Greetings, folks! Time again for an other Bootcamp entry! For this one, we’re going to talk about a cognitive bias officially known as the Observer-Expectancy Effect, but is commonly known to most as the Clever Hans Effect. So pull up a chair and let’s dig in, shall we?
Let’s start with, appropriately enough, the story of Clever Hans. Clever Hans was a horse. He may perhaps have been very clever for a horse, but not nearly as clever as many people thought he was.
Wilhelm von Osten, a retired mathematics instructor, began training Hans the horse sometime around 1900 and after about 4 years, in 1904, presented Hans to the world. And for awhile, Hans was a sensation.
You see, Hans could talk.
Well, not literally, but he could tap his hoof to represent numbers or letters, and it soon became apparent that this amazing horse could do complex math — not just addition or subtraction, but multiplication, division, and even work with fractions. He could communicate in complete sentences, spelling out the words letter by letter with hoof taps representing each letter. He understood calendar dates, music, even paintings, identifying master painters by name when shown representations of their work. And he could read (I guess not surprising, since he could spell, but questions could be presented to him equally well either verbally or in written form).
Pretty darned clever, eh? There are plenty of humans that would struggle with some of that.
So people began testing Hans, and found that even when von Osten wasn’t asking the questions, Hans got the correct answer. This was even true if von Osten wasn’t in the room with Hans.
Truly, Hans was a towering intellect among horses, apparently being just as intelligent as a human.
Or was he?
Soon after hearing of the amazing Clever Hans, Carl Stumpf, psychologist and founder of the Berlin Laboratory of Experimental Psychology, convened a panel (The Hans Commission) to look into the Hans phenomenon. The Commission, which included experts such as a horse trainer, cavalry officer, several teachers, a veterinarian, and a circus manager, looked at the available evidence and determined that there were no tricks involved and that whatever else was going on, Hans appeared to be answering the questions correctly without deliberate human trickery or fraud. The Commission then duly dispatched one of Stumpf’s volunteer lab assistants, Oskar Pfungst, to continue to investigate Clever Hans and see if he really was as clever as was claimed.
Pfungst began with the obvious, like having von Osten out of the room when Hans was questioned. But surprisingly, Hans passed such tests just about as well as he did when von Osten was present.
But then Pfungst moved to even more rigorous tests.
When Hans was given tests where he was “blinded” — no human was present in the room with him or visible to him, and he was just given placards with written questions or questions were asked from an adjacent room or from behind a barrier where Hans could not see any people, suddenly Hans was not so clever. He would tap his foot slowly and rather aimlessly, and be unable to answer even simple questions correctly (his accuracy dropped from an impressive 89% down to a mere 6% accuracy).
Pfungst had discovered Hans’ secret. He was indeed getting cues from the humans around him that were telling him when to stop tapping to get the correct answer — and get his sugar cube reward.
This isn’t to say that von Osten or anyone else was intentionally signaling Hans. But Hans had learned to cue in on human body language and even subconscious cues were enough for him to clue in on and get the right answer. So in his way, yes, Hans was very clever — at reading human body language. As long as Hans could see someone while he answered so that he could see their reactions to his tapping, he had a pretty good chance of getting the right answer (as long as the person he could see knew the answer!).
And so, the Observer-Expectancy Effect was discovered, though it didn’t get that moniker right away, and indeed most people even now just know it as the “Clever Hans Effect.”
So, what is it, exactly?
It’s an effect where a researcher subconsciously influences a test subject (though obviously, this doesn’t have to happen in a research environment. Clever Hans was being influenced by his trainer and other people before the psychologists showed up to test him). This can be a positive or negative influence, influenced by the researchers’ own internal expectations. And it is not limited to animals. People are social critters, and we ourselves cue off of the body language and signals others give off, so it’s very possible for a researcher to human subjects in this way. This is why experiment design is very important and double blind studies (where both the researcher and subject are unaware of what treatment or assignment the subject is getting) are a gold standard.
Where do we run into this? Well, we probably are doing this with our pets, for one. I mean, my cat probably IS smarter than me, (he certainly has me wrapped around his paw, at least), but I’m sure all the others are taking cues from owners to get what they want. But we could be encountering this on a subtle level all day long, really, on both sides of the equation, as we both give off subconscious cues to others and they do the same to us, and we in turn react either consciously or subconsciously to those cues. The difference being that when that happens during daily life, it’s called “being human” as opposed to participating in some kind of research study.
Epilogue: So whatever became of Clever Hans? Wilhelm von Osten never agreed with Pfungst’s findings, convinced that Hans was indeed possessed of human level intelligence, and continued touring with Hans and doing demonstrations (von Osten never charged anything for his demonstrations, so his motive wasn’t profit). After von Osten died of cancer in 1909, Hans passed through the hands of several owners and then was drafted as a military horse in the early months of World War I and may have died or been killed in 1916 while in service — history is not definitive on Hans’ final fate. In any case, Hans’ trail disappears in 1916. A sad end for a clever horse.
That’s it for today, folks. Maybe raise a glass to Clever Hans, who no doubt was a very clever horse, just not in the way his trainer thought. And maybe kick back and watch some Mr. Ed reruns. Or if you’re in a more serious mood, maybe read or watch War Horse.
Until next time!
And if you’ve enjoyed reading this, consider partaking of some of my other past entries in my Bootcamp series, wherein I explain a logical fallacy, cognitive bias, or expound upon some other aspect of critical thinking! See below for links!
Prior Bootcamp Installments
Logical Fallacies Bootcamp:
The Strawman
The Slippery Slope
Begging the Question
Poisoning the Well
No True Scotsman!
Ad Hominem
False Dilemma
Non Sequitur
Red Herring
Gamblers Fallacy
Bandwagon Fallacy
Appeal to Fear
The Fallacy Fallacy
Appeal to Personal Incredulity
Appeal to Authority
Special Pleading
Texas Sharpshooter
Post Hoc
Appeal to Nature
Furtive Fallacy
Alphabet Soup
Middle Ground
Relative Privation
Cognitive Bias Bootcamp:
Bystander Effect
Curse of Knowledge
Barnum Effect
Declinism
In-Group Bias
Hindsight Bias
Survivor Bias
Rhyme-as-Reason Effect
Apophenia (& Paradoleia)
The Dunning-Kruger Effect
Confirmation Bias
Anchoring Bias
Inattentional Blindness
The Frequency Illusion (AKA the Baader-Meinhof Phenomenon)
G.I. Joe Fallacy
Critical Thinking Bootcamp:
Sea Lioning
Occam’s Razor
The Gish Gallop & Brandolini’s Law
Lateral Reading