Wednesday, 20 August 2014

Summer Break / Summer Reading

Golden retriever puppies play on the beach
Photo: otsphoto / Shutterstick


Companion Animal Psychology Blog is taking a summer break. Meanwhile, on twitter and facebook we continue to share links to the best writing about companion animals and their people. Why not join us?

If you’re looking for some summer reading (and listening and viewing), these are some of our favourites:

We’re delighted that some CAPB stories now appear in Pacific Standard, including Dog Training, Animal Welfare and the Human-Canine Relationship 
 

Wild behaviour: The science of cats in boxes is explored in this Human Animal Science podcast with Sandra McCune.

We can’t resist this video from Japan of a cat falling asleep on a watermelon
 




Suddenly It’s Different is a beautiful post by Helen Verte of Love Wags a Tail.

A Contract with Your Dog by Maureen Backman at Mutt AboutTown 
 

In Husbandry for Paws: The Finale Heidi Steinbeck of Great Shakes Dog Training demonstrates how to trim a dog’s nails.  
 


Finally, every week Malcolm Campbell publishes a list of the best science writing on the web in Morsels for the Mind. There are always plenty of great animal stories. On his own blog, we especially enjoyed Seeing eye to eye – humans, dogs and squid stare across an evolutionary divide 
 
Companion Animal Psychology Blog will be back on 3rd September.  

Wednesday, 13 August 2014

The Effects of Owner Experience and Housing on Argentine Dogos

An Argentine Dogo dog sits in the garden
Photo: Lakatos Sandor / Shutterstock
What are the effects of an owner’s prior dog experience and the dog’s housing on behaviour problems? A survey of people with Argentine Dogos investigates.

Some previous research has suggested people who are first-time dog owners are more likely to have a dog with behaviour problems, perhaps because they don’t have enough experience. Also, sometimes people say breed experience is helpful. The aim of this study was to investigate this by looking at only one breed of dog, the Argentine Dogo.  

This breed was chosen because it was affected by dangerous dog legislation in Italy and, as the researchers put it, “was publicly blamed for posing a risk to human society.” Hence, it is an interesting choice for investigating the relationship between dogs and their owners.

The survey, conducted by Silvana Diverio (Perugia University) and Gabriella Tami, was completed by 94 owners who between them had 181 Argentine Dogos. Participants were recruited via the Italian Dogo Argentine Club and at dog shows. Given the method of recruitment, it’s not surprising that 23% of participants were breeders. In fact the participants had 22% of all the registered Argentine Dogos in Italy, with an additional group of unregistered dogs.

Questions asked about the owner’s prior dog experience, prior experience with the breed, and whether the dog lived in the owner’s apartment or was housed in a kennel. Questions on behaviour problems included aggression (“baring teeth, growling, snapping and biting”) and fear (“dog showing low posture with low or tucked tail and ears back or down, eventually trembling and/or attempting to escape”).  The survey was part of a wider study into Argentine Dogos and their owners in Italy.

One interesting feature of this study is that 79% of the owners with prior breed experience had obtained their dogs in order to breed them. The breed-experienced owners were significantly less likely to keep their dog in the house and less likely to take it to dog training classes than owners who had no prior experience with Argentine Dogos. The ‘naïve’ owners typically got their dog for reasons of companionship.

The dogs belonging to owners without prior dog experience were more likely to be destructive, to be afraid of other dogs, and to mount people – but they were also more likely to be obedient. These owners were more likely to take their dogs to training classes, and this is probably why their dogs were more obedient. It’s possible the reported problems reflect the fact that the dogs were living with their family, and hence more likely to be in situations where these problems might be observed, or it could be that inexperienced owners are not as good at socializing their dogs.

The results for owners who were new to the breed were similar to those of people who were new to dogs in general. Again, these owners were more likely to take their dogs to training classes and to say their dogs were obedient. And while they were more likely to report fear of children, their dogs were also reported as friendlier to strangers and unknown dogs, compared to the dogs belonging to breed-experienced people.

The dogs of breed-experienced owners were more likely to live in kennels. The authors say, “Aggressive and protective behaviors may simply result from the reduced opportunities that these confined dogs have to interact with people. Dogs who lived in kennels were also likely to be associated with breeding and with being owned by an expert owner. Expert owners reported lower participation in obedience training classes.”

The types of behaviour problems also changed with age, with younger dogs more likely to be reported as destructive and older dogs more likely to be reported aggressive to other dogs. 

The study is correlational and does not show causality. In addition, the inter-relationship of variables makes it tricky to pinpoint the effects of experience with dogs. Perhaps rather than showing the effects of experience, the results reflect the fact that attendance at dog training classes, and living in proximity with the family (rather than in a kennel), are positive for dogs’ behaviour and welfare. 

This is an interesting study and shows that more research is needed into the effects of owners’ general dog experience and breed experience. 

What breed was your first dog, and why did you choose it?

Reference
Diverio, S., & Tami, G. (2014). Effect of owner experience, living environment, and dog characteristics on owner reports of behavior of Argentine Dogos in Italy Journal of Veterinary Behavior, 9 (4), 151-157

Wednesday, 6 August 2014

Is it Important to Attend Puppy Class?

Is a one-off puppy party a suitable alternative to a six-week puppy class? Research says you can’t skip the socialization if you want a well-rounded adult dog.

A malamute puppy climbs on a wall while another pup watches
Photo: Zuzule / Shutterstock

A study by Ai Kutsumi et al (2013) of the Azabu University Graduate School of Veterinary Science compares four groups of dogs: those who attended a six-week puppy class, those who went to a one-hour puppy party, those who attended a six-week adult dog training class, and those who didn’t attend any puppy or training class at all. 

142 dogs took part and the groups were about equivalent in terms of age, gender, and breed mix. The dogs were aged between 6 months and 3 years at the time of testing. The study included a questionnaire and a 30-minute behaviour test at the dog’s home.

Dogs who attended the 6-week puppy class or the adult dog training class scored significantly better on response to commands, showing that dogs can learn obedience commands at any age. Dogs who had been to puppy class were significantly more likely to give a positive response to a stranger than those who had been to just a one-hour puppy party or not attended any classes at all. They also tended to do better than those who had only been to adult dog training. This shows that the socialization aspect of puppy class is important for the dog’s future behaviour.

The scientists say, “the behaviour test showed that participation in puppy class contributes to improving the positive response of the dog to strangers. This indicates that if an ordinary companion puppy participates in a puppy class for socialization at about 4 months of age, the dog is likely to remain friendly to non-family members at an acceptable level.” 

The one-hour puppy party arose because puppy class is not that popular in Japan, according to the scientists. However these results show that it is not a substitute for the socialization that occurs during a 6-week puppy class.

The puppy class, adult class and puppy party all took place at the SIRIUS Dog Training School Japan. The puppy class curriculum included basic training commands as well as bite inhibition, house training, and socialization with the other puppies and their owners. The puppy party was equivalent to just the first session of puppy class. The adult dog training class covered basic obedience for dogs aged from 5 months to 2 years. All of the classes were force-free and used positive reinforcement, and class sizes were small (4-8 puppies and 2-5 adult dogs). 

The results also showed links between behaviour tests and scores on the Japanese version of C-BARQ, a questionnaire designed to assess behaviour traits. If dogs had a C-BARQ score that suggests fear of strangers, they gave a less positive response to a stranger in the behavioural test. Also, there was a correlation between Trainability scores on the C-BARQ and the results on the behavioural test for response to commands. The researchers say this means that C-BARQ scores can be useful in detecting signs of problems that require intervention.

In addition, ongoing socialization with people and dogs, and more frequent training sessions, were all positive for the dog’s behaviour.

The results of this study show that attending puppy class is important for socialization with other puppies and people. Although a 1-hour puppy party might sound like an attractive option, it does not have the same beneficial results for the dog’s future friendliness.

If you've ever taken a pup to puppy class, or you're a dog trainer, what do you like best about puppy class?

Reference
KUTSUMI, A., NAGASAWA, M., OHTA, M., & OHTANI, N. (2013). Importance of Puppy Training for Future Behavior of the Dog Journal of Veterinary Medical Science, 75 (2), 141-149 DOI: 10.1292/jvms.12-0008

Wednesday, 30 July 2014

The Attentive Look of a Dog in Training

Researchers investigate the body language of a dog that is performing well in training.

A mixed-breed dog with brown eyes sits and looks up at the camera
Photo: Markus Balint / Shutterstock
A new study puts dogs through the first stage of a basic training task and analyzes eye contact and posture in the most successful dogs. The research by Masashi Hasegawa et al (Azabu University School of Veterinary Medicine) is motivated by a desire to improve people’s training abilities by helping them recognize the posture associated with successful learning. 

One of the neat things about this paper is that the study was done with completely untrained dogs. For obvious reasons, many canine science studies use well-behaved pet dogs of the kind that is calm when taken to a strange location like a university laboratory. While these studies are valuable, not all dogs are well-socialized and it’s important that research considers all kinds of dogs. What better dog for a study of dogs-in-training than one that is totally untrained?!

The dogs live at a place called the World Ranch in Osaka, Japan. 46 dogs took part, aged 1 to 6.5 (average 3 years), and a wide mix of breeds. 

Training was carried out by someone previously unknown to the dogs, in sessions of 5 minutes each that took place in the dogs’ exercise yard. The handler used food to lure the dog into a sit position. He only did this when he had the dog’s attention, but he did it as many times as he could in the 5 minute session. After this, there was a 3 minute rest, followed by a test in which the hand signal was performed on its own (without food) 20 times. Every time the dog sat on request, whether in the training session or the test, it was given a piece of food.

Each dog had three sessions like this a day, for three days, to make a total of nine sessions. The sessions were videoed so that the dogs’ body language could be analyzed.

The results showed a positive correlation between the number of trials in the training session and the number of correct responses in the tests. In other words, practice makes perfect: the more practice a dog had, the better it performed on the test. In addition, the age of the dog was not linked to the number of correct responses; dogs could learn at any age.

The dogs were divided into two groups for further analysis: those that had performed especially well on the tests, and the rest. This meant the body language of dogs that are successfully learning could be compared to those that are performing less well.

The high-achieving dogs had their eyes wide open, their mouths closed, their ears forward, and their tails were high but not wagging. Surprisingly, the researchers consider this in terms of dominance, the open eyes being seen as dominant but the other aspects of the posture not. It does not make sense to consider the relationship between dog and trainer as one of dominance; the dog is trying to understand how to earn the treat, and if it hasn’t figured it out yet then it shows a need for the trainer to make it clear.

The most interesting finding is that the wide eyes occurred mostly when the dog looked up at the handler’s face, showing that gaze from the dog to the handler is important in training. This is in line with Braem and Mills (2010), who also found a positive association between dogs looking at the handler and their performance in learning. Deldalle and Gaunet (2014) found that dogs trained using positive reinforcement gaze more at their owners during the sit command and when walking on leash than dogs trained using negative reinforcement, demonstrating a better relationship between dog and owner in the R+ group.  

This study only looked at the stage of using a lure. Dogs did not progress beyond this, even though they responded to the lure many times. One Papillion had 194 trials! (That must have been a happy dog). Even starting with a completely untrained dog, it is possible to teach ‘sit’ quickly. It would be nice to see the research repeated using an incremental training plan that progresses via hand signal to a verbal command. It's also possible body language will change in response to continued training, and future research could follow dogs as they learn a set of commands.

In fact the initial lure, although exactly where you would start, is too difficult for some dogs. When this is the case, it would be more appropriate just to expect their head to follow the lure, without going into a full sit at the beginning.  

We should be able to say that any dog training book will explain how to teach your dog the basics, but sadly this is not the case. Some books still recommend the use of unnecessary aversive techniques; if a book suggests hitting your dog, jerking the leash, or doing a so-called ‘alpha’ roll, discard it and choose another book instead! 

For an excellent example of how to fade the food lure when teaching sit, see this post on fading food lures and adding a verbal cue by Lori Nanan at Your Pit Bull and You. If you’re a keen trainer and want to get into the techie details, you’ll like Train Your Dog Like a Pro by Jean Donaldson. 

What’s your favourite dog training book and why?

Reference
Braem, M., & Mills, D. (2010). Factors affecting response of dogs to obedience instruction: A field and experimental study Applied Animal Behaviour Science, 125 (1-2), 47-55 DOI: 10.1016/j.applanim.2010.03.004 Deldalle, S., & Gaunet, F. (2014). Effects of 2 training methods on stress-related behaviors of the dog (Canis familiaris) and on the dog–owner relationship Journal of Veterinary Behavior: Clinical Applications and Research, 9 (2), 58-65 DOI: 10.1016/j.jveb.2013.11.004
Hasegawa, M., Ohtani, N., & Ohta, M. (2014). Dogs’ Body Language Relevant to Learning Achievement Animals, 4 (1), 45-58 DOI: 10.3390/ani4010045

You might also like: Do Dogs Get that Eureka! Feeling?  

Wednesday, 23 July 2014

The Adolescent Dog: One Last Chance?

A synthesis of the latest research on social influences on development suggests adolescence is an important time for mammals – including dogs.

A JRT counter-surfing in the kitchen
Photo: dezi / Shutterstock

Most people are familiar with the idea of a sensitive period for puppies that ends around 12 or 14 weeks. Is it possible that adolescence is also an important period for brain development and future behaviour?

Social experience plays an important role in shaping animal behaviour throughout development according to Sachser et al (2013). They consider the way the environment influences the mother and, in turn, the behaviour of her offspring (e.g. through stress hormones). This ensures the offspring is prepared for that environment as adults. 

While the paper looks at the prenatal period right through to adolescence, it is the section on adolescent animals that is of most interest. They write that “the adolescent phase may provide a last chance for correction if the future environment deviates from that predicted in earlier phases.”

Most developmental research has focussed on pregnancy and the period shortly after birth. During this time, maternal hormones and behaviour have a large impact on the development of offspring. However, some parts of the brain are still plastic (i.e. able to change and develop) into adulthood. This includes the hippocampus and amygdala.   

The scientists say, “There is increasing evidence that adolescence, that is, the gradual transition from childhood to adulthood, also represents an additional sensitive period (beyond the prenatal and early postnatal periods) in which behavioural profiles are routinely and profoundly shaped by social events.”

The potential for change during adolescence is necessary, they argue, because sometimes there will be a mismatch between the conditions in which the offspring is born and experiences very early life, and the environment in which it matures. In particular, they suggest future studies should examine the effects of this kind of mismatch, in order to find out more about this stage of development.

One example of the influence of the social environment in adolescence can be found in guinea pigs. If they spend their adolescence in colonies that include both males and females, they develop good social skills. As adults, they are able to get on with other guinea pigs in the colony without being aggressive; they are also able to become part of a new colony with unfamiliar guinea pigs. However, if they spend adolescence as part of a male-female pair, they become aggressive to unfamiliar males. Thus, the adolescent experiences have shaped adult behaviour. 

The research considered by Sachser et al is mainly about mice, guinea pigs and wild cavies, but these ideas are thought to apply to the mammalian brain in general. They tie in with work on plasticity in the human brain. For example, Dr. Bruce Perry (2006) says that “important neurodevelopmental processes continue to take place throughout childhood and adolescence as the brain’s systems become more complex. Major cortical restructuring and myelination continue into early adult life.”

Writing about the implications for dogs, Riemer et al (2014) say,  “… a major reorganisation of the central nervous system occurs during puberty, and there is growing evidence that adolescence can be considered as an additional sensitive period (beyond the prenatal and early postnatal periods), with profound effects on future behaviour (reviewed in Sachser et al 2013). There is evidence that steroid-dependent adolescent brain and behavioural development can be modified by social experience. Thus, experiences after the first sensitive period of socialisation, and in particular during adolescence, will also play an important role in determining the adult animal's behaviour.” 

This is good news for poorly socialized adolescent dogs, as it means there is still an important window of opportunity in which to improve their behaviour. This is an age at which many dogs are surrendered to rescue organizations because they are no longer cute puppies and their increased size means their behaviour has become problematic. A better understanding of development during this stage would therefore benefit many dogs.

So does this research mean we don’t need to worry about puppy socialization anymore? Absolutely not! This is the most important time for ensuring your puppy will grow up to be a calm, friendly adult dog. (For suggestions, see this excellent article by Anne Springer on ‘five things you can do to bite proof your puppy’).

However, if you have an adolescent dog that hasn’t been socialized, it means it would be a good idea to build positive socialization experiences into their training plan.

Not enough is known about canine development, and more research is needed to confirm the biological and behavioural changes that take place during adolescence. We look forward to learning more about this important stage of development. The papers by Sachser et al (2013) and Riemer et al (2014) are open access and can be read at the links below.

What was your dog like as an adolescent?

References
Perry, Bruce D. and Szalavitz, Maia (2006) The boy who was raised as a dog and other stories from a child psychiatrist’s notebook. NY: Basic Books.
Riemer, S., Müller, C., Virányi, Z., Huber, L., & Range, F. (2014). The Predictive Value of Early Behavioural Assessments in Pet Dogs – A Longitudinal Study from Neonates to Adults PLoS ONE, 9 (7) DOI: 10.1371/journal.pone.0101237  
Sachser, N., Kaiser, S., & Hennessy, M. (2013). Behavioural profiles are shaped by social experience: when, how and why Philosophical Transactions of the Royal Society B: Biological Sciences, 368 (1618), 20120344-20120344 DOI: 10.1098/rstb.2012.0344

Wednesday, 16 July 2014

Do Puppy Tests Predict Adult Dog Behaviour?

A new study follows dogs from neonates to adults to find out if puppy tests predict adult behaviour.

Golden retriever puppy nose to nose with its mother
Photo: Mikkel Bigandt / Shutterstock

Lots of people want to know if a puppy’s behaviour will tell you what it will be like as an adult dog. From people choosing a pet dog from a breeder’s litter, to organizations training service, police or military dogs, making the right choice of puppy could really help later on. But there have long been concerns that puppy personality tests don’t necessarily predict adult behaviour. So Stefanie Riemer et al of the Clever Dog Lab tested border collies as brand new puppies, older puppies, and adult dogs, to investigate.

Most previous studies have looked at dogs bred to be working dogs. This study is especially interesting for pet owners because it looked at pet dogs. 

99 neonate Border Collie puppies were tested between 2 and 10 days old. 93 of them, and a further 41 dogs, were tested at 40 – 50 days old. Finally, once all the dogs had found homes, 50 of them were tested again when they were between 1.5 and 2 years old.

The first two testing sessions took place at the breeders' homes, and the final session was conducted at the lab with the owner present. 

The neonate tests included how hard the puppy would suck on the experimenter’s finger, how active the puppy was and how much noise it made when it was isolated from the mother. The puppy tests had 11 subscales that included a greeting test, a brief simulated veterinary exam, and how much the puppy would explore in a new room. The adult tests were part of a wider study, and included greeting and exploration tests, as well as response to a threatening approach.

The results showed very little correlation between tests at the different ages. In fact, the only significant correlation was on the exploration test for puppies and adults. 

The scientists say, “there was a lack of correspondence between the behaviour of neonates and the same dogs during the puppy and adult test, implying a lack of validity of this tool for making predictions regarding future behaviour. The results furthermore indicate low predictive validity of the puppy test conducted at 6–7 weeks of age, as activity during room exploration was the only behaviour that was significantly related between the puppy test and the adult test.”

A useful note for future research is that the strength of sucking in neonates was related to weight, and so this needs to be taken into account if this test is used. One problem the scientists note is that the tests were structured to the age of the puppy, and so were not the same at each age. Identical tests would be more likely to correlate.

The finding that puppy behaviour does not predict the behaviour of an adult dog will disappoint many. But the flipside is there is much that owners can do to influence the behaviour of their dog, which surely is a good thing.

The scientists say this is not really surprising, given how much puppies change in the time from newborns to becoming an adult dog. Many people are aware of the idea of a sensitive period when it is important to socialize puppies, and it should be noted that the puppy tests took place during this period. 

In addition, Riemer et al say, “environmental differences can be expected to have a greater effect on behavioural variability in our sample of pet dogs compared to the working dogs of previous studies, which tend to be kept under more uniform conditions and follow standardised training regimes. Given that dogs are highly responsive to their social environment, the role of the owner should not be forgotten.”

The pups in this study came from breeders and spent their early days with their mum. The results might be different for puppies from other sources. For example, Franklin D. McMillan et al (2013) found that behavioural problems were more likely in adult dogs if they had been obtained from a pet store instead of a breeder. Similarly, Carri Westgarth et al (2012) found that if neither parent was seen when obtaining a pup, it was 3.8 times more likely to be referred for behavioural problems. So the source of a puppy is important for adult behaviour, even if personality tests aren’t. 

This study makes a valuable contribution to the literature on behaviour and personality tests in puppies and dogs, and also shows the need for more research on development in puppies.

What do you look for when choosing a puppy?

Reference
McMillan, F., Serpell, J., Duffy, D., Masaoud, E., & Dohoo, I (2013). Differences in behavioral characteristics between dogs obtained as puppies from pet stores and those obtained from noncommercial breeders Journal of the American Veterinary Medical Association, 242 (10), 1359-1363  
Riemer, S., Müller, C., Virányi, Z., Huber, L., & Range, F. (2014). The Predictive Value of Early Behavioural Assessments in Pet Dogs – A Longitudinal Study from Neonates to Adults PLoS ONE, 9 (7) DOI: 10.1371/journal.pone.0101237  
Westgarth, C., Reevell K., & Barclay R. (2012). Association between prospective owner viewing of the parents of a puppy and later referral for behavioural problems The Veterinary Record , 170 (20)

You might also like: Do Dogs Have Stable Personality Traits?

Wednesday, 9 July 2014

Sub-Optimal Choice in Dogs: Cheese or Cheese and Carrot?

Evidence suggests dogs do not always make the best choice. A new study finds that far as food choice is concerned, they use the same heuristic previously demonstrated in humans and monkeys.

A white dog nibbles on a carrot that it holds between the paws
Photo: Igor Sokolov (breeze) / Shutterstock
Earlier research has found that if people are asked to estimate the value of a set of 24 good condition dishes vs a set of 40 dishes (of which 31 are in good condition), they tend to think the former is more valuable. The broken dishes seem to detract from the fact the second set has more dishes in good condition. This is known as the ‘less is more’ effect.

This effect has been demonstrated in monkeys, too. Monkeys like grapes and they also like slices of cucumber, although not as much. If given a choice between a grape vs a grape and a slice of cucumber, they tend to choose the grape.

Does the same hold true for dogs? Kristina Pattison and Thomas Zentall (University of Kentucky) set out to investigate.

The experiment took place in a plain room at the University. Since some dogs can be nervous in a new environment, dogs were given 5 minutes to investigate the room, and then offered a piece of cheese, a piece of carrot, followed by a piece of cheese with a piece of carrot. Dogs had to eat all of these items in order to qualify to participate. 

In the experiment, dogs were given a choice between a slice of cheese or a slice of cheese and a slice of carrot. After demonstrating that she had both items, the experimenter held her hands out with the items in the palm, and the handler released the dog. As soon as the dog touched one of her hands, the experimenter closed the other hand so the dog only had access to the hand it had chosen. The dog was allowed to eat the item(s), then went back to the handler to repeat the experience.

Ten pet dogs took part, including five mixed breeds, a Cavalier King Charles Spaniel, a Siberian Husky, a Belgian Tervuren and a Golden Retriever (the researchers don’t say what the other dog was). 

The dogs showed a significant preference for a single piece of cheese rather than a piece of cheese and a piece of carrot. On average across all the dogs, cheese plus carrot was chosen only 27% of the time. 

One of the ten dogs actually showed a consistent preference for cheese plus carrot. Interestingly, this was a dog that was adopted as an adult rescue, having previously been a stray. The authors hypothesized that he may have had a greater motivation for choosing two items of food over one.  In fact, they point out that the dogs in this study and the monkeys in the monkey study all had relatively little motivation, since they are well-fed and not starving.

Some dogs have a preference for going to the left or right hand, and these dogs were weeded out in pre-tests. In addition, since it was theoretically possible that dogs have a preference for a single item rather than two items, there was another test in which dogs were given a choice between one slice of cheese and two slices of cheese. They picked two slices of cheese 95% of the time.

Why would people and dogs make this kind of choice? The authors say, “The less is more effect, first demonstrated in humans, is an affect heuristic that results in a preference for the qualitative over the quantitative evaluation of options. Its function appears to have been the rapid evaluation of alternatives. It is likely that in many cases it is relatively easy to judge the qualitative value of alternatives but perhaps more difficult to judge their quantitative value, and when rapid decisions are necessary, such heuristics may be quite functional. For example, within-species competition may favour rapid decisions because hesitation may result in losing food to a faster competitor.”

Given the small sample size, further research is needed to see if this fascinating result applies widely.

The nice thing about this experiment is that it is relatively easy to replicate at home. Why not give your dog this choice a few times, and report back?

Reference
Pattison, K., & Zentall, T. (2014). Suboptimal choice by dogs: when less is better than more Animal Cognition, 17 (4), 1019-1022 DOI: 10.1007/s10071-014-0735-2