Lighter, not faster

I keep hearing variants of this complaint lately:“This (tool / workflow / service / slot machine) is slower than me doing it manually. Therefore, it's not worth using.”These people are missing the point. Speed is easy to measure - that’s great. But focusing on speed overlooks the importance of subjective effort and mental load.Let's talk about grocery stores, naval signaling flags, and the value beyond time saved.The grocery store self-checkoutIn the grocery store, do you choose a human cashier or the self-checkout machine?People who prefer self-checkout often believe that it's faster. But in my highly-scientific study (loitering in the soup aisle with a stopwatch, n=24), the fastest self-checkout user was only equal in speed to the average cashier in scanning items. Once you add in the time to bag items and pay (not to mention "unexpected item in bagging area"), most people have no chance to outpace a human cashier.The true value of the self-checkout is to offload social effort, the…