Watching Out for the Clever Hans Effect

During her summer holidays, I tried teaching carryover and borrowing (in maths) to my daughter. Like everyone else, she picked up carryover easily. But borrowing proved a harder nut to crack (no surprise there either). I’d be sitting next to her as she practiced and at one point, it looked like she had learnt borrowing too. A couple of days later, I wrote down a couple of subtraction questions and stepped away to attend to a few other things. When I returned, I found she had made many mistakes in subtraction/borrowing. What had happened? How could she have forgotten given that she was practicing every day?

Then I remembered this horse called Clever Hans. In the late 19th century, Wilhelm Von Osten started teaching his horse to count by tapping his hooves. Amazingly, the horse could soon do many maths problems, including fractions, multiplication, even working out dates! Sure, he wasn’t always right, but the accuracy rate was high enough for Germany’s board of education to take notice. They wanted to investigate closely, and Von Osten agreed. In 1904, the panel concluded Clever Hans was genuine.

But one psychologist, Oskar Pfungst, remained unconvinced. So he conducted additional tests, trying to eliminate and/or identify variables that might be affecting the outcome. Strangely, if the owner stood farther away when asking the questions, the accuracy of the answers decreased. But why? If the owner didn’t know the answer himself, the accuracy dropped down to… zero! Even if the owner knew the answer but was hidden behind a screen, Clever Hans’ accuracy fell to… zero. Was the owner signaling to the horse? Was all this just a fraud? But then why would the owner agree to so many tests? In fact, the same pattern of accuracy would occur even with others who asked the question instead of the owner! So what was going on?

Pfungst now turned his attention to the questioners. And voila!
“He almost instantaneously noticed certain shifts in the posture, facial expressions and breathing of the questioners whenever Hans tapped his hoof. With every tap, their tension seemed to increase; when the correct answer had been reached, it would disappear… Hans was taking these subtle shifts in tension as his cue to stop.”
The even stranger part?
“The most fascinating part of this was that both Von Osten and any other questioner involved had absolutely no idea that they were giving Hans cues. It was all completely unconsciously done.”
Today, the conveying of such unintentional cues is called the “Clever Hans Effect”.

Though I’ve not done any such rigorous study, I suspect this is exactly why my daughter was able to do her sums right… until I left the room. So now I give her the sums and walk out. If she gets it right now, (I hope) it means she’s learnt it!

Comments

  1. Ramiah KumarJune 16, 2017 at 5:02 PM

    Very nice.

    We look forward to such blogs where the child is learning and the parent is learning something about education meanwhile. The added benefit is that the blog-readers have the benefit of shared knowledge and the happiness how modern life enables sharing in ways unthinkable just about 50 years back!

    ReplyDelete

Post a Comment

Popular posts from this blog

Student of the Year

Image
As a toddler, my daughter loved Alia Bhatt’s songs, esp. the ones from Student of the Year . (That movie did have many good songs and well-choreographed dances). Fast forward to present day, when she is 12 yo. She rarely watches Hindi movies now, but one of the few ones she likes of late, Raja aur Rani ki Prem Kahani has, yes, Alia Bhatt.   If I had any hopes that there was anything to be read in the name of her toddler-time favorite ( Student of the Year ), they have been dashed. Our conversations come exam time are perfectly captured by this photo and its caption: In fact, the pic below captures how she and I look at her answer sheets – me intently, she with an expression of “It’s over, so why are you even looking at it?”   Of late, we pull her leg and tell her that she isn’t showing any signs of academic prowess, she’d better find a rich guy to marry. Some time later, she showed us this meme on the Internet: “Me No Study, Me No Care Me Go Marry Millionaire If He Die
Read more

Animal Senses #7: Touch and Remote Touch

Instinctively, we think touch is based on contact. Not entirely true, explains Ed Yong in Immense World – there’s a more important aspect than contact: “These incredible feats are possible through movement. If you rest a fingertip upon a surface, you can get only a limited idea of its features. But as soon you’re allowed to move, everything changes. Hardness becomes apparent with a press. Textures resolve at a stroke.” As you run your fingers over a surface, they hit the tiny peaks and troughs and set off vibrations in the mechanoreceptors at their tips.   At the tip of its snout, the star-nosed mole has many pairs of hairless appendages. It uses them to touch things around itself. Alive or dead? Food or ignore? It does these movements at an insane speed. In the time it takes to blink our eyes, the star-nosed mole can probe, identify and swallow its food. “Light may be the fastest thing in the universe, but light sensors have their limits, and the star-nosed mole’s sense of
Read more

The Retort of the "Luxury Person"

Image
Coming up with biting and witty retorts. It’s something we dream of, but rarely manage to pull off. Worse, the more we stew over the offending remark, the more likely we are to come up with that dream retort, as Calvin ruefully points out: During our last holiday at the Taj Resort, seeing my wife carrying towels to our poolside chairs, one of the kids there mistook her for a member of the staff and asked for a towel. When my wife narrated this to us, I did not imagine that my 8 yo daughter would come up with her own retort. But a day later, my daughter recapped the incident, an incident that didn’t even involve her in the first place , and said, “You know what I’d have told that kid who asked for the towel?”. And without waiting for an answer, she told us anyway: “I don’t work here. I too am a luxury person who is living at this resort. Go get your own towel.” We were highly amused by the phrase she had coined: “luxury person”. It certainly captures the kind of holid
Read more