It is important to gain a Theory of Mind (ToM), an understanding of self and others thoughts, beliefs and feelings even if they are different to our own, for social maturity and knowledge of the world (Wimmer & Perner 1983). One way to measure ToM is through false-belief tasks, as designed by Wimmer and Perner (1983) originally with children, which has been adapted to adults (Apperly, Riggs, Simpson, Chiavarino & Samson, 2006) non-human primates (Call & Tomasello, 1999) and other mammals (Marino, et al 2007). Adaption of ToM tasks can help understand if this higher cognitive function (HCF) is distinctly human or not.
Santos (2006) investigated ToM in 27 Rhesus Macaque (Macaca mulatta), who were shown two translucent containers 15cmx14cmx10cm with hinged lids. Inside both of these containers were grapes, highly rewarding to Rhesus Macaque’s (Santos, 2006). Both of the translucent containers were covered in 20 small brass gilt jingle bells using thin metal wire, 8 on the side and 12 on top. One container had silent jingle bells and the other container was noisy, but they were visually identical.
Rhesus Macaque’s are motivated to take novel food especially when competitors are not watching such as humans. Therefore, in this study there were two human experimenters, one was a competitor and the other a cameraman. The cameraman selected a Rhesus Macaque that was away from the main group and proceeded to record them from 5 meters away. The competitor then went up to the subject and showed the grapes within the containers and the noise element, it was counterbalanced whether the noisy container was on the left or right.. At 2m away from the containers, the competitor then squatted down and placed his head between his knees, facing the ground. From this position, the competitor could not see the subject or the containers, but could easily look up from this position at any moment. The subject was then given one minute alone with containers and it was coded by the cameraman and a blind experimenter which container they touched first. There is only one trial in this experiment to avoid practise or reduction of perceived competition.
False-belief tasks have been disputed as a good measure of ToM due to confounders such as language and Executive Function abilities, Bloom and German (2000) however; an ecologically valid ToM auditory task is an adaptive advantage of the aforementioned study as it uses the aspects of the Rhesus Macaque lives in the wild, noises and competition, (Santos 2006).
ToM has been researched in bottlenose dolphins (Tursiops truncates) which are further from the lineage from humans, still with the same common ancestor, (Marino, et al 2007) (See figure 1).
Figure 1: Lineage of mammals as proposed by Foote (2015)
It is proposed that testing HCF in a mammal with a different common ancestor will help understand if ToM is distinctly related to one common ancestor from humans or another common ancestor between humans and Elephants, (Byrne, Bates & Moss, 2009). Elephants knowledge of time and tool use has been researched (Hart, Hart, McCoy & Sarath, 2001), although this is incomparable to Monkeys tool use (Hart, Hart, Pinter-Wollman 2008), and their causality (Nissani 2006) yet their knowledge of ToM has yet to be explored. The proposed research will adapt the aforementioned study by Santos (2006) to Elephants (Loxodonta Africana) as they have shown evidence of self-recognition (Plotnik, 2006). Plotnik (2006), tested three female Elephants, in a Bronx zoo to see if they had Self-Recognition through glow-in-the-dark paint on their forehead in a mirror, over half passed the test, Self-Recognition evidence in Elephants is the first step of ToM as this needs to be inhibited to understand different thoughts of others. Furthermore, there is qualitative evidence of ToM as Elephants care for ill family members, unique mammal behaviour other than humans (Plotnik 2010; Plotnik & de Waal 2014).
This study will have 6 Adult African Elephants (Loxodonta Africana) from Chester zoo (Rees, 2009), one male and five females – the breeding male Anug-Bo, female Maya, Thi Hi Way, her daughters Sithami Hi Way and Nandita Hi Way and Sithami’s daughter Sundara Hi Way, as used in previous studies (Rees, 2009).
In enclosure 1 there will be two translucent containers 32cm x 30 cm x 25 cm and a clasped lid validated with elephants by Nissani (2006) (See Figure 2). As African elephants in captivity are only fed by the keepers it is rare that they would be given treat food (Rees 2009), therefore using 5cm sugarcane, used by Nissani (2006), they will respond well. Both of the translucent containers will be covered in 40 small brass gilt jingle bells using thin metal wire, 16 on the sides and 24 on the top, one container will be silent and the other noisy, but visually identical. This task will work well as African Elephants respond better to auditory stimuli than visual, Bates (2008).
As in Santos (2006) study, this experiment will have two human experimenters, one as a competitor, a trained and familiar zookeeper, and a cameraman. As demonstrated in Povinelli (1989), Elephants are more likely to go for food that a dominant other (human) is unaware of, similar to the Rhesus Macaque in Santos (2008). Both the competitor and the cameraman will be in enclosure 1 with a set of containers, see figure 2, a safe distance away from the herd (Greco, Brown, Andrews, Swaisgood, & Caine 2013). The cameraman will select an elephant away from the herd in enclosure 2 (See figure 2).The dividing fence will have two holes big enough for the elephants trunk (20cm), as used by Nissani (2006). The competitor will then demonstrate the containers in enclosure 1, first showing the sugarcane in the boxes and the auditory component. It is known that Elephants can differentiate between noises (Heffner & Heffner, 1982). It will be counterbalanced whether the noisy container is on the left or right, and that one container makes a noise and the other does not. It is known that Elephants can dissociate between objects, (Hyatt, 2013).
Figure 2: Relative distances between subject, competitors and Apparatus
It will then be recorded by the cameraman and blind experimenter which container is touched first when the Elephant puts their trunk through the hole, a method previously used in chimps by Hare, Call and Tomasello (2006) and also in elephants by Nissani (2006).
It is predicted that the majority of African Elephants will significantly touch the silent container containing the sugarcane first in comparison to the noisy container so the competitor is unaware as demonstrated by Rhesus Macaque’s (Santos, 2008). If the African Elephants have a preference towards the silent container it demonstrates that these African Elephants can learn that if they pick the noisy container then their competitor are likely to hear and therefore fight for the food. Therefore, a ToM is demonstrated of the noises the competitor will hear.
In early ToM tests, African Elephants did not have Self-Recognition or ToM abilities, tested through looking at mirrors to locate hidden food (Povinelli, 1989). However, locating hiding food through a mirror is not a scenario an Elephants would be familiar with and therefore is confounded by high demand. In a similar, more familiar test African Elephants recently have demonstrated that they are able to recognise themselves separate from others through glow-in-the-dark marks, representative of marks used by zoos to differentiate Elephants (Plotnik 2006), suggesting that they have the basis for a ToM to develop. MacLean et al (2014) found that Elephants fail A-not-B tasks suggesting that Elephants do not have self-control. However, A-not-B was tested in a way unfamiliar for elephant behaviour, through watching food being moved from container A to container B, and then allowed to search. Therefore this proposed study would aim to challenge that Elephants do not have ToM though less demanding measures.
ToM has been suggested to have 2 levels (Flavell, Everett, Croft, & Flavell, 1981) the first level is where an animal must understand that something they can see someone else may not be able to (Povinelli 1989; MacLean et al 2014). Next there is Level 2 ToM, to reach this an animal must understand that the object they see./ hear may be viewed/ heard differently to someone else, a measurement of level 2 ToM is proposed in this study.
In Santos (2006), it was suggested that the Rhesus Macaque’ were scared of the noisy container, suggesting why they went for the silent container first. It needs to be further investigated whether this is true in African Elephants thus if they were selecting the silent container through fear of the noise or because they understood that the noise would draw attention to the “competitor”, a demonstration of ToM.
The study proposed here can also develop research in children and their Theory of Mind. In the last couple of decades, false-belief tasks have been argued to lack validity due to measurement and confounders of language abilities and Executive Functioning, (Bloom & German 2000). Therefore, using this auditory ToM task in children may further understanding of Level 2 ToM abilities in children.
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