The survey of 4000 Americans and Canadians reveals that millennials and high earners (those with a household income of at least $150,000) are the most avid adopters, with more than half of both groups using their handsets as payment devices.

Of the 60% of respondents that have never used their mobile phones as payment devices in a merchant location, 57% cite security and 45% privacy as the factors holding them back.

Some people are not just embracing new payment methods but new currencies: eight per cent use new options such as bitcoin at least once a week, and 18% expect to use them by 2020. Again, millennials and high earners are driving adoption, with protection of personal identity and lower transaction costs cited as key attractions.

Whether they use mobile payments and digital currencies or not, North Americans seem confident that there will be a decline in the use of more traditional methods like cash and cards.

Today, 66% of respondents say they make cash transactions, 59% use debit cards and 55% use credit cards at least weekly. But asked how they anticipate using these instruments in 2020, people say they will probably be less likely to use them at least weekly - particularly when it comes to cash.

Matthew Friend, MD and head of Accenture Payment Services in North America, says: "By 2020, we anticipate the first decline in credit card usage in more than five decades and in debit card usage since they were introduced.

"While millennials and higher income consumers are paving the way for increased mobile payments and the usage of digital currencies, we expect the other age groups to increasingly embrace these payment methods as more consumer friendly and secure solutions become available in addition to merchants adopting these technologies."