Scent threshold - upper issue

[jocoyn]

Renee - you mentioned that there are now articles (I was trying to dig that out of the testimony but it was too all over the place for me) that a dog trained in low levels of a substance without proper exposure to high levels may not indicate, may not even notice, or may fringe alert on larger quantiites.

Other than common knowledge (and I acknowledgethis effect -though what I don't have is the fringe alert, but difficulty working out the scent pool) are there published and available articles on this that you know of?

[ladylaw203]

I will look for Dr. Furton's later. I also assisted in research with regard to this for Texas A and M which is soon to be published

Basically, Furton discovered what myself and some others have been preaching for years because we learned it working narcotic detector dogs. Amounts produce a different scent signature to a dog due to their scent discrimination ability. Now, do some dogs generalize better than others and work it out? Yes. I have done my own experiments with odor over 20 years because it fascinates me. I also have seen this putting on seminars for years. The dog trained on tiny amounts will most probably struggle when presented with a full set of remains above ground,shallow or in shallow water. In other words he will fringe or not go to source,but stay in the amount of odor that he is used to working.
The diversity of aids is important as well.

[jocoyn]

Would love notification on the article when it comes out! I assume you will post when it goes to press.

Looking forward to the May seminar in Culowhee at the FOREST - with another opportunity to work full body decomp.

I put the question here because I know it relates to ALL kinds of detection work, not specifically HR.

[jocoyn]

Oh, and because these forums are public. The remains, out for scientific studies, are not directly accessible to the dog but in a chain link fenced area which is also in another fenced area - I will be happy to get within 10 feet of a source this size.

What I gather is different than Knoxville is that area is way off in the woods so an actual "search" for it, can be done.

[ladylaw203]

Yes. ALL of these studies etc impact all scent detector dogs. that is why I spend so much time trying to educate civilian handlers to keep abreast of current trends in the courtroom,studies etc. We are just recently seeing cadaver dogs addressed in the courtroom and naturally,they use the narcotic dogs as a yardstick.
10 feet will be fine. also note the age of the HR.

[jocoyn]

We have been fortunate to have a few big exposures .... but I completely understand than when a body is found it has to be taped off and processed and they don't need dogs and handlers in the middle of the scene. Spectrum being another big challenge, particularly with HR.

[DFrost]

As a trainer, it's important to recognize that a threshold can shift. For example, as has been discussed, a dog encountering an unusually large amount of odor can have trouble responding. After having been exposed to that large amount of odor, one must also recognize a dog would have trouble detecting a smaller odor for a period of time after encountering the larger odor. That is "threshold shift". A dog determines "source" by looking for the next higher concentration. when the dog has reached a point of saturation, it can no longer detect a weaker or stronger odor. At that point, the dog is stymied and must be removed from the situation until it (the dog) returns to normal. I think the military did a great job of teaching this with the odor spectrum.

DFrost

[ladylaw203]

Originally Posted by jocoyn

Oh, and because these forums are public. The remains, out for scientific studies, are not directly accessible to the dog but in a chain link fenced area which is also in another fenced area - I will be happy to get within 10 feet of a source this size.

What I gather is different than Knoxville is that area is way off in the woods so an actual "search" for it, can be done.

my understanding is that the area is about the size of a small backyard there.

I would not reward my dog at the fence due to the fact that one would be rewarding for a final trained response NOT at source. I would praise and take the dog to another source that I could reward at source. Just something to ponder

[ladylaw203]

Originally Posted by DFrost

As a trainer, it's important to recognize that a threshold can shift. For example, as has been discussed, a dog encountering an unusually large amount of odor can have trouble responding. After having been exposed to that large amount of odor, one must also recognize a dog would have trouble detecting a smaller odor for a period of time after encountering the larger odor.
DFrost

Exactly. Problem is that many cadaver dog handlers do not have realistic amounts of HR to train on so their dog's thresholds are low. They fringe when presented with a realistic amount . I see a lot of dogs fringing in shallow water search because of that for example. hard for them to get training aids and many do not understand the threshold issue and realize what their dog might be doing.

[jocoyn]

We did learn a way around the fringing issue when you have a breeze ..... work those with the wind at your back helps a lot with pinpointing.