You drive home and park. Your car is full of groceries and other shopping, which take many trips to bring into the house. Five minutes after you drove in, you are still making trips to the car. Is the door locked or unlocked?” What if I told you that 87% of people got this question wrong? Sensors and “smart” devices for your home may hold the promise of making life more convenient, but they may also make it harder to understand and predict things like the state of you “smart” door lock in common situations like the one above. Want to give it a try?

The main issue at hand is “feature interaction.” This is the idea that some of the features of your future smart home may want one thing (i.e., door locked for security), while others may want another (i.e., door unlocked for convenience). Software engineers who program future smart homes must come up with a clear set of rules for a device like a smart door lock so that it always behaves in clear and predictable ways. But, what is clear and predictable to a computer may not be clear and predictable to a person. My collaborator (Pamela Zave from AT&T Labs Research) and I found this out the hard way by running a study asking people to predict the state of their door lock in scenarios like the one above based on three rules applied to the interaction between four features. None of the people in our study got all the questions right (and the one who got the closest was a lawyer!). See how you do by taking the 15-question quiz below:

How did it go? People in our study made some common mistakes that we describe in our paper. The bottom line is that “feature interaction” resolution rules that are simple for computers may require more effort for humans to understand. We think at the core of this may be a mismatch between logic and intuition. People intuit that an automated smart door lock should err on the side of keeping their door locked even in situations where it may be more convenient (and more similar to a regular non-smart door lock) to keep the door unlocked. It is important for researchers from multiple fields to work together to understand people’s intuitions and errors before programming future home systems, so that we won’t be left wondering whether our door is locked or unlocked!

Want more detail? Check out our CHI 2017 Publication.

Written by

Svetlana “Lana” Yarosh is an Assistant Professor in the Computer Science & Engineering Department at University of Minnesota. She has two Bachelors of Science from University of Maryland (in Computer Science and Psychology), a Ph.D. in Human-Centered Computing from Georgia Institute of Technology, and two years of industry research experience with AT&T Labs. Her research falls primarily in the area of Human-Computer Interaction, with a focus on Social Computing and Child-Computer Interaction. She designs systems that enhance strong-tie social relationships to create stronger families, support individual health and wellbeing, and provide a stage for personal and community growth.


2 Responses to “87% of People Got This Question about Their Door Lock Wrong!”

  1. Bjarne Dreier

    14/15 and I still don’t get why the door is unlocked in the drive-up scenario…

    • Lana Yarosh

      Lana Yarosh

      Sure! That’s the one most people got wrong. Let me walk through it.
      – When your car drives up, the “Hands-Free Drive Up” feature expresses the preference to unlock the door. There isn’t a higher priority feature requesting that the door lock, so the door will be unlocked
      – After 3 minutes, the “Hands-Free Drive Up” feature will stop expressing this preference. Now NO feature is expressing any preference. According to the “Don’t care means no change” rule, the door lock should stay in whatever state it currently is. It’s unlocked, so it will stay unlocked (until some other feature expresses a preference to lock it).

      Interesting thing about this question is that the door lock behaves in a way that people universally prefer (i.e., it’s convenient that the door didn’t lock itself halfway through you lugging in groceries), BUT it’s not the way that they EXPECT it to behave (probably because most people assume that the door has some sort of a “default” lock feature).

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