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The Dog Zombie
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- June 2, 2010
- 04:17 PM
- 516 views
The assessment of emotional expression in dogs
by The Dog Zombie in The Dog Zombie
“The assessment of emotional expression in dogs using a Free Choice Profiling methodology” (Walker et. al., Animal Welfare).Do different people tend to have overlapping or at least complementary ways of describing dog behaviors? And if they do, can a computer put together a behavior scale out of those descriptions, even without any understanding of what’s actually being described? Put a different way: Can we describe a group of observations of dog behavior using a fancy statistical technique which is hard for Dog Zombies to understand? Our intrepid investigators put a bunch of college women together with some dog videos and applied a lot of statistical processing to find out.The mammalsThe people: eighteen undergraduate women with varying levels of familiarity with dogs, but all currently studying animal behavior. (At a guess, they were all students in a class taught by one of the investigators.)The dogs: ten Beagles trained as customs dogs.The setup: The 18 women sit in a movie theater. They watch video clips of the beagles. They write down words that come to mind as useful in describing the dogs.At the end of this first session, they hand in their terms. They then are sat down again (it doesn’t say if they’re all together in the movie theater this time, but I imagine them at individual desks for some reason) with the list of terms that they had generated. Each person gets their own list; there’s no collation yet at this point. They watch some of the beagle videos again. (I sympathize. I have watched a lot of Dog TV lately.) They rate each dog against each term using a visual analog scale. That’s a line, from zero to lots, and you put a mark on the line to rate the dog.So if I were to have the word “zonked,” and be asked to rate my dog Jack at this moment, I’d draw a line and put a mark on it to rate how far along the “zonked” scale he is. Jack is currently fully lateral on the floor and twitching, so I’d put the mark on the far left of the scale. If you then asked me to rate him for “cute,” I’d put the mark on the far right. For “red,” I’d put the mark somewhere in the middle, based on my personal assessment of how red he is on the scale of blond to brick. (Jack’s sort of a strawberry blond, so the marker would be a little left of center.) So these are very individual sorts of assessments.The computersThe investigators then took all this data and turned it into numbers by measuring the distance of the marks in terms of millimeters. And they handed it to a computer, which performed Generalized Procrustes Analysis (GPA) on it. I love that this technique involves the name “Procrustes.”So, this is where I sort of want a companion blogger who is an expert in statistics to take over for a few paragraphs. I am not an expert in statistics by any means, but I will give explaining what happens next a shot. Please take it all with a grain of salt; I may be completely inaccurate.Basically, I imagine the computer spreading all these scores out and seeing which ones match. I think the idea is, if one dog gets a 3-4 mm score by lots of observers, then the computer guesses that those people are all measuring the same thing with those particular terms. The computer checks to see if other dogs also rank similarly with those terms. So if one dog scores 1-2 mm on Term 2 from Observer 5, and Term 3 from Observer 7, then Observer 5’s Term 2 might be describing the same thing as Observer 7’s Term 3. It would then be worth checking a second dog. Is its score on Observer 5’s Term 2 (say 4.4 mm) similar to its score on Term 3 from Observer 7 (say 4.6 mm)? If so, and if other dogs are also similar, those two terms might be describing the same thing (“nervous” vs “shy,” for example).In addition to seeing which terms might be measuring the same thing, the computer is also trying to figure out which terms are related to each other in other ways. If this dog scores high on Term 1 from Observer 13, does he also score low on Term 3 from Observer 13? Maybe those terms are opposites. (“Outgoing” vs “shy,” for example.) If this dog scores very high on Term 2 from Observer 10, does he also score mid-range to high on Term 7 from Observer 12? Maybe those terms have some sort of relationship, but aren’t exactly the same thing (“outgoing” vs “friendly,” for example).From all this, the computer comes up with “dimensions.” Although the eighteen women had just ranked each dog in terms of “how much of this term does it have?”, the dimensions are paired, so that a group of positive terms are at one end, and a group of negative (opposite) terms are at the other. In this case, they got three dimensions:playful/happy/confident versus nervous/unsure/tensealert/inquisitive/investigative versus attention-seeking/quiet/unsureplayful/nervous/boisterous versus calm/relaxed/confidentSo each of the observers’ original terms were allocated to one (or more?) of these dimensions. “GPA thus transforms the 18 different dog-scoring configurations into one multidimensional consensus profile, entirely independently of any interpretation by the experimenter.” In other words, a computer has done all the assignments, and it does not understand what the terms mean. The assignments were done in the complete absence of semantics. There is a point in the process where a check for “satisfactory semantic convergence between observer word charts” is done, checking to see if the grouped terms are reasonable concepts to put together. It’s not clear if a computer or a human performs that check. (How would a computer do it? Using a digital thesaurus? I love the idea of a database with weights for how similar each English word is to every other English word.)They assure us that the eighteen observers, when their terms are applied to this scale, score the dogs very similarly. I started to lose the thread of the statistics at this point, but they did helpfully provide an image of a bullseye. Thirteen of the observers were inside the bullseye (scored dogs similarly). Five were outside.The meaningSo what have they actually done here? It looks like these observers tended to pick up on similar traits. So if you show a dog to a bunch of people, they will have similar ideas about it. They may use different words, but whether they say “nervous” or “shy,” they will have comparable amounts of that trait in mind. And that is really interesting.Of course, I also want to say what this is not. These people may all agree about how shy a dog is, but that doesn’t mean that they are any good at telling if the dog actually is shy. The scale generated here, and the scores these observers made, has not been tested for its predictive power. I would love to see something like a test of the scale on dogs placed in new and strange surroundings. Can a dog’s score on this scale predict how it will respond to a friendly stranger, or how much it will explore versus hide in a strange room? I am not criticizing this technique; it doesn’t claim to answer that question. But I think it’s worth keeping in mind what its limits are.It does claim to tell us whether different people have similar perceptions, and I would love to see it tested on people of different cultural backgrounds, especially people who speak different native languages. The terms that the observers chose didn’t have to be the same in order to be grouped together, but they seemed to all choose similar concepts. Would people who were the native speakers of a variety of languages have such a strong overlap of chosen concepts?And, as the researchers point out, the observers were all women. Is it possible that women tend to have similar perceptions about dogs, versus the perceptions men tend to have? Do women assign different levels of importance to different behavioral traits, and are they therefore more likely to choose different traits as important enough to score?Looking more closely at the dimensions that were constructed causes me to suspect that the dimensions are indeed pulling together different traits. For example, one dimension has “alert/inquisitive/investigative” vs “attention-seeking/quiet/unsure.” Outgoing dogs on one side, insecure dogs on the other — makes sense. But the insecure dogs are also “attention-seeking.” That makes sense logically, as insecure dogs may be more likely to seek reassurance from humans. However, it is a somewhat different trait than “quiet.” In fact, I can imagine that a quiet dog might tend to be less attention-seeking, by virtue of being, well, quiet. So it’s interesting that these traits were pulled together into one dimension, even when people who labeled dogs “quiet” probably didn’t necessarily think of those same dogs as “attention-seeking.” Different behaviors, but one interpretation that pulls them together.On the other hand, you get the “playful/nervous/boisterous” dimension. That may well be different characterizations of the same trait — high energy. Some people think high energy is good (playfulness) and some think it’s less good (boisterousness, what we call “freshness” in this house). But it’s the same thing, whether it’s som... Read more »
J Walker, A Dale, N Waran, N Clarke, M Farnworth, & F Wemelsfelder. (2010) The assessment of emotional expression in dogs using a Free Choice Profiling methodology . Animal Welfare, 75-84. info:/
- March 17, 2010
- 09:55 AM
- 493 views
Nest making, oxytocin, and social bonding
by The Dog Zombie in The Dog Zombie
I encountered Nest making and oxytocin comparably promote wound healing in isolation reared rats [1] while reading about how stress affects wound healing, and it drew me in with its lure of drawing connections between nest making and oxytocin. Oxytocin does a lot of things in the body, but what this paper was interested in was its participation in social bonding. You all must already know the coolest story about oxytocin, the story about the two species of voles. The species are almost identical. One species mates for life, one doesn’t. The one that does has more receptors in its brain for oxytocin than the one that doesn’t.[2]Because of the promise of learning more about oxytocin, I chose this paper for my second and final journal club presentation. The second time is a lot less scary than the first, I learned, and preparation goes faster.This paper took a while to get to oxytocin, so let me start at the beginning. The authors had run three separate experiments which the paper covered. In the first study, Assessment of wound healing due to Nestlet treatment, they gave some rats a burn on their backs. (It was a pretty serious burn; two of the rat pups died of shock after receiving it.) Then they put them into three groups. One group of rats lived in sets of three (“group housed”). One group of rats lived alone (“isolation housed”). And one group of rats lived alone, but were given Nestlets, which are little cotton squares which can be used to make nests. They compared the healing rates of the three groups. The group housed rats healed the fastest; the isolation housed rats which had Nestlets to use to make nests healed almost as fast (statistically there was no significant difference); and the isolation housed rats without Nestlets healed most slowly.They asked themselves: why does nest making help rats heal better? It seems like the mechanism has to be central (in the brain, rather than in the rest of the body), since a nest is really environmental enrichment. In their second experiment, Time series analysis of wound healing and comparison of wound healing with Nestlets to wound healing with oxytocin, they repeated their first experiment, but this time with a fourth group of rats: isolation housed rats who were injected with oxytocin once a day for several weeks. Why oxytocin? The idea seemed to be that rats build nests together, and if a rat lives alone, building a nest is still somehow a social act. Since oxytocin is released during social bonding, a dose of oxytocin might theoretically substitute for having other rats around or for nest building. And indeed, the rats given oxytocin healed faster, with rates similar to the rates of rats given Nestlets.Finally, in Assessment of behavior and brain changes due to Nestlet administration, they had four groups of rats: group housed rats without Nestlets; group housed rats with Nestlets; isolation housed rats with Nestlets; isolation housed rats without Nestlets. No rats were burned in this experiment. They demonstrated gene expression changes (mRNA changes) in the brains of rats given Nestlets, and demonstrated behavior changes (decreased hyperactivity in an “open field test”).They conclude by suggesting that Nestlets do affect wound healing rates; these changes seem to happen because of changes in the brain (though that isn’t proven); and this particular model of wound healing and Nestlet administration might be a good model for studying stress impairment of physical health in humans.I had gone into this paper enthusiastically, because oxytocin is probably my favorite hormone. I came out the other end bothered on several levels, but decided to present the paper at journal club anyways, because it seemed like a good exercise. The attendees seemed as bothered by the paper as I was, and contributed more issues with it than those I’d come up with; actually, the presentation felt really enjoyable to me as a result.What bothered me? To start, why were the rats not given any analgesics at all? Perhaps the researchers felt that pain killers would have confounded their study design in some way, but I would have been interested to know what way. As it stood, I wondered if they simply hadn’t thought of it.Can you really say that the effects of nest making are centrally mediated (take place in the brain) just because they are similar to the effects of oxytocin? Can you even say that the effects of nest making are related to the effects of social interactions? No, you cannot. Perhaps the tool used here for measuring rate changes in wound healing was so insensitive that any number of changes would look similar. Perhaps the changes were in fact very similar but caused by very different things. (One possibility proposed by someone at journal club: the rats which were able to nest improved because the nests helped them keep warm better, something which group housed rats use each other to do.) To their credit, the authors of this paper did state that they hadn’t proven that the effects of Nestlets were centrally mediated or even related to the effects of oxytocin administration. But if they knew that their study wasn’t going to answer that question, why include the oxytocin group at all? Or, if they really were interested in comparing the two mechanisms, why not include an oxytocin group in the experiment in which they looked at behavior changes and mRNA changes in the brain?The studies certainly did demonstrate that oxytocin administration improves wound healing in isolation reared rats. But does this have to do with the fact that oxytocin is associated with bonding? It might have been interesting to see if oxytocin administration improved wound healing in group housed rats as well.The studies also demonstrated that providing Nestlets does improve healing rates in isolation housed rats. However, one rat researcher at journal club pointed out that, in fact, they couldn’t even say that “nest building” caused the improvement. Perhaps it was just the exercise of moving the Nestlets around the cage. She suggested a control group which was given exercise wheels.The suggestion that this model could be useful to study the physical effects of stress in humans gave me pause, as well. Different kinds of stress have different effects. This kind of social isolation stress isn’t necessarily going to affect a human the same way some other kind of stress might, like job-related stress. In fact, one journal club attendee pointed out that the slower wound healing rates in the isolation housed rats might have less to do with social isolation stress, and more to do with the fact that group housed rats are able to lick each other’s wounds. (None of us knew if rats actually did that, though.)As a veterinary student, I was also a little saddened by the fact that this paper was never placed by its authors into the context of laboratory animal medicine. Though the purpose of the paper was to illustrate a model that is useful for human medicine, I felt at least a sentence could have been devoted to explaining the context of enrichment for laboratory animals and why it is important.At the end of the paper, the authors explained some future directions for their research, including giving oxytocin antagonists to rats with Nestlets. This would prevent oxytocin from acting in those rats. If the effects of the Nestlets were blocked in those rats (i.e., if their wound healing slowed), then we might conclude that oxytocin had something to do with the mechanism of Nestlets’ effects. That would be an interesting next step and would definitely clarify the Nestlet/oxytocin relationship, if there is one. I wish that they had waited to publish this paper until they could include those findings; as it is, the paper felt somewhat incomplete.We talked a little bit about the journal that this paper was published in: PLoS ONE, an open access journal. One attendee felt that open access journals are likely to publish lower quality papers. I hope that’s not actually true, since I believe open access to be important. If this paper weren’t open access, I wouldn’t be able to provide a link to its full text in this blog post!Of course, the paper did have some interesting things to say. Nest making improves wound healing in socially isolated rats. That’s interesting! (But we don’t really have any idea why it does this, at least not based on this paper.) Oxytocin also improves wound healing in socially isolated rats, which I find even more interesting. I’m curious whether oxytocin has been used in wound healing experiments in the past. I know that research has suggested in the past that happily bonded people are healthier (though I don’t know anything about this field and therefore hesitate to try to find a reference for this assertion — if you have a good one, let us know in the comments). I’ve always wondered why. Do people living alone find taking care of themselves harder? They might be more likely to have trouble getting to the hospital, or lack caretakers when they’re ill, or just lack someone to tell them “You’re sick, go to bed.” This study suggests that loneliness might actually affect health more directly. Of course, the complete social isolation these rats experienced might have different effects from the milder isolation of someone who lives alone but works in an office. And healing from burn wounds is not the same thing as general health. It’s still food for thought.I was definitely dissatisfied with this paper, but the presentation was fun. The attendees felt engaged and interested. I hadn’t realized before how useful it can be to present a paper that you have som... Read more »
Vitalo A, Fricchione J, Casali M, Berdichevsky Y, Hoge EA, Rauch SL, Berthiaume F, Yarmush ML, Benson H, Fricchione GL.... (2009) Nest making and oxytocin comparably promote wound healing in isolation reared rats. PloS one, 4(5). PMID: 19436750
Young, L. (1998) Neuroendocrine bases of monogamy. Trends in Neurosciences, 21(2), 71-75. DOI: 10.1016/S0166-2236(97)01167-3
- October 20, 2010
- 07:48 AM
- 403 views
Number Needed to Ban: a new tool for calculating the benefits of banning particular dog breeds
by The Dog Zombie in The Dog Zombie
A study published this month in the Journal of the American Veterinary Association (JAVMA) takes on the issue of whether breed-specific legislation (BSL) is effective. BSL is a tool used by some communities to attempt to reduce injuries from dog bites. The idea is that particular breeds of dogs are responsible for more than their share of injuries, so banning or otherwise controlling those breeds will result in a reduction in injuries. The group of breeds collectively known as “pit bulls” receive the most attention today, though other breeds (Rottweilers, Dobermans, German Shepherds) have received attention in the past.But does BSL actually work? Experts say no; how the dog is trained and managed is a better predictor of aggression than its breed. Nevertheless, new BSL continues to be enacted. So why do legislators reach for this tool?The authors of “Use of a number-needed-to-ban calculation to illustrate limitations of breed-specific legislation in increasing the risk of dog bite-related injury” believe that BSL’s appeal comes from:Misperception of risk. Poor reporting of the number of dog bites that occur and of their severity makes it very difficult for the public to get a handle on how often they occur.Stereotyping and misinformation. The media may portray particular breeds as especially aggressive, in the face of scientific studies which suggest that they are not.Erroneous beliefs about efficacy of BSL. There is currently no evidence for the effectiveness of BSL, but there is evidence to suggest that it is ineffective.The authors hope to provide a tool for use in understanding the effectiveness of BSL, and they hijack some terminology from the medical community to do so. “Number needed to treat” (NNT) is a concept used to understand the effectiveness of a particular medication or therapy. For example, you have a patient showing signs of a stroke. Should you give him tPA (tissue plasminogen activator)? One measure you might use in making this decision is NNT. How many similar patients would you treat with tPA, on average, before you saw one patient improve? A smaller NNT implies a more effective therapy. In human medicine, we expect the NNT of an effective therapy to be in the tens or at most hundreds.The authors suggested evaluating BSL’s effectiveness using a “number needed to ban” (NNB) concept. If BSL is implemented in a particular community, how many dogs will need to be banned (removed from the community) before one dog bite (or dog bite related injury, or dog bite related fatality) is prevented?The authors point out that because our knowledge of the true prevalence of dog bites is so poor (many are never reported), this calculation is hard to do. I think the important thing to understand is that what they are offering is a tool that can be applied to different statistics. After all, dog bite prevalence will vary among different communities. This tool can be used to understand the possible benefit of BSL in different communities. It’s an algorithm to apply to a variety of data inputs!However, the paper would have been really unsatisfying without some numbers, so they applied their algorithm to some statistics (much appreciated, because I hate arithmetic).Based on the reported number of dog bite related emergency department visits, 5,128 dogs would have to be banned to prevent a single emergency department visit in one year.In Kansas City, 4,255 dogs would have to be banned to prevent a single emergency department visit in one year.30,663 dogs would need to be banned to prevent a single reconstructive surgery in one year.109,495 dogs would need to be banned to prevent a single hospitalization in one year.59,523 dogs would need to be banned to prevent a single insurance claim in one year.The authors note that these calculations were based on legislation banning a particular breed or breeds entirely. For legislation which simply requires that dogs of a particular breed(s) be muzzled while in public, these numbers would be even higher, because such legislation would not prevent bites on private property (which is where many of them occur).It is the authors’ hope that “easily understood communication tools, such as NNB, can help put the lack of efficacy of BSL into perspective and narrow the perception gap.” This is a great tool and I hope we see it used more. I am concerned that proponents of BSL will argue that any tool is only as good as the data put in to it, and that the lack of reliable reporting of dog bites will mean that this tool isn’t itself reliable. However, as long as we are focusing on enacting BSL instead of focusing on understanding the true problem, our data will continue to be flawed. This article represents a step forward in understanding data about the causes of dog bites. Our next step is improving the accuracy of that data.Patronek GJ, Slater M, & Marder A (2010). Use of a number-needed-to-ban calculation to illustrate limitations of breed-specific legislation in decreasing the risk of dog bite-related injury. Journal of the American Veterinary Medical Association, 237 (7), 788-92 PMID: 20919843... Read more »
Patronek GJ, Slater M, & Marder A. (2010) Use of a number-needed-to-ban calculation to illustrate limitations of breed-specific legislation in decreasing the risk of dog bite-related injury. Journal of the American Veterinary Medical Association, 237(7), 788-92. PMID: 20919843
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