such as the seven segment modules used on microwaves and refrigerators.

3. What are the social factors?

Is the appliance for public or private use? Are there any security concerns – such as a screen in an ATM? If the appliance is meant for public use, then a wide-viewing angle will be critical. Look for newer LCDs with IPS (in-plane switching) technology. Products designed to be used by a smaller group of users such as family use or a home appliance or products designed for use by a single user may allow for customization or system memory for the user’s preferred settings.

ethnographic research for usability

We conducted ethnographic research with NYC and Philly fire departments’ HazMat teams to design usable digital and physical interfaces for this chemical-detection device used by first responders wearing bulky gloves.

4. What tasks do the users need to accomplish?

User researchers go out into the field and conduct ethnographic research on competing and preceding products. If a product is brand new, they look for unmet needs and think about how to solve those with a completely innovative product. We’ve done user research on kitchen appliances and found customers confused and annoyed by complex user interfaces and overly bright displays.

The number of different tasks and the level of complexity of those tasks directly relates to the approach of the user interface design.

How many options do there need to be and how complex is their presentation? How much information needs to be displayed at any given time? If it’s a washing machine, is your interface as simple as displaying three general water temperatures (cold, warm, hot) and associating them with wash cycles? Or will the user want to control the water temperature down to the exact degree?

In some cases, the display is there simply to provide feedback – for example, on an oven with LED indicators that disappear when that cycle is inactive. In others, the display plays an active role in the interaction. Hiding information users don’t need is one great way to use displays to make products at least appear simpler, but avoid the temptation of using a smaller screen than necessary and burying functions too many layers deep in the interface.

Tesla's dashboard screen

Tesla’s massive dashboard screen.

Are there other special considerations? More and more cars are embedding large interactive dashboard displays. In this scenario, when a person is driving, a small touchscreen is going to be difficult and potentially dangerous to navigate. (That’s one reason why the Tesla has a massive 17-inch dashboard screen.) Keep in mind that if users need to operate controls blindly – for example, while keeping their eyes on the road, physical buttons, rather than a touchscreen, may be the way to go.

If devices are intended for first responders and healthcare workers who need to perform actions wearing gloves, substantial hardware controls (i.e., fat buttons) paired with a display screen may be the answer. Another option would be a screen using PCAP, projective capacitive technology, which works through some gloves.

user expectations and usable product design

Once you sort out human factors requirements, it’s time to factor brand values and user expectations into the equation.

5. Gauge user expectations.

A lot of consumer decisions are made less by user needs than by user wants. Tablets and smart phones are the new standard by which people judge displays. The modern user will continue to expect the look and feel of the latest mobile gadgets from all tech-embedded products.

Still, user expectations remain higher in some product categories than in others. The average person checks out friends’ and family members’ phones and consumes some amount of tech news. Those same users are probably only intimately familiar with their own refrigerator and maybe two others (at a rental house, perhaps, or at their in-laws). There are product categories people think about all the time, and then there are the ones they don’t think about until their current model becomes irreparable.

Designers and their clients need to invest in user research to determine consumer expectations and weigh them against needs. How do you apply the lowest tech screen possible to meet the functionality and pricing requirements of your product – and still appeal to the user without looking dated?

Design bridges the passage of information between the user and the product.

The circles in your Venn diagram might be called “user expectations,” “human factors requirements,” and “brand values.” To fill them in, you need to know what information the machine needs to convey to the user, how much input the user needs to impart to the machine, and how that back and forth should look and feel. Once you’ve filled in those circles and found the overlap, you’ve reached a good starting point. Now, get designing.