Not all features are carefully planned; some are accidents. Not all accidents are bad; some turn out to be great. When a new product has a great accidental feature, everybody wins.

What about when the old product being replaced had a great accidental feature, and we didn't realize it?

Books — Kindle vs. Paperback

A study was recently conducted comparing people reading a novel on a Kindle DX against a group reading the same novel in paperback, and then giving them comprehension tests. The Kindle readers performed as well as the paperback readers on most measures, but the Kindle readers were less able to list out 14 specific plot points in the correct chronological order. The lead researcher speculates on the cause:

When you read on paper you can sense with your fingers a pile of pages on the left growing, and shrinking on the right…. You have the tactile sense of progress, in addition to the visual….

The idea is that the reader is subconsciously aware of how far through the story she is as she takes in each new plot point and her brain files it away appropriately. If true, this is a great feature, but a complete accident. We never see it advertised on product pages:

Subconscious Progress Tracker (TM) — know where you are without trying, leading into increased comprehension!

It’s not a designed feature; it’s a byproduct of how books are made. Meanwhile, here is a very intentional feature Amazon advertises for its latest Kindle:

Read Comfortably with One Hand Thinner than a pencil, lighter than a paperback — and over 30% lighter than iPad mini. Comfortably hold Kindle Paperwhite in one hand for long reading sessions.

One-handed operation is indeed a great feature, but it means we lose the Subconscious Progress Tracker, the feature we didn't know we had.

Product and Byproduct

Products are designed to deliver certain benefits at some acceptable cost. (Cost can include price, limitations or difficulties of use, fuel or other input requirements, etc.) However, any specific design can have byproducts that are benefits or costs in their own right. The difference is that these were not an intentional part of the design, and we may not even be aware of them.

Consider the paperback above; we can plot some of its attributes on a chart:

When paperbacks were invented, designers were not concerned with killing trees or aware of the comprehension benefits of pages. These costs and benefits were byproducts of the design that only became apparent much later.

The Kindle designers specifically targeted the need for two hands and for light (with their Paperwhite model), and ebooks naturally do not kill trees, but we were all unaware of the chronology comprehension benefits until now.

This pattern can occur anywhere. Below are two more examples.

Traffic Lights — LED vs. Incandescent

Incandescent bulbs are not “efficient” in that only about 5% of the energy they consume is converted to light. The rest is converted to heat, typically an unwanted byproduct. However, sometimes that heat serves a purpose. Turns out incandescent traffic lights contain this accidental feature:

Snow Melters (TM) — each bulb emits enough heat to melt any accumulated snowfall, providing excellent visibility in all weather conditions!

Many cities are now installing LED traffic lights, which are so power efficient they don’t produce enough heat to melt snow, leading to decreased visibility and even some car accidents.

Cars — Hybrid vs. Gas

Toyota Prius, no pedestrians around

Internal combustion engines are loud. Noise is not the purpose, of course; it’s just a byproduct. Electric motors, on the other hand, are very quiet in comparison. Some people really enjoy that aspect of driving the Toyota Prius, but there have also been some accidents where blind or distracted pedestrians walked in front of hybrid cars because they didn't hear them coming. Gas-powered cars had an accidental feature we didn't realize:

Vehicle Proximity Notification System (TM) — automatically alert pedestrians that your vehicle is nearby, increasing safety and preventing accidents!

Not to be accidentally outdone by its gas-powered competition, Toyota added an artificial noise generator to the Prius (coincidentally also called Vehicle Proximity Notification System). You can hear it below:

Two steps forward, one step back

It’s worth remembering that these products do take many steps forward. The Kindle can deliver new books to you instantly, store hundreds of books, search the text, etc. LED traffic lights save power and don’t require maintenance to change the bulbs nearly as frequently. Hybrid cars have lower greenhouse gas emissions.

Meanwhile, the backward steps can be fixed. The Kindle shows a progress bar at the bottom; maybe it will become second nature for readers to glance at it. Maybe traffic lights can be shaped differently to avoid snow accumulation, or maybe they can heat up only when necessary. Toyota already added weird alien sounds to the Prius.

Ultimately, this is not an argument against progress. We just can’t always tell ahead of time what is an accidental feature and what is just nostalgia. People are resistant to change. People used to say they preferred CDs to MP3s, but it seems many people can do without liner notes after all; they just needed portability, playlists, individual track sales, and a host of other new features. The only way to get there is to experiment and iterate.