The example on the left has linear motion and looks ‘bad.’ The first example up top has eased motion and looks ‘good.’ All three above examples have the exact number of frames and take place over the exact same amount of time. The only difference is in their easing.

As designers concerned with usability, we need to require of ourselves rigor and inquire, aside from aesthetics, which example supports usability more?

The case I am presenting here is that a certain degree of skeuomorphism is inherent in easing. You can imagine an ‘easing gradient’ wherein behaviors that fall outside user expectations result in less usable interactions. In the case of properly eased motion, users experience the motion itself as seamless and largely invisible — which is a good thing in that it is non-distracting. Linear motion is visibly obvious and feels somehow off, unfinished, and jarring, and distracting.

Now I’m going to completely contradict myself here and talk about the example on the right. The motion isn’t seamless. In fact, it has a ‘designed’ feel to it. We notice how the object lands. It feels different, yet it still feels more ‘correct’ than the example with linear motion.

Can you employ easing and still have it not support (or worse case undermine) usability? The answer is yes, and there are several ways. One way is timing. If your timing is too slow (mushy to borrow from Pasquele), or too fast, you can break expectation and distract user attention. Similarly, if your easing is misaligned with the brand or overall experience, this can also negatively impact expectation and seamlessness.

What I want to open you to is a world of opportunity when it comes to eased motion. There are literally an infinite number of ‘easings’ that you as a designer can create and implement in your projects. All of these easings have their own expectation response they trigger in users.

To summarize: when to use easing? Always.

You can learn more on my easing hypothesis in my article, ‘The irony of usability and linear motion.’

Principle 2: Offset & Delay

Defines object relationships and hierarchies when introducing new elements and scenes.

Offset & Delay is the second of only two UX in Motion Principles that is influenced by Disney’s Animation Principles, in this case from ‘Follow Through and Overlapping Action.’

It is important to note, however, that the implementation, while similar in execution, differs in purpose and outcome. While Disney’s Principles result in ‘more appealing animations,’ the UI Animation Principles result in more usable experiences.

The utility of this principle is that it pre-consciously sets the user up for success by ‘telling’ the user something about the nature of the objects in the interface. The narrative in the above reference is that the top two objects are united and the bottom object is separate. Perhaps the top two objects could be a non-interactive image and text, while the bottom object is a button.

Even before the user registers what these objects are, the designer has already communicated to her—through motion — that the objects are somehow ‘separate.’ This is extremely powerful.

In the above example, the floating action button (FAB) transforms into header navigation elements comprised of three buttons. Because the buttons are ‘offset’ from each other temporally, they end up supporting usability through their ‘separateness.’ Said differently, the designer is using time itself to say — even before the user registers what the objects are — that the objects are separate. This has the effect of telling the user, completely independent from the visual design, part of the nature of the objects in the interface.

To better show you how this works, I’ll show you an example that breaks the Offset & Delay Principle.

In the above example, the static visual design tells us that there are icons over a background. The presumption is that the icons are all separate from each other and do different things. However, the motion contradicts this.

Temporally, the icons are grouped into rows and behave like a single object. Their titles are likewise grouped into rows, and also behave like a single object. The motion is telling the user something other than what her eyes see. In this case, we can say that the temporal behavior of the objects in the interface are not supporting usability.

Principle 3: Parenting

Creates spatial and temporal hierarchal relationships when interacting with multiple objects.

Parenting is a powerful Principle that ‘relates’ objects in the user interface. In the above example, the ‘scale’ and ‘position’ property of the top or ‘child’ object is parented to the ‘position’ property of the bottom or ‘parent’ object.

Parenting is the linking of object properties to other object properties. This creates object relationships and hierarchies in ways that support usability.

Parenting also allows designers to better coordinate temporal events in the user interface, while communicating to users the nature of the object relationships.

Recall that object Properties include the following — Scale, Opacity, Position, Rotation, Shape, Color, Value, etc. Any of these Properties can be linked to any other Properties to create synergistic moments in the User Experience.