This data set contains data collected from 21 infants and their mothers, using behavioural and physiological measurement. The experiment aimed to investigate shared body representations between a mother and her infant, and consisted of two main tasks. The first, the Mother-Infant Bodily Overlap (MIBO) task, was designed to measure the extent to which an infant ‘shared’ in the tactile experiences of their mother. The task carried out with the infants took the form of a preferential looking paradigm. For each trial, infants were shown two side-by-side videos, both featuring either their mother, or an unfamiliar woman, being stroked on the cheek. The infant’s own cheek was stroked by an experimenter, in synchrony with the touch seen in one of the videos and out-of-synchrony with the touch seen in the other video. Looking times were coded to the two videos. The second task investigated the extent to which mothers shared the emotional experiences of their infant. We measured automatic facial mimicry using electromyography (EMG) recorded from the corrugator and zygomaticus muscles, whilst mothers were observing emotional expressions recorded from their infant, or from an unfamiliar infant. We also asked mothers to indicate after each video their subjective emotional experience during the expression, using a 2-dimentional Visual Analogue Scale upon which mothers rated their valence and arousal. Two other data collections have been created for this grant, Part 1 and Part 2. These can be accessed via Related Resources. Humans are fundamentally social animals. We form close relationships with others and characteristically live in small, close social groups of siblings, romantic partners, and our infants. Social psychologists have shown that the way in which we process social information from our family members and intimate partners is very different to that from strangers and acquaintances. For example, we show increased empathy when our intimate partners are in pain, mothers have enhanced detection of their own infant's cries, and we show enhanced altruism and trust for our siblings. Evolutionary psychologists argue that these distinct social behaviors serve important biological functions, such as long-term pair-bonding, child-rearing, and maintenance of kin-relationships. In evolutionary history, these processes were central to survival and reproduction. They argue that much of our social behavior in the present day still serves these functional relationships, often on an implicit level. Therefore, evolutionary psychology has provided an explanation of why these special social processes exist, appealing to their specific biological functions. However, no-one has yet provided an explanation of how we are able to process social signals from our close family and partners in this special way. We suggest that a focus on the role of the body in social cognition may enable us to understand the neurocognitive basis of these evolutionarily important social processes. The way we represent our bodies and the bodies of others plays a central role in our understanding of social signals. Evidence suggests that when we observe the bodily experiences of others, such as touch, pain, emotion and movement, we 'share' these experiences. For example, when we see someone being touched, specific areas of our brains are activated in the same way as if we were touched ourselves. This sharing of others' bodily states, also known as 'bodily overlap', might underlie a number of important social processes, such as empathy, emotion recognition, and understanding others' intentions. So far, experiments investigating this bodily overlap have only used unfamiliar others as social stimuli, and so our understanding of the role of the body in social processing is restricted to how we interact with strangers. This neglects significant others, such as family and partners. Can differences in the way we represent their bodies in relation to our own explain the enhanced empathy we have for a partner, the increased trustworthiness we see in a sibling's face, or the special ability of a mother to read her infant's emotions and needs? And if we change bodily overlap, can this affect the quality of our relationships with close others? This project will investigate the role of bodily overlap for social cognition in biologically important social relationships, focusing on relationships between siblings, mothers and infants, and partners. For each relationship, we will use a variety of experimental methods to assess bodily overlap and social processing. We will also experimentally increase bodily overlap between individuals, and see how it changes perceived relationship quality. The results of our research may have a number of diverse applications. One area which our research might impact upon is that of health and well-being. The physical and mental health benefits of close relationships and the adverse effects of family breakdown are well documented. Our research will investigate the effects of increasing bodily overlap within these relationships to improve relationship quality, and this makes our research very relevant to relationship therapies and other family interventions. We also foresee a number of applications in other areas, including the work-place, whereby our research into close adult relationships could be extended to increase our understanding of the role of the body in creating and maintaining functional and productive relationships between work colleagues.

Infant looking time data were collected by video recording the faces of 21 infants during completion of the MIBO behavioural task. Offline, two trained raters coded each video for fixations on the left or right of the computer screen for each trial. The number of trials the infants completed varied, and depended on attention levels and fussiness. Mother mimicry data were collected by EMG recording, whereby two pairs of AgCl electrodes were attached to corrugator and zygomaticus muscles on the left side of the face. Muscle activity was continuously recorded whilst mothers observed 3-second long videos of infants making facial expressions. Mothers' subjective experiences were also recorded, via mouse button-press on a Visual Analogue scale.