Blog Stroking, gentlyWhenever I find myself on a city farm (in Dutch: kinderboerderij), I often try to get the attention of the grazing cows. Often they turn their heads towards me just to go about their own business – chewing grass – a few seconds later. But occasionally and upon a gentle call – they come to me as if they understood my good intentions. Does it mean that cows can in fact perceive the interactions with humans as something positive? This study may give a clue. Cows as Pets The authors of this study were interested in whether repetitive and gentle interactions with humans make calves less afraid of them. They went to a commercial farm in Germany, and for the duration of 14 days, they pet newborn calves for 3 minutes each day. They stroked each calf on the ventral neck and talked to them with a soft soothing voice. The researcher first waited for a calf to approach her while talking to her gently, and in one third of the interactions the calves approached the researchers themselves. The majority of the calves allowed themselves to be stroked and showed signs of enjoyment. In almost 40% of all interactions, the calves stretched their neck towards the researcher – a sign of relaxation. They also licked the researchers during the interactions and showed play behavior such as jumping, which is a sign of positive emotions! The authors found it remarkable that calves played during the interactions, as it does not occur frequently among the cows. These observations confirm that cows do experience gentle interactions with a human as a positive experience. Stroked calves become less afraid But do these positive interactions make the calves less afraid of humans? When we experience something as positive or rewarding, we tend to approach it. For example, we would be drawn towards a playful and happy dog and would feel invited to have a chat with a smiling person. On the other hand – we avoid things and situations that we perceive as unpleasant or potentially painful. We would therefore intuitively step back when encountering a barking dog or a scary spider, which would be a sign of fear. The facial expression of others can also give us a clue about whether it’s safe for us to interact with that person. Indeed, we are more likely to be drawn towards someone smiling than someone who is looking daggers at us. Approaching positive and avoiding negative situations is absolutely essential for successful adaptation in the environment which is not only observed in humans, but across the whole animal kingdom. Also in cows. After 14 days of daily interactions with humans, the researchers tested whether the calves would avoid the researcher. The researcher individually approached the calf and extended her hand towards her nose. The distance at which the calf stepped back or drew her head in response to this gesture was used as a measure of fearful avoidance. If the researcher could touch the nose of the calf, the avoidance distance was estimated as 0 cm. Not surprisingly, the previously stroked calves showed less avoidance behavior compared to those who were not pet. Cows show less fear towards humans who have treated them gently! More than just economic gains Petted cows were also found to gain more weight. Especially those who received more milk, showed approximately 6.6% more daily weight gain compared to cows who did not experience gently interactions with humans. For farmers, it is important because higher weight gain is commonly associated with higher milk yield in later life, which is an important economic aspect. But there is something else to it. It shows that cows are able to learn and recognize what is good or bad for them. And similarly to us, they will avoid situations and humans whom they perceive as potentially dangerous or unpleasant. Despite appearances of passive grass-eaters, cows will remember your soothing voice and kindness. And next time – when you gently call them on a city farm – they will come to you, trusting your kindness. Picture from ivabalk via Pixabay... Transfer of emotional states between pigsTypical for humans is that we often ‘feel’ the emotional state of another. When a mother witness her baby crying, she feel also upset too, and when we watch a movie with a happy ending, we also empathize with the main characters. In psychology, experiencing of emotion in one individual upon witnessing it in another individual is called emotional contagion.1 Interestingly, we do not only share a conscious experience of feeling happy or sad, but other bodily responses such as changes in heart rate or even blushing, have also been proposed to to transfer from one person to another during a social interaction.3 Why is the transfer of emotions between individuals important? Emotional contagion is an automatic response which is considered to be the simplest for of empathy. We feel more empathic towards individuals we are familiar with and with whom we are socially closed than with strangers.5 The matching of our emotional state with that of another often makes us help them. Because the mother feels for her crying baby, she understand that the baby is upset and needs taking care of (e.g., changing a diaper). If we feel sorry for the situation of a homeless person, we will support them financially. Emotional contagion is therefore a building block for more complex social behaviors, and observed not only in humans, but also in non-human animals such as dogs and great apes.4 Recent evidence suggests that pigs can also experience each other’s emotions. In one study, a pair of pigs were guided either to a rewarding or aversive chamber. In the rewarding chamber, there was plenty of straw, peat and hidden raisins which pigs could freely explore together. In contrary, the pair of pigs were separated before being guided to the aversive chambers where each of them were restrained to increase the unpleasantness from being separated. Before entering each of the chambers, the pigs spent some time in a so-called starting chamber in which different sounds and visual information were shown to the pigs so that they could learn to predict which chamber they subsequently enter. In the rewarding chamber, the pigs were playing in the straw: they were running and pivoting with straw by shaking their heads, they were barking (check out how pigs bark here), and wagging their tails. All these behaviors are associated with positive emotions. Pigs in the aversive chamber, on the other hand, showed more freezing, high pitched vocalizations, attempts to escape, defecating and urinating. They were also grunting more (which are thought to be a sign of social contact calls), showed more ears back and their movement from front to back as well as more tail low (similarly to dogs). In pigs, a default tail position is a tail in curl from which other tail positions – wiggling tail or tail low – can emerge if they experience positive or negative emotions, as the authors imply. Interestingly, when presented only with the cues predicting the rewarding and aversive events in the starting chamber, the pigs also displayed behavior suggestive of positive and negative emotions. They nosed the doors of the rewarding chamber but oriented their heads more towards the aversive chamber, and showed more ears back and their movement back and forth (vigilance) suggesting that they knew what was going to happen. After demonstrating that pigs can indeed show (anticipatory) emotional responses to rewarding and aversive events, the authors were interested in whether these responses can be also observed in new pigs who joined them in the starting chamber. The new pigs have never experienced the above procedures before and if they show behaviors suggesting of negative or positive emotions, that would suggest emotional contagion. As expected, during a rewarding cue and event, the new pigs showed more curly tail and more playful behavior suggesting the presence of positive emotions. In the contrary, the new pigs showed more tail low and more defecating compared to the rewarding event, indicating that they were stressed. The researchers remarked that these behaviors cannot be due to simply due to copying because low tail was not displayed by the initial pigs in the starting chamber. This study suggest that pigs – similarly to dogs and primates with more complex social interactions – also show emotional contagion and are likely to experience positive or negative emotional states displayed by their companions. This implies that on animal farms – where pigs are often kept in large groups together, unpleasant or harmful procedures performed on individual pigs such as handling (catching pigs) or tail docking, are likely to cause stress in other present pigs. References:1Hatfield, E., Cacioppo, J. T., & Rapson, R. L. (1993). Emotional contagion. Current Directions in Psychological Science: 2(3), 96–99. doi: 10.1111/1467-8721.ep107709532Reimert, I., Bolhuis, J.E., Kemp, B., Rodenburg, T.B. (2013). Indicators of positive and negative emotions and emotional contagion in pigs. Physiol Behav 109:42-50. doi: 10.1016/j.physbeh.2012.11.002. 3Prochazkova, E., Kret, M.E. (2017). Connecting minds and sharing emotions through mimicry: a neurocognitive model of emotional contagion. Neurosci Biobehav Rev 80: 99-114. doi: 10.1016/j.neubiorev.2017.05.013. 4Marino, L., & Colvin, C. M. (2015). Thinking pigs: A comparative review of cognition, emotion, and personality in Sus domesticus. International Journal of Comparative Psychology, 28, Article 23859.5De Waal, F.B. (2008) Putting the Altruism Back into Altruism The Evolution of Empathy. Annual Review of Psychology: 59, 279-300. doi: 10.1146/annurev.psych.59.103006.093625... Chickens remember hidden objectsIn this series of blogs, we will discover that chickens demonstrate many cognitive abilities and skills that we would never attribute to them in the first place. Did you know that chickens – similarly to many other birds – are able to track occluded objects, a skill that infants also acquire during their first months of life! Or that they show similar physiological responses to dangerous stimuli as humans, such as reduced heart rate? Even more interesting is the fact they chickens can memorize and recognize individuals in their surroundings!1 Let’s start with perception and short-term memory. In psychology, short-term memory refers to memory that we use to store information for a limited period of time. We use it in everyday situations, for example when you temporarily store a phone number in your mind to dial it a few seconds later. Now, although this ability appears to be very basic and easy to perform, we humans develop a very simple form of working memory only around the age of one. It was one of the discoveries that made psychologist Jean Piaget famous. In the eighties, Piaget proposed that infants aged 8-12 months develop an understanding that an object exists even if it’s not visible. This early form of working memory (called object permanence) is observed when an infant removes a cover from your face during a peekaboo game, or removes a blanket covering their favorite toy. This stage of development follows a simpler skill when an infant reaches not for fully but only partially hidden object.2 Do chickens show similar skills? To find out the answer, researchers have performed a similar occluding experiment with the new born chicks. The chicks were first imprinted into geometric shape such as a red triangle to which they have become accustomed to. Next, the researchers presented a chick with either a partially hidden red triangle on the one side, and a triangle with a missing piece as a control on the other side. The chicks choose to be near a hidden imprinted triangle, which suggests that – similarly to humans – chicken’s visual system fills in the part of occluded object, allowing them perceiving it as a whole.3 In yet another study, the researchers were interested whether the chicks would follow the location of the familiar object if it was totally hidden. As in the previous experiment, the chicks were first familiarize with a small object. Subsequently, the chicks were shown the object disappearing behind one of the two identical screens and were allowed to follow it, which in most of the cases they did. So the chicks learned that they can find their favorite objects behind one of the straight screens. In the final phase of the experiment, the object was again moving towards one of the two screens and when it was half way, the chick’s view of the object was blocked. During this time, the slant of one of the screens was changed, and after the partition blocking the view of the chicks was removed, they could again decide where to go. The dominant behavior of the chicks as to walk towards the unchanged – straight screen, where they would have previously found the familiar object. These studies suggest that chickens can recognize partially hidden objects and even remember their location if they are fully hidden. This is particularly the case for items with whom the chicks created a social bond (e.g., during the first days of life). References: 1Marino, L. (1997). Thinking chickens: a review of cognition, emotion, and behavior in the domestic chicken. Anim Cogn: 20(2): 127-147. 2Piaget, J. (1954). The construction of reality in the child. London: Routledge and Kegan Paul. 3Regolin L, Vallortigara GPercept Psychophys. (1995). Perception of partly occluded objects by young chicks. Percept Psychophys: 7(7):971-6.4 Chandetti, C., Vallortigara, G. (2011). Intuitive physical reasoning about occluded objects by inexperienced chicks. Proc Biol Sci: 278(1718): 2621:27. Image credits: Chick: Animals vector created by terdpongvector – www.freepik.comGrass: Summer vector created by macrovector – www.freepik.comBall: Banner vector created by pch.vector – www.freepik.com...
