3 ms·

The 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

by jaclaz 7y ago

The 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 ago
I 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.
  - lultimouomo 7y ago
    > 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". Google for "civil forfeiture dog car stop". They don't need to find drugs to take the car or any cash in it, as the dog signalling is deemed enough of a cause for forfeiting, though not for prosecuting criminally.
    - jaclaz 7y ago
      Sure, I know about that. It is part of the (IMHO completely off) ways the Law is applied in the US, I don't think that the same exists (or is used to the same extent) in other countries. But the base issue is still about reliability of the dog, the integrity of the trainer handler and how it is considered "acceptable" see: https://www.washingtonpost.com/news/the-watch/wp/2015/08/04/federal-appeals-court-drug-dog-thats-barely-more-accurate-than-a-coin-flip-is-good-enough/ https://www.washingtonpost.com/news/the-watch/wp/2015/08/04/...
      - bayesian_horse 7y ago
        Intent on the part of the handler is optional, I think. Common Biases on top of good intentions would be enough to produce the "desired" false positives.
  - cbanek 7y ago
    For less reputable police, they might just say the dog alerted when it didn't. What's a layman to say? No it didn't? And courts usually give the benefit of the doubt to police, even if they technically shouldn't. Because police don't need probable cause to use a dog to search your car means it is the de facto way to escalate to a probable cause search, and even if a dog isn't present, bringing one there usually makes people uneasy, leading to claims of "suspicious behavior", and allows the police to detain someone until it arrives. Sadly, I don't think the false positive alert rate is something the police are looking at or trying to reduce. In my cynical opinion, they are just looking for more reasons to find you a criminal, even if you aren't one. If they view you as a criminal to start, that's a huge burden to overcome.
- pulisse 7y ago
  > In many jurisdictions, including the US, police officers are not allowed to search anybody or their cars, even if they are black. In many US jurisdictions it is settled case law that a search is justified if an officer simply avers that they detect the smell of marijuana, with no other cause or corroboration required.
hnick 7y ago
I haven't read the article (it's a little late in the day for academic prose) but have done a lot of scent work with my dog as a hobby, and talked with a trainer who does it for a living (bombs, drugs, etc). Handler bearing absolutely plays a role if you aren't careful. One way our trainer taught us to fix this was to try to pull the dog away from the scent during training. If he follows us, we leave the room and stop the activity. The idea is to tell him that humans are stupid, they don't know where the scents are, so stop trusting them, because then your game and reward goes away. It worked very quickly and now he locks his legs and won't move when he's got the odour. This avoids accidentally pulling him off the odour when you're covering a large area at a brisk pace. Regardless, whenever possible one of us hides the odour and the other runs the dog. This helps us avoid any preconceptions (such as focusing on one corner of the room, missing potentional scent cones from cross-drafts). Humans can still mislead the dog like this so it's best to form good habits and have an open mind.
anonymfus 7y ago
>so at the most this influence leading to false positives will cause some time wasted That "time wasted" feels more like a psychological torture or at least a day ruined, and you ignore that cops stop mostly the same people every time, so sometimes it's a day ruined every day.
praptak 7y ago
4) Fabricating a probable cause for a search when there is none: news.ycombinator.com/item?id=10942196

by jaclaz 7y ago

bayesian_horse 7y ago

I 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.
- lultimouomo 7y ago
  > 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". Google for "civil forfeiture dog car stop". They don't need to find drugs to take the car or any cash in it, as the dog signalling is deemed enough of a cause for forfeiting, though not for prosecuting criminally.
  - jaclaz 7y ago
    Sure, I know about that. It is part of the (IMHO completely off) ways the Law is applied in the US, I don't think that the same exists (or is used to the same extent) in other countries. But the base issue is still about reliability of the dog, the integrity of the trainer handler and how it is considered "acceptable" see: https://www.washingtonpost.com/news/the-watch/wp/2015/08/04/federal-appeals-court-drug-dog-thats-barely-more-accurate-than-a-coin-flip-is-good-enough/ https://www.washingtonpost.com/news/the-watch/wp/2015/08/04/...
    - bayesian_horse 7y ago
      Intent on the part of the handler is optional, I think. Common Biases on top of good intentions would be enough to produce the "desired" false positives.
- cbanek 7y ago
  For less reputable police, they might just say the dog alerted when it didn't. What's a layman to say? No it didn't? And courts usually give the benefit of the doubt to police, even if they technically shouldn't. Because police don't need probable cause to use a dog to search your car means it is the de facto way to escalate to a probable cause search, and even if a dog isn't present, bringing one there usually makes people uneasy, leading to claims of "suspicious behavior", and allows the police to detain someone until it arrives. Sadly, I don't think the false positive alert rate is something the police are looking at or trying to reduce. In my cynical opinion, they are just looking for more reasons to find you a criminal, even if you aren't one. If they view you as a criminal to start, that's a huge burden to overcome.
pulisse 7y ago
> In many jurisdictions, including the US, police officers are not allowed to search anybody or their cars, even if they are black. In many US jurisdictions it is settled case law that a search is justified if an officer simply avers that they detect the smell of marijuana, with no other cause or corroboration required.

hnick 7y ago

I haven't read the article (it's a little late in the day for academic prose) but have done a lot of scent work with my dog as a hobby, and talked with a trainer who does it for a living (bombs, drugs, etc). Handler bearing absolutely plays a role if you aren't careful. One way our trainer taught us to fix this was to try to pull the dog away from the scent during training. If he follows us, we leave the room and stop the activity. The idea is to tell him that humans are stupid, they don't know where the scents are, so stop trusting them, because then your game and reward goes away. It worked very quickly and now he locks his legs and won't move when he's got the odour. This avoids accidentally pulling him off the odour when you're covering a large area at a brisk pace. Regardless, whenever possible one of us hides the odour and the other runs the dog. This helps us avoid any preconceptions (such as focusing on one corner of the room, missing potentional scent cones from cross-drafts). Humans can still mislead the dog like this so it's best to form good habits and have an open mind.

anonymfus 7y ago

>so at the most this influence leading to false positives will cause some time wasted That "time wasted" feels more like a psychological torture or at least a day ruined, and you ignore that cops stop mostly the same people every time, so sometimes it's a day ruined every day.

praptak 7y ago

4) Fabricating a probable cause for a search when there is none: news.ycombinator.com/item?id=10942196