The doorbot is a both a physical device and an accompanying software application for mobile devices. In this post, I’m focusing on the physical device component as an example of good design. We bought the doorbot for our building when our buzzer system broke. The physical device mounts to the front of the building next to the door and looks like this:
The doorbot system works as follows:
- A visitor arrives at the resident’s front door and pushes the doorbell button on the wall-mounted device, which sends a push notification to the resident’s mobile phone via the doorbot mobile app.
- The resident opens the doorbot app, engaging the video camera on the wall-mounted device as well as the speakers and microphones on both the resident’s mobile phone and the wall-mounted device.
- The two users then engage in a video conversation via mobile phone and wall-mounted device.
The doorbot system is NOT a buzzer—it doesn’t allow a resident to unlock the door. And it’s not a traditional doorbell in that the ring function only takes place on the resident’s mobile phone in the form of a push notification. Also, the video function is strictly one-way—only the resident can see the visitor via the device’s camera and not the other way around.
Good design according to Norman might be summarized as “easy to figure out what to do” and “easy to tell what is going on” and I think the wall-mounted device succeeds in both of these areas. Its interface is designed for familiarity. There are three components to the interface: a prominent button, which evokes a doorbell; a prominent video camera, which evokes a traditional video intercom system; and a prominent microphone and speaker, which both in their placement at the top and bottom of the device and in their “parallel lines” design follow well-known design conventions of telephone headsets and mobile phones.
Just looking at the device, a user should know what to do and how it works. Norman would say this sense of familiarity is a function of a design that successfully harmonizes its system image (a doorbell meets video intercom system) with the user’s prior knowledge or mental model how doorbells and video intercom systems work as well as what they look like. It minimizes the gulf of execution by making the system image so visible and easy-to-understand and by constraining action to the pushing of a button, as the button is the only component of the interface that’s interactive.
At the same time, the design minimizes the gulf of evaluation by providing clear feedback to let the user know what is going on. It does this in the form of both audio and visual feedback. When the visitor presses the doorbell button, the device makes a ringing sound like a doorbell and the light ring surrounding the button flashes, indicating that the resident is being called. When the resident picks up, the light ring switches from flashing to a solid blue light, indicating the video conference has been engaged. And when the resident hangs up, the blue light turns off, indicating the conference has ended.
Norman mentions in his book how good design obviates the need for labels or instruction manuals and I think the doorbot, with no visible labels or explanatory text at all incorporated into its design, is a great example of this.