A device the size of a sugar cube will be able to record and store high resolution video footage of every second of a human life within two decades, experts said yesterday.

Researchers said governments and societies must urgently debate the implications of the huge increases in computing power and the growing mass of information being collected on individuals.

Some fear that the advent of "human black boxes" combined with the extension of medical, financial and other digital records will lead to loss of privacy and a dramatic expansion of the nanny state.

Others highlight positive advances in medicine, education, crime prevention and the way history will be recorded.

Leading computer scientists, psychologists and neuroscientists gathered to debate these issues at Memories for Life, a conference held at the British Library yesterday...