Perhaps the most important goal of usability is that of minimizing the interaction cost, and it's common for many websites and applications to try to reduce the amount of steps—often, clicks—that a user must do in order to complete a task. However, interaction cost is more than just the number of clicks (or other physical actions)—it also involves mental effort. There are times when focusing purely on the number of steps actually backfires: instances when users are so accustomed to the "inefficient" process that streamlining it is perplexing and breaks the task flow. In those cases, paradoxically, the interaction cost is actually increased by the extra cognitive effort required to navigate the streamlined paradigm.

In a simplified equation: IC = P + M (interaction cost = physical + mental effort). It's not worth reducing P by a small amount if the corresponding M becomes much larger.

Expectations Are Based on Past Experiences

Humans often take the path of minimum effort, not because they are lazy, but because they attempt to be efficient and satisfy their many goals as fast and easily as possible. When they think or problem solve, people subconsciously match the current situation to past encounters in order to make decisions and perform actions. If in a similar situation a certain action has often been successful in the past, that action will be applied again in spite of the many other possible alternatives. (These other alternatives are often too weak to win the fight against the most practiced one.) Further, the result of that action is assumed to be exactly the same as the results achieved in the past—the past experiences turn into current expectations.

This subconscious process is allowed through implicit memory. Implicit memory is a type of long-term memory, where past experiences are used to inform actions without any conscious awareness. On the web, users rely on their implicit memory of every website they have ever encountered to know how to interact with the current site or application. When performing actions to complete tasks, users also depend on procedural memory: a subset of implicit memory related to process execution.  When a task is rehearsed a lot, it becomes part of the procedural memory: it's almost as if we had a dedicated "muscle" that deals with it. (Not surprisingly, a type of procedural memory that is dedicated to movement is called "muscle memory.") Our procedural memory is what allows us to effortlessly tie our shoes, ride a bike, and type a PIN on a website or at the ATM: we can complete these tasks on autopilot.

Practice Makes Perfect

Part of what enables us to execute complicated processes without conscious effort is the extent to which we have practiced that process. Repeating an action—ideally the same way each time—is how we learn and store that action into our procedural memory. Multiple instances of encountering a situation, taking a specific action (or set of actions), and getting the same result serves to reinforce the pattern and cement it in our memory.

Practice also is how we learn information and get it stored into our explicit memory that we access consciously. How much a piece of information has been used in the past determines its activation in the future.

In the digital world, this practice of particular patterns by users is the reason we recommend that designers follow established standards when creating an interface. Jakob's Law of the Web User Experience states that users spend most of their time on other sites; while on those sites they are practicing locating and using search boxes, clicking on checkboxes to filter lists, entering and submitting information on forms, and so on. When reaching your site, they expect it to function in the same way as on those other sites—any slight deviation from their norm snaps them out of autopilot and forces them to think and try to find an action that matches this novel situation. This is bad! We want users to stay in autopilot mode, and not exert extra effort thinking about how to use an interface.

Consider the activity of updating profile settings for a system: the standard procedure for completing this task is to navigate to some sort of form, go through each item and select the desired setting, and then save or apply the new settings. This set of actions has likely been practiced multiple times, with each system on which a profile is maintained. With this typical procedure in mind, let's now consider the following Email Settings form from Nextdoor.com:

Settings form on Nextdoor.com omits the Save button
The Email Settings page on Nextdoor.com does not allow users to follow the typical procedure for updating settings using a form. This deviation from standard form design forces the user to spend additional time and effort thinking about how to complete the task at hand.

What is missing from this otherwise fairly standard form? There is no Save button! How do we apply our changes so they are saved in the system? Computer-savvy readers may realize that the form is likely saving any changes whilst they are made, thus gaining efficiency by not requiring an extra save button press. However, most users are not this savvy, and even the savviest amongst us are more used to the pattern of having a Save or Submit button at the end of a form. This is an excellent example of how even the smallest deviation from a standard can cause confusion and increase cognitive load. By removing the Save button the designers have taken users out of autopilot mode, as the task can no longer be completed according to plan. Rather than clicking Save and moving on with their lives, users encountering this form must now spend time looking around the page for the omitted Save button and relate this new situation to any other similar past experiences in order to determine what action to take next. The reduction in the number of steps does not translate in a reduction of the interaction cost, since users must spend cognitive effort to find a new procedure for dealing with this less common pattern.

Respect Mental Models

The lack of any Save Changes functionality on a form not only fails to match the pattern of interaction for most forms, but also goes against the typical mental model for how digital systems store information. Over years of experience with technology, most users have learned that they need to explicitly tell a system to save their work or they risk losing everything since the last save. That being said, it's also very true that often people forget about saving documents (and autosave is a great feature that prevents many hours of grief and duplicated work). However, autosave does not need to replace save: they can both coexist. In the case of forms, most users assume nothing is really changed until a Save or Apply button is pressed, and navigating away from the form will revert any changes just as though they hit Cancel.

Users Crave Control

Similar to backseat drivers, users want to feel in control. Feelings of control can only occur when, in Don Norman's terminology, the system bridges both the gulf of evaluation and the gulf of execution: that is, it clearly tells the user what the state of the system is and how to manipulate the interface to change that state. Users need to be continuously aware of the current status of the system (one of the 10 usability heuristics). For users, seeing is believing: visual feedback must be displayed for every process a system undertakes. Every action, from exposing hidden content to communicating progress during a wait, must be clearly displayed in order for the user to understand anything is happening.

Taking away the Save button reduces users' control over the interface. Suddenly, the website is an autonomous entity that decides on its own how and when to do things. To give control back to the user, the system needs to show that it is not acting under its own accord, but it is merely responding to actions the user has initiated. In the NextDoor example, rather than autosaving only in the background, visual feedback must be displayed on the page to communicate to the user that the new settings have been saved as they are being selected.

Proposed redesign option adding visual feedback for saved content
Proposed update for forms on Nextdoor.com: In order to preserve the user's sense of control and understanding of the system status, visual feedback communicating that a new setting has been saved must be added to the interface. One solution would be to display the word Saved beside each field as it is changed, to tell the user that no further action on their part is required. An even simpler solution would be to add a standard Save button to the end of the form (and remove the autosave functionality or otherwise allow users to revert their changes easily).

Help Users Become Masters

While it is important to preserve known patterns of interaction and keep existing mental models in mind when designing, I don't mean to imply that innovation should never occur. Design standards are not intended to stifle creativity, but rather to aid users by decreasing the time and effort needed to complete a task. Why waste people's mental energy on irrelevant UI elements? If a new, more efficient way of completing an activity is possible, by all means try it! But, don't leave your users in the dark—help them learn the new pattern by understanding their expectations and clearly communicating information important to them. Only when people can understand the UI and what they must do to move forward and complete their task will they feel mastery over the interface. Our goal must be to keep users calm, confident, and in control as they interact with our websites and applications, by fully understanding and respecting how their minds process the information displayed and cope with patterns of interaction.

For more information on users' cognitive constraints and how to design accordingly, attend our full-day training course on The Human Mind and Usability.