Feeds:
Posts
Comments

Posts Tagged ‘clever hans’

Interesting report from Ben Goldacre today about drug sniffer dogs used by police. Which might not leap out at you as a fascinating source of potential gossip, unless you have a better sense of these things than I did.

But it’s turning out that the Clever Hans effect might play a bigger role in sniffer dogs’ drug detection than was previously thought. That is, the human handlers’ expectations of where the drugs are might have at least as much impact on the dogs’ behaviour as the actual scent of drugs.

So, if you look like the sort of person who might have drugs on you, it’s possible that you’re just as likely to be barked at than someone who looks innocent but is smuggling dope through customs.

It’s not the scariest affront to civil liberties I’ve heard this week – I doubt anyone’s going to be arrested just because a dog growled at you if you’re not actually carrying anything illegal (though more horrible things have happened). But as Ben points out, it highlights the “theatre” aspect of much of what passes for important national security these days.

One thing I’m left wondering, though, is how sniffer dogs’ efficiency could be improved. I mean, I have no idea how they’re normally trained, or exactly what they’re picking up on in their handlers that makes them think they should take a particular interest in the guy with the beard – but are they perhaps learning these cues in the training itself?

If, when the dogs are learning what scents to look out for and how to respond when they track one to the source, they’re always in the presence of handlers who know exactly where the drugs are that they’re supposed to be finding, then maybe it only makes sense for them to also associate certain human behaviours with the items they should respond. In which case, there may exist a way to re-design their training, so that the only thing they’re cued to react to is the smell of drugs.

Anyone who knows anything about how this kind of thing actually works should feel free to educate me, as ever.

Advertisements

Read Full Post »

Let’s get one thing straight first of all. Animals are stupid.

Oh, don’t look at me like that. It’s not like it isn’t obviously true, and they’re too dumb to know they’re being insulted anyway. Even the ones I like are complete idiots. I’ve seen two-year-old kids who can talk better than any cat; I’ve watched dogs repeatedly fall for the same trick where I pretend to throw a ball, and every time they bounce away with moronic excitement chasing after nothing; we all know how terrible monkeys are at trying to move a piano; and don’t get me started on the legendary inability of voles to solve even the most rudimentary cryptic crosswords, no matter how simply and slowly you explain it to them.

I’ll admit that they’re not universally inept. Many of them can capture and tear apart a fast-moving hunk of raw meat more efficiently than I’m ever likely to; they’re often enviably cute; and those spiders which can leap out and grab something faster than you can blink are pretty cool. But in general, the point stands.

Our mighty human brains are the reason we’ve so easily and inevitably wrenched control of the world from Mother Nature’s puny green fingers, and the only time we ever deign to be impressed with the intelligence of one of her lesser creatures is when we’re patronisingly judging them by their usual standards of dumb-assery. We’re amazed whenever they show any slight proficiency for a skill at which every human is assumed to be naturally capable. This is why things like dolphins cleaning their tank, cats leaning not to crap in your shoe, or a horse being able to count to five by clopping his hoof cause such a stir.

Thing is, even then we’re giving them too much credit.

Clever Hans was a horse that wowed audiences in late 19th century Germany, by tapping out the answers to some really easy maths problems. Someone would ask the horse, say, “What’s three plus two?” and he would tap his hoof five times. I mean, I’ve seen four-year-old humans solving quadratic equations, but whatever.

Okay, so I am being overly disparaging. The maths is hardly impressive, but if a horse can really understand human words, and the syntax which holds them together in a sentence, that would be worth knowing. You’d start being more careful what you said around them, if you knew they might actually understand it, and be able to use their hooves to gossip about you later in Morse code or something. So, it caught people’s attention, because nobody had previously known of any animals that could do this, even if it does credit a simpleton quadruped way too highly naming it “Clever” for being able to add single-digit numbers.

But it caught a few scientists’ attention too, and those scientists started doing what scientists will tend to do when a new discovery is supposedly made – sticking their noses in further than anyone invited them and trying to see how true it is.

They wondered, not unreasonably, whether Hans mightn’t be getting his hoof-tapping cues from somewhere other than his unprecedented equine cognitive powers. No horse had ever shown any signs of this level of mental acuity before, or even anything close. I mean, look at how some of these questions were phrased: “If the eighth day of the month comes on a Tuesday, what is the date of the following Friday?” Now granted, as far as the mathematics goes, we’re still about on a par with modern GCSE papers. But that’s some fairly sophisticated sentence structure there, with the conditional clause and everything, not to mention the background knowledge about our modern calendar that you’d need for it to make any sense. Humans are good at all this, but it’s something we still haven’t had much luck teaching computers to learn, and it’s more than has ever been observed in even the smartest monkeys. And some of those monkeys can put particularly stupid humans to shame. This was seriously big news, if the horse really was that clever.

So although it was possible that nobody had looked closely enough to notice such language skills in horses before, or that Hans was some kind of prodigy, it might be something simpler. Maybe his handler was subtly signalling for the horse to tap the requisite number of times, and all the horse was doing was following simple instructions. It wouldn’t necessarily have been noticed if this was the case – people probably weren’t paying much attention to the guy just hanging around with the wonder-steed. Maybe it was all just a cruel and cynical hoax, to win the hearts and loose change of gullible audiences.

Well… not exactly. It doesn’t look like anyone ever knowingly cheated to simulate Clever Hans’ talents. Even when someone other than his handler was asking the questions, his success rate was still impressive. But it turns out they didn’t need to be cheating. Hans was picking up cues, but not intentional ones, and giving his answers solely based on the expectaions of his audience.

Remember that Hans wasn’t declaring his answer aloud, or writing down any unambiguous symbols. He would tap his foot, and again, and again, with a short pause between each time. One way to give an infallibly correct answer to any numerical question, without needing even a primitive understanding of mathematics, would be to start tapping, and somehow work out when you’re supposed to stop. If you have a captive audience eagerly watching your every move, and who do know exactly when you should stop to give the right answer to the problem, this might be possible. If you’ve asked Hans to calculate 3 + 2, your thoughts as you watch him might run along the lines of:

“Okay, let’s see if he can do this… One, two, good, you’re on the right track so far, three, still looking good, four, well done, almost there, this is a truly astonishing feat, don’t stop now… five! He’s done it! Is that it? He’s stopping there? Hurrah! This horse is a genius! Put him in charge of our country’s major financial institutions immediately!”

It seems likely that your body language and facial expression would have changed noticeably over the course of this internal dialogue, even if you didn’t do anything silly like leap to your feet applauding wildly the moment the fifth tap landed. And it seems that horses like Clever Hans can pick up on that kind of thing, and react accordingly.

What gave it away was when psychologist Oskar Pfungst, who was part of a genuine thing called the Hans Commission, checked what happened when Hans couldn’t see the person asking the questions. The success rate plummeted. When he couldn’t read the increasing tension on people’s faces as he neared the right point to stop, and the relief and relaxation that swept over them when he got there, he was just a horse tapping his foot and hoping it would be good enough to earn him another salt lick.

This is a good example of why, when establishing the validity of any claim, we need to do everything we can to be rigorously scientific about it. We’re going to end up wandering blindly down a completely fallacious route, if we don’t rule out any alternative explanation, from any source, in exactly the way that kooks and pseudoscientists and the delusioned always object to. It’s not a matter of “taking their word for it” that something’s really going on the way they describe, because even if they’re being completely honest (which a great deal of woo-merchants are), reality can always surprise you by being weird in a completely different way from how you expected. In this case, it seems that horses can infer a surprising amount of information from faces that peple don’t even know they’re making, which itself is actually pretty cool. (This curious phenomenon of subconscious non-verbal cues creeping in to provide misleading data has become known as the “Clever Hans effect”.) But there’s just no reason left to believe that the original story is true.

It’s not that Pfungst refused to be “open-minded”. He was open to the possibility of the claims about Hans being correct, but he didn’t completely and unthinkingly believe everything he was told straight away. He knew that a lot of the hype sounded unlikely, so he was also open to the idea that there might be a more mundane explanation. The bizarre and unprecedented claim was rejected, not because of “closed-mindedness”, but because of a complete lack of evidence. The evidence for the idea that horses can do sums has been stripped back to literally nothing. If we hadn’t been able to use science to do that, we’d still be stuck believing something ridiculous.

Of course, the science that blew his entire claim totally out of the water didn’t stop Wilhelm von Osten, the owner of the horse, from touring the country with him and continuing to make utterly baseless claims. This, in turn, is a good example of how retarded some people can get when they shut their basic critical faculties down in favour of not having to admit that they’ve ever been wrong.

Read Full Post »

%d bloggers like this: