The Cognitive Dog

1. The Cognitive Dog • Class 11: A little bit about statistics and alot about cue use

2. Agenda • Looking ahead • Statistics in 15 minutes • What we know about the use of gestures by dogs to guide their choice

3. Looking ahead...

4. The big picture • Do pet dogs use human cues (gestures, gaze, body position, motion, voice) to guide their behavior? • Well, do they? • If so, to what feature are they attending? • Why are they using the feature? • What mental representation do they build, i.e., is it a ‘simple’ association or do they understand the meaning of the cue at some ‘deeper’ level. • What larger story does this tell?

5. The big picture continued... • The larger story... • Is it a difference in underlying ability, or in performance? • Are the observed differences, side-effects of changes in other behavioral systems, or were they directly selected for, i.e. a social cognition gene? • If the differences are due, in part, to genetic differences, what is the nature of those differences? • And how do we discover this?

6. The cognitive tasks we are going to examine • Use of pointing gestures (this week) • Object Permanence, Invisible Displacement, Means-Ends (next week) • Social Learning (week we get back) • Use of acoustic cues (words...) • The big theme... • Dogs are masters of using simple but reliable rules to make sense of a complicated world, so indeed, they may be doing just enough to get by.

7. But first, statistics in 15 minutes...

8. “If your experiment needs statistics you ought to have done a better experiment...” -Lord Rutherford

9. Characterizing data... • I am the marketing manager of “Destruct-Not” chew toys and I want to say something about how long they last. So I probably need... • Some measure of the average or mean time that they last: also known as the mean, e.g. 10 minutes. • Some measure of the spread or variation around the mean, e.g., for some dogs they last 1 minute, for other dogs they last 15 minutes, for most dogs they last between 8 and 11 minutes.

10. Variance and standard deviation measure spread

11. Hinton, P. R. (2004). Statistics Explained. London, UK, Routledge. The normal distribution characterizes how values tend to be distributed around the mean, and also the probability of observing a given value given that distribution The normal distribution

12. Hinton, P. R. (2004). Statistics Explained. London, UK, Routledge. Hypothesis testing • is the probability of observing a given value likely given what you know about the population

13. Significance... • Significance is a statistical term that indicates the level of confidence in rejecting the null hypothesis, or that you are seeing a real effect. BUT, just because you are seeing a real effect does not mean that it is an important effect, e.g., • Choosing 51/100 may be statistically significant from 50/100, but in the grand scheme of things, it may not be important. • When you see p <.01, that is to be read as “There is a 1% chance of seeing this result if the null hypothesis is true.”

14. Example • Known distribution: length of time required to destroy current “Destruct-Not” chew toy. • Null hypothesis: new and improved “Destruct-Not” chew toy is no better than old toy. • Test and see where results lie relative to ‘known’ distribution • Accept or reject null hypothesis Hinton, P. R. (2004). Statistics Explained. London, UK, Routledge.

15. Samples vs. Population • Population: complete set, e.g., all dogs that use “Destruct-Not” chew toys • Sample: a subset of the population. • To be useful, a sample needs to be a ‘representative’ subset of the population. Questions to ask? • How big does the subset need to be? • How do you choose members to be in that subset? • How do you test?

16. Sample size and the pooling fallacy... • Intuitively, the bigger the sample size, the more representative your sample will be: by representative, I mean it has a mean and variance that accurately reflects the population. • But it needs to be the right kind of bigger. Which sample will be more representative... • Test 10 different dogs each of a different breed & measure how long it takes them to destroy a new “Destruct-Not” toy. • Test 10 different dogs from “toothless terrier manor” & measure how long it takes them to destroy a new “Destruct-Not” toy. • Test “Chomper” 10 times & measure how long it takes him each time to destroy a new “Destruct-Not” toy.

17. The T-statistic 99% Confidence, 20 samples 99% Confidence, 5 samples • In practice, you don’t know what the population standard deviation is, so you need to estimate it using your sample. • That estimate of the standard deviation needs to be adjusted to reflect that it is based on a certain number of samples • The t-statistic corrects for this. • e.g., T(9.77) = 7, P<0.001 Pooling artificially makes the standard deviation smaller, so you are more likely to see a “significant” result

18. You see the pooling fallacy in almost every experiment of dog cognition!!!!!! • To increase the sample size the experimenters test the same dog multiple times and treat each time as an independent measurement... • But it isn’t an independent measurement because it is the same dog doing it. • 10 dogs each doing the point test 10 times should be considered 10 samples, not 100. The average for each dog should be considered a sample. • The practical effect of the pooling fallacy is that it makes the spread smaller than it may be in reality, and make it more likely to reject the null hypothesis, e.g. rejecting the hypothesis that the dog is responding at chance levels.

19. More things to think about regarding a representative sample... • What is the criteria for choosing dogs? • What is the setting in which you test the dogs: home, dog-park, vet’s office, lab-setting...? • What is the criteria for measuring the time? • When do you start timing? • When do you stop timing: what is the criteria for “destroyed” • Is the criteria objective, or does it rely on the judgement of the tester?

20. Even more things to think about... • Is your test • Reliable • Accurate • If testing the same dog multiple times, is there a learning effect? http://en.wikipedia.org/wiki/Accuracy_and_precision

21. Coming to the wrong conclusion... Is it new and improved? • Type 1 error: being fooled by an ‘outlier’ into rejecting the null hypothesis (rejecting green point) • Type 2 error: being fooled by a point that is consistent with null hypothesis into accepting it (accepting purple point.) • Reducing one type of error tends to increase other. Hinton, P. R. (2004). Statistics Explained. London, UK, Routledge. Avg. minutes before total distruction for new and improved ‘Destruct-Not’ toy Sample 1 Sample 2

22. The take-home message... • Lord Rutherford had a point... • Pay attention to the details of the experiment. Those are the things that you as a dog person can evaluate: how were subjects selected, are there things in the experimental set-up that might have affected the animal’s performance, are there alternative explanations, what was the experimenter’s bias and did they control for it, what is the rule of motivation/learning/emotion in shaping the dog’s response. • If you care, get someone who understands statistics to read over the paper. Even peer-reviewed journal articles contain flaws in statistical analysis.

23. Dogs use of pointing gestures...

24. Hare, B. and M. Tomasello (2005). "Human-like social skills in dogs?" Trends in Cognitive Science 9(9): 339-444 Miklosi, A. and K. Soproni (2006). "A comparative understanding of the human pointing gesture." Animal Cognition9: 81-93. Pointing gestures as cues • Experiments do try to control for olfactory cues

25. Things to note about experiments • Small number of subjects with repeated trials • Criteria is statistically different than chance • Results are typically aggregated • Typically subjects are adult pet dogs recruited from local training clubs, friends, etc.

26. Hare 2002

27. 9 out of 11 dogs used cue vs. 2 out of 11 for chimps Hare, B., M. Brown, et al. (2002). "The domestication of social cognition in dogs." Science 298: 1634-1636. Hare 2002 • The difference between dogs & chimps was startling, and the question was why?

28. Hare’s Three Hypotheses (2002) • “Canids in general are unusually flexible in the types of social information they can exploit” • “Domestic dogs ... have learned their skills during their individual ontogenies” • “Selection pressure on dogs during process of domestication for specific skills of social cognition and communication with humans”

29. No wolf performed above chance using any cue. 7 dogs used GPT, 5 used GP, 4 used P to find food above chance. 3 dogs used all 3 cues, 3 dogs used 2, and 1 dog used just one. Point Control Gaze, point Gaze, point, touch Hare, B., M. Brown, et al. (2002). "The domestication of social cognition in dogs." Science 298: 1634-1636. Dogs performed differently than ‘socialized’ wolves • This suggested to Hare that it wasn’t an ability common to canids

30. Differences aren’t significant, but interesting that litter-reared did better than family raised. Hare, B., M. Brown, et al. (2002). "The domestication of social cognition in dogs." Science 298: 1634-1636. Litter raised pups did the same as family raised pups • This suggested to Hare that it wasn’t developmental

31. 9-12 week pups did as well as 17-24 week pups • This suggested to Hare that there wasn’t a learned component

32. Hare’s big conclusion • “These findings suggest that during the process of domestication, dogs have been selected for a set of social-cognitive abilities that enable them to communicate with humans in unique ways.”

33. Things to think about... • Are there flaws with the experimental design and analysis? • There is an assumption that socialized wolves are the same as socialized dogs. Is this valid? • There is an assumption that extensive contact with humans prior to 8-12 weeks is required for pups to preferentially attend to humans. Is this valid? • There is an assumption that social learning doesn’t occur prior to 8-12 weeks. Is this valid? • There is an assumption that you can describe a generic pet dog, and that one can generalize across breeds. Is this valid?

34. Soproni (2002)

35. Soproni, K., A. Miklosi, et al. (2002). "Dogs' (Canis familiaris) Responsiveness to Human Pointing Gestures." Journal of Comparative Psychology 116(1): 27. Soproni, 2002 tried to characterize performance

36. Standing in middle Standing near one bowl or another Soproni, K., A. Miklosi, et al. (2002). "Dogs' (Canis familiaris) Responsiveness to Human Pointing Gestures." Journal of Comparative Psychology 116(1): 27. Soproni, cont...

37. Soproni... • Results • Hand position more important than movement • static gesture vs. dynamic gesture • When gesture isn’t clear uses body position as a cue

38. Miklosi (2003)

39. Miklosi - 2003 • Statement: behavioral changes [ability to use human cues] have a genetic basis because of the “selection pressure for dogs that were able to adapt better to the human social setting.” • Question: what is the exact nature of the behavioral changes that have occurred as dogs evolved from wolves? • Motivated by belief that the original Hare experiment did not control for “differential level of socialization” • Hare: semi-socialized adult wolves from Wolf Hollow • Miklosi: hand-raised wolves (n=4) living in a farm setting. Testing started at 4 months and continued for 3 months, every week.

40. Note: axis is incorrectly labeled Miklosi, A., E. Kubinyi, et al. (2003). "A Simple Reason for a Big Difference: Wolves Do Not Look Back at Humans, but Dogs Do." Current Biology 13(9): 763. wolves with ‘comparable socialization’ learned to use cue • One wolf was 80% accurate using distal pointing

41. Median latency before looking at person Median duration of glances at person Note wide variance (i.e., some dogs did persist at task & others gave up right away) Miklosi, A., E. Kubinyi, et al. (2003). "A Simple Reason for a Big Difference: Wolves Do Not Look Back at Humans, but Dogs Do." Current Biology 13(9): 763. Dogs looked back at person sooner & longer • This suggested to Miklosi that dogs were genetically biased to attend to people

42. Miklosi’s interpretation • Wolves aren’t as good at using human cues as dogs because of “their decreased willingness to look at the human” • Conversely, “preferential looking at the human seems to be a genetic predisposition of dogs”... • at this is the “foundation on which developmentally canalized complex communicative interactions can emerge between man and dog” • In other words, a genetic bias to look at people was a precursor to the co-evolution of dog-human communicative skills. Miklosi, A., E. Kubinyi, et al. (2003). "A Simple Reason for a Big Difference: Wolves Do Not Look Back at Humans, but Dogs Do." Current Biology 13(9): 763.

43. Things to think about? • The idea is appealing, but in this experiment are we just seeing a variance with respect to persistence and frustration? • lots of terriers don’t look back either... • wide variance in their own sample

44. Hare 2005

45. Hare 2005 • Hare’s statement: “dogs have an unusual ability for reading human communicative gestures... seems to have evolved during domestication” • Hare’s question: “unclear whether this evolution occurred as a result of direct selection for this ability... or as a correlated by-product of selection against fear and aggression toward humans” • Decided to test hypothesis using domesticated foxes that were explicitly bred to have reduced fear and aggression toward humans Hare, B., I. Plyusnina, et al. (2005). "Social Cognitive Evolution in Captive Foxes Is a Correlated By-Product of Experimental Domestication." Current Biology 15: 226-230.

46. Pups & fox kits between 8-16 weeks Hare, B., I. Plyusnina, et al. (2005). "Social Cognitive Evolution in Captive Foxes Is a Correlated By-Product of Experimental Domestication." Current Biology 15: 226-230. Pups & domesticated fox kits performed similarly • This suggested to Hare that this skill was a by product of selection for tameness

47. Hare, B., I. Plyusnina, et al. (2005). "Social Cognitive Evolution in Captive Foxes Is a Correlated By-Product of Experimental Domestication." Current Biology 15: 226-230. Temperament of farm foxes may interfere with performance • This experiment was consistent with Hare’s view that this skill was a side-effect of breeding for temperament

48. Hare’s conclusions... • 2 alternative explanations for dog’s ability to read human signals • Communication hypothesis: this ability was directly selected for during domestication • Correlated by product hypothesis: this ability is simply a by-product of selection for tameness • He believes his results support correlated by-product hypothesis... • Nothing was being selected for other than tameness (e.g., ability to read human cues) and yet foxes did as well as pet dog pups

49. Is this the whole story? • Hare’s argument: lowered emotional reactivity was selected for, and at a minimum, this set the stage. • How much more is needed? • Miklosi’s argument: that is not the whole story, social skills were selected for as well...

50. Things to think about... • At one level, all Hare is saying is that cognition takes place in an emotional context. This highlights the central role that emotions and temperament play in a dog’s choice of what to attend to, and what to do. • This is why we have devoted so much time to emotion and temperament • What are the specific mechanisms that make a pet dog emotionally prepared to interact & attend to humans? • This is why we devoted so much time to development