Lake Disappointment
To share a personal anecdote, this article was born while I was walking home from my dentist’s office. I learned some not-so-great news about teeth and decay, and all the way home my brain entertained itself with the excellent two-line poem it wrote:
well, this appointment
— was a disappointment
This then got stuck in my mind for a little while, and when I learned about “Lake Disappointment” having been the actualname of an actual lake, I knew what to do. (Write an article for PsychToday.)
And so it goes: at the turn of the century, water determined everything in inland exploration. It decided where livestock could survive, which in turn limited how far expeditions could travel. For entire routes through the desert, fresh water decided whether it was worth leaving home at all.
When Frank Hann, the explorer who mapped large areas of Western Australia, finally reached a vast lake marked by promising rivers and geographical patterns, he hoped he had found a substantial freshwater source. Instead, he discovered an enormous salt pan, undrinkable and effectively useless as far as the expedition was concerned.
He named this body of water “Lake Disappointment.”
The name then went on to appear in maps and government records and persisted for more than a century. The lake was an official “disappointment” until Western Australia restored the traditional Martu name, Kumpupintil, in 2020.
Naming things sounds like a serious enterprise. Most of our surroundings have names that are either pompous or decidedly neutral, as if they emerged naturally alongside the terrain. “Lake Disappointment,” is the opposite — it’s a real human moment: the excitement of finding the lake, and the petty name-calling when it turned out to be less than expected.
Prediction engines
Notice how the lake isn’t objectively disappointing. As far as bodies of water go, you’d be hard pressed to find anything wrong with this one. But, as humans, we don’t evaluate anything in isolation. We evaluate things against an expectation: our idea about what a thing should look or behave like.
Hann felt let down by the lake because his prior experience in geography pointed toward it being a freshwater lake. The mismatch between that prediction and the salt pan was, by definition, disappointing.
Neuroscientists have found that the brain is quite interested in this gap. In the 1990s, Wolfram Schultz and his colleagues discovered that dopamine-producing neurons in monkeys responded not simply to rewards, but to how those rewards compared with what the monkeys expected. An unexpected reward produced a strong response, but one that arrived exactly as expected produced little response.
The brain is continuously updating itself based on surprises. Predictions and prediction errors are an important part of that learning, and a sudden drop in dopamine signals to us that we’re about to encounter a teaching moment.