By Jonny Lupsha, News Writer

Australia has accidentally released millions of A$50 notes with a misspelled word, as reported by Reuters. Ironically, the word “responsibility” is the culprit, missing its final “i” and appearing as “responsibilty” three times on each bill. However, making mistakes is ingrained into human nature.

According to the Reuters article, the A$50 note is roughly equivalent to $35 U.S. dollars and is the most frequent note of currency in Australia, accounting for nearly half the printed money in circulation. Despite the embarrassment that employees of Australia’s central bank may feel, the human brain is prone to making mistakes all the time—and not just with language. Optical illusions, forgetfulness, and many other gaps in our receiving and retention of information play tricks on us every day, because the brain often learns via trial-and-error and experimentation methods called heuristics.

The Availability Heuristic

One trick our brains play on us all the time is called the “availability heuristic.” The availability heuristic concerns how readily we can access learned information in our brain. Dr. Patrick Grim, Distinguished Teaching Professor of Philosophy at State University of New York at Stony Brook, offered a simple question to serve as an example. “Are there more English words that start with the letter k or more English words that have the letter k in the third position?” he asked. “If you’re like most people, you said there are more English words that start with the letter k.” Dr. Grim said this is because it’s easy for our brains to immediately think of words that begin with a letter—in this example, words like king, key, or kite—rather than conjure words that feature that letter as the third letter of the word, which in this instance would be ink, bike, and so on.

“In fact, there are about three times as many English words that have a k in the third position,” Dr. Grim said. “It’s a lot harder to think of words in terms of a third letter rather than a first letter, but that has nothing to do with how many there are. We take how easy it is to think of something to indicate how common or probable something is, and that’s where we go wrong.” The designer of the banknotes in Australia, for example, may have seen the misspelled “responsibilty” and, recognizing the arrangement of most of the letters, simply overlooked it because they had the word pictured in their mind already rather than take the time to examine it letter by letter.

The Anchor-and-Adjustment Heuristic

“Memory can often be influenced by how a question is phrased,” Dr. Grim said. “It turns out the same holds for rational calculation.” When someone asks us a question, the nature of the question often has a kind of starting point, also known as an anchor. Dr. Grim mentioned another study in which a group of people were asked the following two questions: “What percentage of African nations do you think are members of the United Nations? Is it more than 10 percent?” Here, the anchor of the question is the 10 percent, and he said the answers came to an average of 25 percent. Next, another group of people were asked, “What percentage of African nations do you think are members of the United Nations? Is it more than 65 percent?” Given the 65 percent anchor from which to consider their answer, the average answer was 45 percent.

The correct answer is around 93 percent, but the interesting thing is the disparity of the results. It seems the phrasing of the question is what produced such drastically different answers. When asked for a number and provided a very low anchor, those tested rounded up to a safer, less extreme number. When given a high anchor, they backed off. This is called the “anchor-and-adjustment heuristic.” In the case of the Australian bank note, it had many similar-looking letters near the end of the word “responsibility”—the i-l-i-t series of similarly shaped characters lined up closely with one another. The designer of the bill may have seen the ending of the word and initially thought it looked like one of the “i’s” was missing, but then second-guessed their original thought and decided that the correct letters were all there in the word.

There’s a reason we so often say things like “to err is human,” or “it’s okay; everybody makes mistakes.” As we settle into familiar practices or become overconfident, or as we second-guess ourselves into making mistakes based on anchors, these things happen all the time.

Dr. Patrick Grim contributed to this article. Dr. Grim is Distinguished Teaching Professor of Philosophy at the State University of New York at Stony Brook. He graduated with highest honors in anthropology and philosophy from the University of California, Santa Cruz. He earned his Ph.D. from Boston University.