Do Tamed Domesticated Dogs (Canis familiaris) Ignore Deceptive Human Cues When the Actual Food Location is Visible?

Transcription

1 The Huron University College Journal of Learning and Motivation Volume 51 Issue 1 Article Do Tamed Domesticated Dogs (Canis familiaris) Ignore Deceptive Human Cues When the Actual Food Location is Visible? Candice Dwyer Follow this and additional works at: Part of the Psychology Commons Recommended Citation Dwyer, Candice (2013) "Do Tamed Domesticated Dogs (Canis familiaris) Ignore Deceptive Human Cues When the Actual Food Location is Visible?," The Huron University College Journal of Learning and Motivation: Vol. 51: Iss. 1, Article 6. Available at: This Article is brought to you for free and open access by the Psychology at Scholarship@Western. It has been accepted for inclusion in The Huron University College Journal of Learning and Motivation by an authorized administrator of Scholarship@Western. For more information, please contact kmarsha1@uwo.ca.

2 Do tamed domesticated dogs (Cams familiaris) ignore deceptive human cues when the aetual food location is visible? Candice Dwyer Huron University College Eight dogs were selected as the subjects in a study to determine if dogs could detect deceptive human cues and consequently ignore them. More speeifically, if dogs would ignore when a human dishonestly cued them towards a bucket with no food in favour of a bucket that contained food. Dogs have been shown to actually listen to deceptive human cues when food was hidden from them rather than ignore deceptive cues (Petter, Musolino, Roberts, & Cole, 2009). However, this study utilized transparent food containers to ensure the dog was able to visually detect where the food was correctly located. Hence, this study hypothesizes that even when the dog gets dishonestly cued to an empty bucket, the dog will now be more likely to ignore deceptive human cues in favour of a bucket that obviously contains food. This is presumably because in this situation, unlike studies that preceded it, the dog can blatantly see the food is not in the same loeation that the human cue directed them. Although, in contrast to the hypothesis, it was shown that dogs did not show a preference for the transparent bucket that contained food over the empty bucket the experimenter cued them to. While dogs approached the truthful human cue almost 100% of the time, dogs were shown to approach the deceptive human cue in approximately equal proportions to a non-cued transparent bucket that contained a visible food reward. Thus, dogs do not significantly more than chance ignore deceptive human cues, and therefore cannot necessarily detect human deception. Certain animal species have developed an ability to become sensitized to attend to humans' social communicative behaviours and respond accordingly (Petter, Musolino, Roberts, & Cole, 2010). Wild animals, like the chimpanzee, have not shown the same responsiveness to humans' communicative gestures (Brauer, Kaminski, Riedel, & Tomasello, 2006). However, under controlled conditions, for example, chimpanzees that have been bred in captivity and thus, while innately wild, have been tamed, can demonstrate the ability to respond to human communications (Hare & Tomasello, 2005). Species that have evolutionarily naturally selected a tolerance for and subsequent

3 companionship with humans in order to reap reward, animals that are considered domesticated, do not necessarily show a sensitization to human communicative behaviours (Udell et al., 2010). Dogs have been domesticated for tens of thousands of years (Petter et al., 2010). Conversely, feral dogs, which are domesticated and untamed, do not show a docile responsiveness to humans (Coppinger & Coppinger, 2001). In contrast, tamed dogs have long been shown to understand and respond correctly to human cues (Hare & Tomasello, 2005). Thus, not only is it clear that domestication can predispose animals to show sensitivity towards humans, it is not necessary. Rather, the overall mitigating factor that causes animals to show responsiveness to humans' gestures is actually tameness. It follows, that animals that are both domesticated and tamed, for example, household pet dogs, would probably be the strongest example of an animal that is highly sensitive and receptive to certain common communicative gestures from humans, for instance, points and gazes, which indicate locations of hidden food (Udell et al., 2010). The present study examines domesticated tamed dogs, household pets, in their ability to respond to human points. There is abundant empirical evidence that dogs can attend to and are receptive to human behaviours, more specifically, points, nods, gazes, and the like (Hare & Tomasello, 2005; Udell, Giglio, & Wynne, 2008; and Udell & Wynne, 2011). Petter et al., (2009) examined whether tamed dogs could not only accurately respond to directive human cues in this manner but also to deceptive human cues. In other words, could domesticated dogs detect dishonesty and thus ignore these cues? In this design, one experimenter correctly cued the dog with vocalizing the dog's name followed by "look" with their arm extended and index finger pointed down to a brown, opaque bucket with

4 food hidden inside it, hereafter ealled the eooperator. Conversely, another experimenter dishonestly cued the dog to the bueket that did not contain food in the same manner as the eooperator cued the dog, hereafter called the deceiver. The study postulated that since tamed domesticated dogs have been proven to be highly sensitive to human cues these domesticated species might also be sensitive to a misleading human cue. Furthermore, the study revealed that dogs were more reluctant to approach either bucket when the human cue was dishonest compared to when the cue was truthful, which means that dogs are in fact somewhat receptive to deceptive cues. However, overall the dogs approached the bucket cued by the deceiver and the alternate bucket that contained food in roughly equal proportions. Thus, domesticated dogs apparently had an innate or learned tendency to be obedient and listen to human cue. Consequently, dogs approached the location humans cued them more often and it was determined that dogs did not tend to ignore the deceptive points in favour of locations with a food reward. The present study is an extension of the Petter et al., (2010) study that dogs cannot detect when human cues are deceptive and thus should be ignored in favour of locations that actually contain food rewards. The purpose of this design is to determine whether dogs can effectively ignore deceptive human cues when the correct location of food is more obviously detectable to the dog. The Petter et al., (2010) study used opaque, brown buckets that visually and olfactorily hid a food reward while the present study used transparent open eontainer to make the reward visually detectable to the dog. Thus, the present study hypothesizes that when dogs presumably visually perceives the correct location of food it will enable them to decide to ignore dishonest human points in favour of a bucket with food in it.

5 Method Subjects The subjects for this study were eight dogs {Canis familiaris), of six different breeds. There was a Saint Bernard, two Boston terriers, two English bulldogs, a Vizla, a Labrador retriever, and a Great Dane. The Labrador retriever, one of the Boston terriers, one English bulldogs, and the Great Dane were female and the remainder were male. The Saint Bernard and male Boston terrier were rescue dogs that had been with the current family for at least a year. Five of the dogs were 4 years old or younger while three of the dogs were over 6 years old. Six of the dogs were over 50 lbs and the other two were less than 30 lbs. All of the dogs were domestieated house pets. None of the dogs had prior experience in behavioural experimentation. Apparatus The study was conducted at each of the dogs' homes in the Toronto, Ontario. All the dogs were tested in their primary residence in a quiet location, such as a hallway or foyer. This ensured other people in the home or novel stimuli from the outside environment did not serve as a distraction. The dogs were not tested in the same room their food was stored or consumed, to prevent distraction from the smell. Two rectangular transparent containers were used. The inside of the two containers was 31.8 cm long by 19.8 cm wide with a width of 10 cm and were manufactured by Iris USA Inc. The reward used in the experiment was hot dog manufactured by Maple Lodge Farms Zabiha Halal Chicken Wieners. The hot dogs were each 13 cm long and 2 cm thick. Dogs that weighed 50 lbs or more received a quarter of the hot dog, 3.25 cm long, each trial and an eighth, 1.63 cm, was used for dogs under 50 lbs. Finally, a small piece of masking tape was used to mark the floor 2 ft from the buckets, 8 ft from the dogs.

6 Procedure Each dog had one female and one male tester. For half of the dogs the female was the eooperator while the male was the deceiver, while the other half the male was the eooperator and the female was the deceiver. These roles were initially chosen at random then were kept consistent for each dog for the duration of both test sessions. Five of the dogs were tested while on their leash, held by the experimenter who did not cue the dog during the trial, while the owner controlled the other dogs. Forty trials were conducted over two sessions, twenty trials each session. The two sessions were conducted 24 hours apart. For the first session alternating bloeks of five trials were conducted with the eooperator and deceiver in order for the dog to learn the outcome of approaching each bucket. For the second session, the order of the eooperator and deceiver were in a randomized order that guaranteed ten trials with each experimenter were conducted. Prior to the start of testing the dog was familiarized with the transparent containers and the reward. In that, the dogs were allowed to eat a couple quarters of hot dog out of each of the two containers on the floor. All the dogs willingly ate from each container. The buckets were then placed on the floor 5 ft apart and the dog was moved so it was 10 ft. from the buckets. The dog was subsequently turned to face away from the containers so when the bucket was baited it was not visible to the dog. For each trial the container on the left or right was chosen at random and was baited with the hot dog while the remaining empty container was rubbed with hot dog to ensure the bueket gave off a hot dog odour. For the eooperator trials the designated experimenter stood behind the container with hot dog in it. For the deceiver trials the experimenter stood behind the empty bucket.

7 Once behind the bueket the experimenter indicated to the owner the trial could begin by saying, "OK" and the dog was turned to face the buckets. The experimenter then cued the dog to the container he or she was behind by extending his or her right arm downwards with their index finger extended and verbally enticed the dog with his or her name followed by "look". The dog was then allowed the approach a bucket; either the experimenter who did not cue the dog dropped the leash or the owner let go of the dog. If the dog approached the container with food in it the dog was allowed to consume the food readily. If the dog approached the empty container it was given no reward. A choice was considered a choice when the dog was less than 2 ft away from the buckets. If the dog was less than 2 ft from the buckets the choice was final and the dog could not change their mind. However, if the dog was more than 2 ft from the buckets the dog was allowed to pause and then decide which bucket to choose. The dog was turned away again at the end of each trial while the experimenter re-baited a random container in preparation for the next trial. Results On eaeh trial the dogs responded in one of two ways: either the dog approached the bucket cued by the experimenter or approached the alternate bucket. On eooperator trials if the dog approached the bucket cued by the experimenter it was deemed a correct choice whereas if the dog chose the bucket not cued by the experimenter, the empty bucket, it was considered an incorrect, or wrong, choice. On deceiver trials it was vice versa: if the dog approached the empty bucket, the bucket cued by the experimenter it was considered a wrong choice whereas if the dog approached the alternate bucket it was a correct choice. The dog always made a decision almost immediately. The proportion of

8 choices the dogs' ehose the correct and wrong buckets plotted over both sessions is shown in Fig 1. The left panel records the tendeney of the dogs to approach each bucket during the eooperator trials whereas the right panel reveals the tendency of the dogs to approach each bucket during the deceiver trials. It can be gathered that proportion of correct choices on eooperator trials during session 1 and 2 was 0.89 and 0.94, respectively. In contrast, on deceiver trials, the proportion of choices to approach the correct bucket over sessions 1 and 2 was 0.44 and 0.60, respectively. A chi-square goodness of fit test was conducted for each of the two sessions. On the first day of testing there was a significant departure from chance that the dogs more frequently chose the correct bucket, the bucket that contained food, over the wrong bucket, the bucket that was empty, = (1) = 36.2, p <.05. Similarly, the second day of testing also resulted in a significant departure from chance that the dogs choose the eorrect bucket more frequently than the wrong bucket, = (1) = 25.6, p <.05. Additional chi-square goodness of fit tests were conducted that examined the eooperator and deceiver trails on eaeh day. On both the first and second day the dogs significantly chose the correct bucket, the bueket with food in it, more frequently than chance, X^ = (1) = 24.0, p <.05 and X^ = (1) = , p <.05, respectively. Although, on closer examination of the deceiver trials, the dogs did not choose the correct bucket over the wrong bucket more frequently than chance on the first day, X^ = (1) =.625, p <.05, nor on the second day of testing, X^ = (1) = 1.6, p <.05. In other words, while the dogs did choose the bucket with food at a significantly higher frequency than chance over the wrong bucket when a human truthfully cued them to the bucket with food, this was not the ease when the human dishonestly cued them to the empty bucket. The dogs ehose the

9 correct bucket roughly equally to the wrong bucket when the human cue was towards the empty bucket. Discussion While there was a significant departure from chance on each day of testing overall, which indicates that the dogs did choose the bucket with food in it more frequently than the empty bucket on each day of testing, when solely the deceiver trials were analyzed, there was no significant departure from chance. The dogs chose the bucket with food and the empty bucket roughly equally on deceiver trials in both sessions. Therefore, the results of the study by Petter et al., (2009) are upheld, that dogs eannot detect deceptive human cues. More specifically, that dogs can learn to approach an honest cue significantly more than chance but fail to learn to ignore dishonest cues significantly more than chance. Thus, the hypothesis that tamed dogs would be able to detect and ignore human deceptive cues when the food was obviously visible to the dogs rather than hidden from them was not supported. In the study by Petter et al., (2009) it was indicated that on the deceiver trials the dogs chose the bucket cued by the deceiver and the alternate bucket that contained food at approximately equal frequencies. Therefore, the dogs did not significantly show that they could ignore deceptive human cues and choose the bucket with food in it. However, the dogs did show a strong hesitation to choose a bucket at all on deceiver trials. While on the eooperator trials the dog always chose a bucket within 30 s, on deceiver trials the dogs refused to make a choice a significantly higher proportion of times and their choices had significantly longer latency periods. There was a clear hesitance to listen to the deceiver whereas on eooperator trials there was almost an immediate response to listen to

10 the tester. This reveals that the dog did in fact detect a difference between the eooperator and deceiver; however, the dogs' innate domestication or learned tameness caused them to listen to rather than ignore the deeeiver's cues (Petter et al., 2010). Dissimilarly, in the present study the dogs always made a choice, almost immediately, as to which bucket they would go to. It follows that, arguably, this is evidence that attests the dogs did in fact visually perceive the correct location of the food and thus were aware the human cue was dishonest. This provides further evidence that dogs have either an innate tendency or learned ability to obey humans. Even when they can perceive food in another location the dogs immediately choose to listen to human cues. This study provides additional evidence that dogs have a strong propensity to obey humans, sinee the dogs do not tend to ignore deceptive human eues, even when it is visually known to dogs that the cue is dishonest. Additional support for the present study's results come from a study conducted by Kundey, De Los Reyesm, Arbuthnot, Allen, & Coshun, (2010), who demonstrated that when food is visible to the dog, in transparent containers, dogs show a preference to the visible food over hidden food. This is paralleled in the present study's results in that both studies used transparent containers to ensure the dog could perceive the reward, rather than the dogs plaeing sole reliance on the human cue. Rather than dogs showing a preference for the correct bucket, a more logieal conclusion would be that the dogs had an overall preference for the food that was blatantly visible, which is supported by the present study that each session overall showed a significantly higher proportion of choices to approach the bucket with food. However, the results of the deceiver trials alone show there is a clear overriding desire and preference of dogs to obey a human cue

11 even when arguably aware that the cue is deceptive. In other words, overall, in the present study, there is a significant departure from chance that dogs choose the visually perceivable food reward over an empty bucket. The evidence shows a palpable preference for dogs to choose visual food over hidden food. Regardless, since the dog made a choice of which bucket to approach with virtually no latency between the human cue and the choice of which bucket to approach, even though the dog did in fact distinguish the proper location of food and knew the cue was dishonest, the tendency of domesticate tamed dogs to listen to human cues is stronger than their desire to approach food. This provides further support of the results of the study conducted by Petter et al., (2010). There are some limitations to the present study that should be discussed. Firstly, the quantity of trails and sessions was in retrospect not enough. In the study by Petter et al., (2009) over 200 trials were conducted over five sessions to determine whether dogs were receptive to dishonest human cues. However, due to time restrictions, only two sessions were conducted with 20 trials for each dog each day. While in the study by Petter et al., (2009) trials of the eooperator and deceiver were initially completed in alternating successive blocks and the final fifth session used a random order that ensured 20 of each eooperator and deceiver trials the present study only used one session of alternating eooperator and deceiver successive five trial blocks and then the second day was in a random order. The limited number of trials and sessions could have contributed to the dogs' decision to listen to the deceptive human cue. The dog may not have had the chance to learn which person was a liar and which person was telling them the truth. It would be beneficial to conduct the same study over a longer period of time with many

12 more sessions and trials. This could reaffirm that dogs couldn't detect human deception even when it is visually obvious it was a dishonest cue towards food. In contrast, the increase in trials and thus, chanee to learn who the dishonest experimenter was, could result in a higher proportion of correct choices to go to the bucket not cued by the experimenter compared to listening to the human demand. Another limitation to the study is that there was 10 ft between the buckets and the dog upon the initiation of each trial. Some of the dogs were considered giant dogs, over 150 lbs. For instance, one of the giant breeds of dog, the Saint Bernard, only ignored the deceptive human cue and chose the bucket with food for 20% of deceiver trials. The piece of reward in each bucket was very small relative to the size of the dog. It is possible that the reward was not eompletely visible to this particular subject and the dog may have not noticed the reward in the same manner the rest of the subjects did. Thus, thus subject may have simply ehosen the bucket that they were cued towards, even on deceiver trials. More simply, some dogs may simply not have seen the reward despite convincing evidence as to otherwise. As evident in the video records of the deceiver trials on the second day of testing it is clear some dogs walk up to the buekets, pause approximately 2 ft away, look at each bucket, then make a decision. It would be a legitimate improvement to conduct the study again with a smaller distance between the transparent bucket and the location the dog is in at the start of each trial to ensure the dog can see the reward. Another limitation is that the two experimenters were the owners of one of the dogs. This could have easily contributed to this particular dog not performing as well as the others. While on the second day of testing the majority of the dogs chose the correct bucket around 70% of the time on deceiver trials, the dog tested by the owners only chose

13 the correct bucket on deceiver trials 40% of the time. This dog could have had a stronger tendency to listen to the human cue than the other dogs. Hence, the study could result in a stronger departure from chance to piek the bucket with food as opposed to the one cued by the deceiver if the experimenters did not own and therefore did not regularly demand and eontrol one of the subjects. Finally, the latency period between when the dog was enticed and when the dog approached a bucket was not recorded in the present study. In the study by Petter et al., (2010) it was shown that the dogs significantly hesitated before making a decision as to which bucket to approach and refused to approach either bucket a significantly higher proportion of times compared to eooperator trials. Again, this demonstrates that the dog could detect a difference between the eooperator and deceiver. It would be beneficial to re-conduct the study in order to determine if in fact the dogs in the present study could detect that were was a difference between the eooperator and deceiver trials. Overall, there is a general consensus within the scientific community that tamed dogs, while responsive to human gestures and cues, are not responsive to similar cues that are instead misleading, whether the correct response visually obvious or not.

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