The development of own-body representation in childhood.

Perceiving one's own body is crucial for being able to perceive the world and act on it. But how do we do this? Imagine that I can see two hands resting on the table in front of me. One is mine, and one belongs to my friend. How do I tell which is which? This seems like an obvious question, but on consideration it is not. In fact, research has told us that adults use several different types of information, including multisensory visual, tactile, and movement cues; and stored knowledge about the form of their own hand. A more difficult question is how children manage to identify their own bodies in the midst of the constant growth and change which occurs in childhood. Very little is known about this. In particular, it is unclear how children balance the need for a consistent idea of their own body, and the need to be flexible as it grows. Further, new virtual reality technologies are emerging which can provide virtual bodies to children in games or educational settings. How might children accept and use these virtual bodies?

This 3-year project addresses these issues by investigating how children and adults perceive their own bodies, and how this grounds the emerging sense of bodily self. We will run five carefully designed experiments, building on methods which we have previously used successfully with children. The project team have the theoretical and technical backgrounds necessary to carry out this pioneering work; our lab has suitable equipment; and the proposal includes previous published and pilot data showing the feasibility of the approach.

We will experimentally examine own-body representation using the 'Rubber Hand Illusion'. The participant sees a fake hand on the table in front of them while their real hand is hidden. An experimenter strokes the hands at the same time. This makes the participant feel as if the fake hand is their own. Further, when asked to point underneath their own hand, they point near the fake hand. We have recently shown that 4 - 13-year-old children experience this illusion. Here, we will measure what happens when the size or shape of the fake hand is changed. If participants experience the illusion less in these cases, it shows that they have expectations for how their hand should look. Based on previous work, Experiments 1 and 2 will test the hypotheses that both children and adults will expect that a hand must be five-fingered; and that the hand must be approximately the right size. Crucially we will also determine whether there is plasticity in these body representations, enabling children to accept for example larger hands than their own to account for growth. Experiments 3-5 will examine how body representation may change given experience of a moving body. Do children learn more quickly from experience more than adults, for example requiring less movement experience to accept an oversized hand? How does touch information combined with movement in forming a sense of the bodily self? What are the limits of what children will accept as their own body in such an environment?

The academic outputs of the project will provide vital new information on how children represent their bodies. This is an interdisciplinary project between Psychology and Computer Science, and its findings will be of major significance and interest across a range of disciplines - Psychology, Computer Science, Philosophy, and Cognitive Science. The work will also have non-academic impact. We will communicate findings to designers of virtual reality games, as well as healthcare practitioners developing bionic arms or using virtual rehabilitation programmes. Finally we will use the work as a springboard to invite volunteer children to a series of workshops examining the senses and movement. Through these we hope to encourage them towards STEM activities or careers.

We believe that the work from this grant has excellent potential to generate impact across a range of areas - from public engagement with science, to rehabilitation schemes and the videogames industry. Careful consideration is given to our impact plans, which are laid out below and in the Pathways to Impact document. The impact work will be further enhanced by the fact, with a drive towards creating Case Studies for REF, impact activities are strongly supported within the Durham Psychology Department. The beneficiaries of the work will be as follows:

Producers and designers of games and virtual environments: There is an increasing use of virtual reality environments in which the user inhabits a virtual body. Children are important users of such games. This raises crucial design questions of how closely virtual bodies have to be customized to the child, and what the characteristics of these virtual bodies should be. Further, it will be important for designers to understand how recent technologies such as motion tracking impact virtual body acceptance in children. Our work will have an impact by providing some of the first direct answers to these questions. We will achieve this impact by providing guidelines that will help create better virtual bodies for children, and disseminating these widely. Dissemination will be achieved first through attending industry conferences. Second, we will produce a short film and documentation, and publicise these heavily on industry blogs and websites. Website statistics, as well as direct feedback from users, will be used to measure the impact that we achieve.

Healthcare practitioners: As described above, the grant will measure how the form of a virtual body and the technology with which it is presented impact on its acceptance. This has two potential healthcare applications. (1) Virtual reality is increasingly used for motor rehabilitation, for example for children with Cerebral Palsy. We aim to generate knowledge which will impact upon the design of these VR motor rehabilitation environments, ensuring that users are well engaged, with a good acceptance of their virtual body. For example, how much movement practice is necessary to start feeling acceptance of a virtual hand? To achieve this impact we will communicate with groups such as CerebralPalsy.org.uk, working to raise awareness of our findings. (2) There has been significant recent progress in producing bionic arms for children. The company Open Bionics makes a range of children's bionic hands, some with non-human textures and colours. They have agreed to engage with us in understanding how our findings might help them design hands which are attractive to children, but also easily accepted as part of the child's own body.

Volunteer families: From our experience, our child participants are highly interested in issues such as how they recognise their own hands or feet, or how physical growth might change their perspective on the world. We will therefore communicate our findings on body representation to the children who take part in our research. This will have an impact by engaging parents and children with science and encouraging children to pursue STEM careers. To generate this impact, we will provide regular information on our project through lab webpages and through newsletters sent out to the ~600 children on our volunteer database. Website statistics will be monitored as a measure of impact. We will further organise a series of special workshops held in schools and in our lab. In these, children will take part in fun demonstrations which engage them in the issues we are studying. Children taking part in these events will complete short surveys to enable us to measure their impact.