When the user wants to know what’s going on around them. Take advantage of mobile devices’ sensors such as location, device orientation, and ambient light to personalize the experience where appropriate (and with permission, of course!)  When the user is looking to be entertained, think beyond the task-focused features. What can you offer users when they leisurely browse? I might add a few more categories that have emerged since Josh wrote that book early on in the smartphone era:

• Extended engagement: When the user fully engages with the content for a long time, scrolling, tapping or swiping endlessly.
• Interrupted attention: When notifications pull users back to check up on activity, status updates, or anything else. Note this is not always good, as notifications notoriously pull users back for no urgent reason other than for the company’s app engagement monetization needs.

In that last category, Microsoft offers a set of guidelines called “Respecting Focus.” They fall into five main areas: 1. Understand urgency and medium: Technology communicates in many ways: pop-ups, blinking lights, sounds, and vibrations. Are they all needed? Match the urgency of a notification with the urgency of the communication. 2. Adapt to the customer’s behavior: How a customer interacts with each feature or part of your experience will change over time.  3. Adapt to context: We all focus, filter, and consume information in unique ways. We filter out different information. These preferences and capabilities can rapidly change based on context. Because of that, how a person interacts with each feature or part of an experience will change. Can your system learn from how people interact to modify the way it communicates? 4. Enable the customer to adapt: Personal experiences should suit each individual. Customizable features help customers feel empowered and in control of their devices. Many alerts on computers today are difficult to tune out or turn off. It can get overwhelming if multiple applications all send alerts simultaneously. Better systems have ways for users to control the type and timing of notifications.