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Handler beliefs affect scent detection dog outcomes (2011)
- tiku 7y agoWell it is not far fetched that they can smell the excitement or anxiety of their owners as they approach the evidence they believe is the correct one?
- anon9001 7y ago> For scent detection dog handlers, beliefs that scent is present might result in either sufficient inadvertent postural and facial cues so that dogs will respond regardless of the absence of scent I don't know how good dogs are at pose detection, but it's definitely plausible that they can tell when an alert is expected.
- bayesian_horse 7y agoA less subtle cue would be how they treat the "suspect". It's less about the handler's pheromones and more about movement, speech and posture.
- taneq 7y agoThey can probably smell their handler getting interested well before the handler's consciously even aware of it.
- bayesian_horse 7y agoI doubt that, at least in the literal sense of smelling. Dogs can however distinguish behavior patterns in their handlers, because that's mainly how they get rewards and are punished. Both the patterns and the rewards are much more subtle than handlers are generally aware of. A service dog is in some sense the worst case of an overfitting machine learning model you can imagine.
- katakuchi 7y agoI only read an excerpt of the article, but it seems to me that it might be tough to attribute the false detection to a certain variable within the animal's cognition. Is it perception of human behavior, mental state, tone of voice, owner's scent or maybe even some Pavlov effect on picking out cases that are certainly positive? However, this obviously has some interesting implications in court cases or situations where a traveller might be falsely accused of drug traffic, or when suspect X is 'randomly' selected for checks.
- praptak 7y agoI've heard this mentioned a few years ago in a TV report on dogs used in labs that test evidence for criminal trials. Their procedure was to let the dog alone into a special scent-free room that contained the sample being tested, plus a few control ones. The samples were placed into containers that only let the smell out (no visual cues, even though the samples were identical-looking cotton swabs). Also, I vaguely remember a high-profile case where the evidence was dismissed precisely because the procedures for gathering and testing the samples were not followed.
- jaclaz 7y agoThe observation seems logical, but I wonder what is actually the relevance of the study in practice. I mean, there are three common situations where these dogs are used: 1) airports, stations, traffic stops etc. where the influence of the trainer might be relevant (i.e. the trainer, even if involuntarily, may influence the dog if the person that is sniffed - or their belongings/looks/behaviours/etc. - look suspicuous to the trainer) 2) search in buildings for drugs or explosives 3) screening of mail, packages, containers, etc. I believe that among these only in activity #1 the trainer might have some pre-constituted suspect that would "trigger" the influence on the dog. But in any case the dogs are only used as a means of "triage" of sorts, so at the most this influence leading to false positives will cause some time wasted. Still in case #1 (and possibly in case #3) the issue might be that if there are too many of these false positives, while the attention of the trainers/policemen is drawn to the "false target" some other one (actually carrying drugs or explosives) will "go through".
- bayesian_horse 7y agoI have heard the term "search warrant on four legs". In many jurisdictions, including the US, police officers are not allowed to search anybody or their cars, even if they are black. So if the dog learns to please his handler by indicating contraband, they have a chance to at best inconvenience anyone they (dis)like.
- jaclaz 7y ago>So if the dog learns to please his handler by indicating contraband, they have a chance to at best inconvenience anyone they (dis)like. Sure, but (of course it depends on countries and local Laws) it is only one of the possible ways (excuses) that can be used to target someone. Of course if in the car there is no drugs (or explosives) the only net result is a waste of time of both the policemen and the "target". It would seem to me much more relevant to know how many cars searched after a dog sniffed something ended up as being actually contraband free (false positives) and how many actually turned out as actually containing some drugs or whatever. If the dogs (in experiments without the influence of the trainer) have an accuracy of - say - 90% and with the influence of the trainer (or whatever other reason causes on field differences) this drops to - still say - 55% then there will be an issue as we would be nearing the flipism convenience, but if the overall accuracy remains in the 80 or 85% range then the effect - even if noticeable - would be not much relevant in practice. Or, if you prefer, I completely agree that a trainer can induce a dog to sniff something even when there isn't any, but the relevance of the fact depends only on how often this happens.
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- truths33k3r 7y agohow is this nonsense even getting published? tiny sample size, n=18 dogs 5 different breeds of dogs large variance of dog age
- ShlomoS 7y agoThe sample size is adequate for the conclusions drawn from the results. The breeds and ages are representative of dogs used for this work. Nothing in your post supports the idea that the study is "nonsense".
- your-nanny 7y agoif the dogs were restricted to male Labradors age 5, then the range of inference would be male Labs age 5.
- BlackFly 7y agoThis shouldn't surprise you, but if the effect is large and real, you don't need large sample sizes to prove something. As an example, a loaded die that always comes up with 6. After 18 straight 6's in a row, you are more than assured that you have a loaded die. I imagine that a rational person is convinced long before the 18th 6. The point is: large samples are only needed to measure small effects. Most studies nowadays need large samples because the large effects are low hanging fruit and were noticed quickly (in the past). Meanwhile, finding a single black swan proves that not all swans are white. This study proves that in even a small selection of scent dogs, you are going to have dogs which are highly affected by handler signals. You might be able to use the methods of the paper to exclude dogs which pick up on handler signals and therefore improve the training regimen of scent dogs, there is no evidence to support this possibility however.
- ptah 7y agodoes this imply that the dogs perform a similar role to dowsing rods in this situation?
- 693471 7y agoThis is the analogy I've been looking for.
- seanwilson 7y agoIs this not fairly well understood? e.g. https://en.wikipedia.org/wiki/Clever_Hans https://en.wikipedia.org/wiki/Clever_Hans > Clever Hans (in German: der Kluge Hans) was an Orlov Trotter horse that was claimed to have performed arithmetic and other intellectual tasks. > After a formal investigation in 1907, psychologist Oskar Pfungst demonstrated that the horse was not actually performing these mental tasks, but was watching the reactions of his trainer. He discovered this artifact in the research methodology, wherein the horse was responding directly to involuntary cues in the body language of the human trainer, who had the faculties to solve each problem. The trainer was entirely unaware that he was providing such cues.
- kenny_r 7y agoThis particular horse is mentioned in the very first sentence of the introduction of the paper. I think it's a worthwhile study, especially considering such dogs are currently still used in law enforcement. It's important to be aware of the shortcomings and biases of this methodology, and to do so in a sound, scientific manner.
- edoo 7y agoIt should be easy to train the dogs in an environment where the trainer does not know the intended result and must investigate each claim from the dog. All the dog training vids I've seen have the trainer themselves knowing exactly what lies in the course.
- silveroriole 7y agoI don’t think this would be easy. For training, the reward needs to come as quickly after/during the action as possible. Most dogs don’t have a great mental capacity for figuring out that they’re being rewarded for something that isn’t happening right now. If the dog has to wait even 10 seconds for the trainer to figure out whether to reward or not, a lot of dogs are going to get confused.
- logfromblammo 7y agoDuring training/testing a second person, who is not visible, audible, or smellable to the dog, and who knows the conditions of the course, observes the pair via cameras and microphones. When the dog hits on something, the observer presses a button, indicating which target or decoy was indicated, or that an unexpected other object was indicated. The observer may also indicate when the dog seems distracted, or especially attentive to the handler. A computer takes the buttons as inputs, and if its intermittent reinforcement program indicates it, the handler receives an instruction to reward the dog. The program may also reward the dog for misses, or just for paying attention to handler instructions, so the handler is not able to associate rewards with accurate hits. The handler then still has to investigate the hit to determine what the dog found.
- the-dude 7y agoUp to 2006 'scent identification' ( linking persons to objects ) was used as evidence in Dutch courts. It turned out the test weren't done 'blind' and the practice has been abolished.
- daddylonglegs 7y agoDogs are very good at reading people and if the handler wants an indication they will get it; they may not even realise that they're influencing the dogs. As others have said, this has been known for a long, long time. There was even a book written taking a wry look a scent dogs (and the plans for scent bees etc that were in vogue during the great war on terror) [1]. That said, dogs can be fantastic when used for finding threats rather than 'proving' what the handler already believes. They have a combination of nose and brain that we can't replicate any other way and are great for search and rescue, finding explosives and some law enforcement searching. [1] https://headspace-the-book.blogspot.com/2008/07/acpo-police-dog-training-and-care.html https://headspace-the-book.blogspot.com/2008/07/acpo-police-...
- sneak 7y ago...and yet dog alerts (encapsulating handler biases) alone are still used to establish probable cause in the US to strip people of their rights to privacy, and has resulted in jail for thousands of people who do not deserve it.
- dymk 7y agoIt's better than absolutely no preventative measures at all
- ksdale 7y agoThat's very debatable. I, personally, would much rather that people in possession of drugs go free rather than the police using the dogs as an excuse to search people they don't like the look of.
- Smithalicious 7y agoYes, but I suspect you would also support lighter sentencing or even decriminalization of drugs. I don't think you'd think the same if it was concerned potential terrorists or child sexual abusers. Basically, this kind of comment usually encodes some belief on what the law should be rather than a belief about how it should be enforced. And that's just not the issue at hand here.
- your-nanny 7y agoI think the more likely explanation is that the handler's sensitivity to dog alerts changes with handler's beliefs, a possibility they raise in the paper's discussion.
- praptak 7y agoIn this context it is ridiculous that a dog test is considered a probable cause for a police search: news.ycombinator.com/item?id=10942196
- Smithalicious 7y agoIs it really? Probable cause doesn't need to be a high bar, in my opinion. Contrary to what people here seem to think, I don't think a police search is that invasive and I'd rather we perhaps search some people on shaky grounds than we let people with drugs/bombs/whatever walk free.
- htek 7y agoSo you're cool with a cop that is biased against black people using their dog as a pretense to search them? Oh, and, yes, a police search is invasive and demeaning. I suggest you try it before you discount it.
- Smithalicious 7y agoNo I do not support people doing bad things. That does not mean that I am against everything that could possibly be used for evil. This is an absolutely inane accusation. Are you fine with black communities being ruined by crack cocaine because police can't search people? Of course not, that'd be a ridiculous thing to think.
- htek 7y agoWhat you're saying is that it's okay to treat all black people as if they're criminals because a small subset of them engage in criminal activity. It is well established that black and white people use illegal drugs at about the same rate. Where's the call for stop-and-frisk of all white people? Or doesn't that fit your think-of-the-black-community veil over your racism?
- praptak 7y agoThen just do away with 4th amendment, rather than pretending that cops respect it.
- tanepiper 7y agoI've been doing detection classes with our Polish Hunting Spaniel and she's quite the natural, but the hardest part of it is training the human (i.e. me) to NOT give off any queues about where I think things may be. Of course, these are fun classes and in no way controlled environments - but the best thing you can do is to trust the dog's judgement.
- corodra 7y ago18 dog teams? What a thorough experiment. Sounds like the infamous chocolate weight loss study that was pushed to the media that made them look stupid. To a small degree I can agree to this. But I have k9 officer friends and I know their dogs. Good luck with this. It means a bad and impatient handler rather than an ineffective dog. But it's alright, police baaaaad. Evidence is evil.
- mgarfias 7y agowould have been better to use SAR dogs.