Aleks Krotoski asks if AI companions will be like imaginary friends of childhood? And if so will they afford the same benefits - making us better, more social human beings. To mark the 10th anniversary of The Digital Human we're answering some of the questions that have stuck with us over the last 10 years. In 2017 we spoke to Eugenia Kuyda she used her AI startup in San Francisco to help her create a chatbot version of her late friend Roman. Using all the texts she and her firends had ever received from him they made an AI that could text in voice. But its where she wanted to take the technology that intrigued us. She wanted give everyone their own Roman, an AI bot that would be a constant companion infinitely patient and understanding. It would be taught by the user using their own texts and so would speak to them in their own voice, she called it Replika. Five years on Replika has 20 million users across the globe. The idea made us instantly think of imaginary friends from childhood. In this programme Aleks sets out to find out if this more than an interesting metaphor but perhaps a key way to understand our relationship with these soon to be pervasive technologies. Producer: Peter McManus