Elsevier

Applied Animal Behaviour Science

Volume 209, December 2018, Pages 47-54
Applied Animal Behaviour Science

Social learning in horses: The effect of using a group leader demonstrator on the performance of familiar conspecifics in a detour task

https://doi.org/10.1016/j.applanim.2018.08.015Get rights and content

Highlights

  • We examined equine social learning in a detour task with the group leader as the demonstrator.

  • We refined previous studies by using non observer and social facilitation controls.

  • Our results show a significant role of social facilitation unrelated to learning.

  • We found no evidence for higher level learning processes.

  • Simple mechanisms could account for much complex social behaviour in horses.

Abstract

Learning through the observation of others allows the transfer of information without the costs incurred during individual trial and error learning. Horses (Equus caballus) are a highly social species, which might be expected to be capable of learning from others, but experimental findings are inconsistent, and potentially confounded by social facilitation effects not related directly to the learning of the task. We refined the methods used in previous equine social learning studies, to examine and distinguish specific social influences on learning of a task: we used predefined group leaders rather than agonistically dominant individuals to demonstrate a detour task to familiar conspecific observers; in addition we had two control groups: a non-observer (true control) and a group with the demonstrator simply present at the goal (social facilitation control). 44 socially kept horses were allocated to one of the three test conditions and took part in five trials each. Success rate, latency and detour direction were recorded. There was no significant difference between the three groups in the likelihood of them succeeding in the task nor latency to succeed; however there was a significant difference in the route chosen by the groups, with the true control choosing the side with the entrance gate significantly more than either the observer group or social facilitation group. Both of the latter two groups chose to go in the same direction relative to themselves, regardless of which side the gate was. Seven out of nine horses in the observer group chose the same direction as their demonstrator every time. Our results show a significant role of social facilitation on detour behaviour and highlight the importance of including adequate controls for simpler cognitive influences on behaviour before claims can be made about the specific learning of motor actions or goal directed behaviour. Social cues may be important to horses if the task is sufficiently challenging and motivationally important, so future work should consider more demanding, but ecologically relevant situations, in order to maximise the potential revelation of social learning effects which do not depend on simple local or stimulus enhancement effects.

Introduction

Learning through the observation of others takes many forms, but enables the individual to gain valuable information about the environment and acquire new skills or resources, without the costs entailed with direct experience. The horse is a highly social species, in which it appears extremely difficult to show clear learning of specific behaviours through social learning effects (“imitation” or R-S learning, sensu Heyes, 1994) or goal emulation (the copying of the results of actions sensu Tomasello, 1990) (Nicol, 2002; Murphy and Arkins, 2007; Brubaker and Udell, 2016). Despite this, there remains a strong belief that horses should be capable of these forms of social learning amongst both scientists (Krueger et al., 2014a) and owners (Nicol, 2002); indeed, amongst owners, this belief has serious implications for the well-being of captive horses as it often results in the isolation of horses showing stereotypic behaviour, like weaving, due to fears that the behaviour might be “copied”, to the detriment of the isolated horses’ welfare (Cooper and McGreevy, 2002).

Experiments designed to investigate social learning in horses typically involve training a demonstrator animal to successfully complete a task. Generally, evidence of observational (social) learning is obtained when naïve conspecifics (observers), complete the task more successfully than control animals who did not watch the demonstrator. A number of studies have failed to find a significant effect of social learning, despite employing both discrimination tasks (Baer et al., 1983; Baker and Crawford, 1986; Clarke et al., 1996) and operant devices (Lindberg et al., 1999; Ahrendt et al., 2012). Krueger et al. (2014a) reported that young, low-ranking and more explorative horses learned to operate a feeding apparatus by observing older group members. Rørvang et al. (2015a) have noted several limitations to this study, including inadequate controls and the possibility that learning could have been through individual trial and error and not socially mediated.

Detour tasks have been used to demonstrate social learning in a range of species (e.g. dogs: Pongrácz et al., 2001, 2003a,b, 2005; tortoises: Wilkinson et al., 2010) and may present a viable solution to examining social learning in horses. Two previous studies have used this approach in horses, both using a dominant demonstrator, and they found no evidence of observational learning (Dalla Costa et al., 2013; Rørvang et al., 2015a). However, dominance relates to the ability to take precedence for access to a resource and so may not be the most useful characteristic for a demonstrator in social learning tasks. Further, dominance does not necessarily correlate with leadership (e.g. in feral dogs: Bonanni et al., 2010; cattle: Della Rossa et al., 2013) and leadership is associated with a variety of socially important factors, including affiliative relationships (baboons: King et al., 2008), physiological state (lactating zebra: Fischhoff et al., 2007) and experience (Reebs, 2010). Thus, leadership status may be an important variable affecting demonstrator significance in a social learning context.

Many studies have investigated leadership in grazing mammals (sheep: Squires and Daws, 1975; cattle: Sato, 1982; Šárová et al., 2010; zebra: Fischhoff et al., 2007), including caballine horses (Bourjade et al., 2015). Sato (1982) defined three types of leadership in herbivores; movement leadership, the initiation of activities (e.g. resting), and leadership during actual grazing. In the context of social learning different types of leadership might be important depending on the task being demonstrated, for example in the case of a detour task ‘movement leadership’ may be most important; i.e. the individual who tends to successfully initiate movement of one or more followers to (i) drinking, (ii) sheltering or (iii) new grazing sites; since the task requires an observer to move from a starting point ‘X’ to a goal located behind a transparent barrier, moving away from the desired goal in order to attain it (Zucca et al., 2005).

Many experiments designed to demonstrate more complex forms of social learning fail to control for simpler forms of social influence (Heyes, 1994). This includes (i) social facilitation, where the mere presence of an individual acts to either increase motivation or reduce fear, thus increasing the likelihood of observers learning a similar act and (ii) stimulus or local enhancement, where the activity of the demonstrator draws the attention of the observer to a particular object or location associated with reinforcement opportunities. For example, Schuetz et al. (2017) examined interspecific social learning between horses and humans using an operant feeding device, and found that the observer group had significantly higher success rates than the control group, however, a lack of controls make it unclear what mechanisms controlled this behaviour.

We therefore examined social learning in familiar horses living in stable social groups using a detour task, accounting for the aforementioned issues through the use of a socially relevant leader as demonstrator, the provision of two feeding stations to reduce the risk of agonistic encounters and both a true control (non-observer group) as per Dalla Costa et al. (2013) and a social facilitation control as per Rørvang et al. (2015a).

Section snippets

Method

The research was approved by the delegated authority of the University of Lincoln Research Ethics Committee.

Leadership

Leadership events were easily recorded due to the weather conditions, which meant horses frequented the water trough and shelter from the sun on multiple occasions. Both Bands 1 and 2 had a single horse with the highest possible leadership score of one (Tulip and Primrose respectively), meaning that they were always leaders and never followers. These horses were chosen as demonstrator for the detour task (Table 1). Band 3 had three horses with a leadership score of one (Fayre, Elm and

Discussion

Our results revealed evidence of the importance of social facilitation in shaping the responses of horses. They add to the growing body of evidence which indicates that more complex social learning in horses, if it occurs at all, is not a widespread phenomenon. However, simpler mechanisms that appear to underlie horse social learning may occur widely and could account for much complex social behaviour observed in horses (Table 2).

Our results show that the presence of a conspecific engaged in

Conclusions

This study set out to further investigate social learning in the horse, a highly social species. Our results indicate that the mere presence of this demonstrator alters subjects’ detour behaviour. Thus it is imperative that crucial controls are included in future social learning studies to allow investigation of the process underlying this behaviour. This is particularly relevant when considering sophisticated social learning mechanisms. Although there is great interest in the degree to which

Conflicts of interest

The authors declare that they have no conflicts of interest.

Acknowledgements

We thank Redwings Horse Sanctuary for kindly allowing their horses to participate in this study and their staff for assistance with data collection.

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