An investigation of socially-mediated emotional transfer in the chicken

To ensure good animal welfare we need to identify, and then take steps to alleviate, causes of possible distress. Much research has focussed directly on physical, environmental and social situations that are distressing to laboratory or farm animals. Our proposed research takes a different angle and addresses the possibiity that animals might additionally experience distress when their own situation is good, but when they witness distress in others. In its most advanced form, this capacity might be called empathy, implying that the witness understands the reasons for its companion's distress. In humans, and perhaps great apes, such advanced abilities to understand the plight of another may promote positive social behaviour or "helping". However, the roots of empathy probably lie in a set of much simpler, building block, processes. One of these building blocks is emotional matching, also called emotional transfer or emotional contagion. These terms refer to situations where physiological or behavioural signs of distress in one animal to trigger a shared or matching response in an observer. In human infants emotional transfer is shown when the crying of one baby produces a similar crying response in others nearby.

Our recent work has shown that, under some circumstances, chickens show this type of emotional transfer. We found that mother hens react strongly and consistently (with changes in heart-rate, comb-temperature, vocalisations and other behavioural changes) when their chicks receive a mild air-puff. The aim of this research is to discover much more about the situations under which this emotional transfer takes place in chickens. The research will be useful in clarifying a field of research where results can often be over-interpreted and advanced abilities claimed when they may not really exist. But the research also has important animal welfare implications. If animals are upset by seeing distress in others this may guide our veterinary, transport or even slaughter practices. It is also possible that animals in a poor state of welfare are more likely to show emotional transfer, leading to harmful outbreaks of group panic.

We will address a number of fundamental questions in small-scale experiments with chickens:
- does the observing hen find it unpleasant to witness distress in her chicks?
- does emotional transfer occur when the observing hen is in a good emotional state herself, and when she "knows" she is in no personal danger?
- does emotional transfer help the observing hen to acquire important information about pleasant and unpleasant situations?
- to what extent does emotional transfer depend on the strength of the social relationship between the observing hen and the individual (chick or adult chicken) that receives the mildly unpleasant stimulus?
- is emotional transfer more likely if a hen is in a poor welfare state?

Taken together these studies will shed new light on the extent to which non-primate animals may share emotions. Although our laboratory studies will not directly inform policy decision on animal handling, transport or slaughter, the results will be highly relevant to these areas, and will therefore provide a platform for more applied studies on farms, laboratories and abattoirs.

A conspecific observer that witnesses signs of pain or distress in another may experience an empathic emotional reaction. The word empathy refers to the vicarious transfer of emotion, but is often bound together with high level concepts such as theory of mind, and altruism. Often different levels of explanation are not differentiated in observational or experimental studies.

We have established a model whereby hens reliably show emotional transfer, responding to the mild distress of their chicks with a suite of subtle behavioural and physiological changes, detected using sensitive non-invasive recording methods. We now propose to establish the contexts, welfare consequences, and functional benefits of this emotional transfer. By so doing we will identify empathic processes that may be general to many vertebrate species, and which are likely to underpin the more complex abilities of primates and humans.

We will use place preference and other established techniques to establish whether emotional transfer is accompanied by aversion, rather than simply reflecting arousal. We will examine whether either prior emotional state, or the degree of perceived personal safety, influences the extent to which emotional transfer occurs, and whether there are any functional benefits of emotional transfer to the observer (we predict it may facilitate social aversion learning) or the demonstrator(s) (via social buffering). We will also examine how the nature and strength of the social bond between observer and demonstrator influence the degree of emotional transfer that takes place. Finally we will investigate whether the long-term welfare state of the observer influences emotional transfer.

In addition to adding to fundamental knowledge, the proposed research has direct relevance for animal welfare as little is known about whether or how distress is transmitted between farm or laboratory animals.

The following are potential non-academic beneficiaries of our research.

1. Chickens. By establishing the contexts in which chickens may share mostly negative emotions we will be able to use this work as a platform for more applied investigations of the real-world impact. For example, although it takes only a few seconds to catch one chicken, it takes many hours to clear a house containing between 5000 to 50000 birds. Chickens are also loaded, shackled and stunned in sight of each other. It is even possible that the damage and injuries that chickens commonly sustain in farming systems (keel fractures affect an average of 60% of hens; up to 25% of broiler chickens can experience lameness) have some impact on their companions. None of these possibilities can be investigated without fundamental information.
2. The laying hen industry. Emotional transfer may underlie some of the common problems experienced in non-cage laying hen systems e.g. outbreaks of group panic, "hysteria" and smothering, which result in mortality and economic losses.
3. Policy makers. Policy-makers in government and government agencies (e.g. Defra and Animal Health) responsible for producing Codes of Recommendations, inspecting farms and implementing animal welfare law already seek information in this area. For example, in 2005 Defra issued a call asking for research on whether mares should be slaughtered in sight of their foals. Without any fundamental knowledge in the area it was not possible to prepare an answer to this emotive issue.
4. Animal welfare organisations such as the RSPCA and Compassion in World Farming are extremely interested in the basic cognitive and emotional capacities of farm animals. CIWF, for example, devotes a substantial proportion of its webpages to questions of farm animal sentience see: http://www.ciwf.org.uk/animal_sentience/default.aspx. They constantly seek out and translate to a broader audience scientific evidence relating to farm animals' "intelligence and emotions". Their webpage even states that there is evidence that some animals "appear to show emotions similar to human empathy".
5. The public also has a seemingly insatiable demand for information about the intelligence and emotional lives of farm animals. We have been very actively involved in public engagement activities, giving well-received talks on "Farm Animal Minds" and "Animal Sentience", as well as contributing to programmes such as the BBC Secret Life of Farm Animals (2010) and the One Show (2011) which explored these capacities in chickens. This information informs the UK public and may guide their decisions about what types of animal products they wish to purchase, at what price. We have standing invitations from some media shows to contact them if we make interesting discoveries about chicken behaviour or cognition, and it would be our plan to do so as soon as we are sure we have robust results.