The use of name based phone books in mobile phones has resulted in a sharp drop in the number of people who can dial a friend by recalling their phone number. A survey by phone backup service, CPP found that 47% of surveyed UK adults don't know their partners mobile number off by heart. In addition, 61% of respondents don't know their best friend's mobile phone number and 45% can't recall their parent's mobile number.

An online memory test, designed to assess the nation's ability to recall sequences of numbers, reveals that four in five Brits cannot recall a mobile phone number after an interlude of only five seconds.

Landline numbers it seems however, are more ingrained with 92 per cent of adults able to recall their home number and 60 per cent their parents'.

Mobile reliance is causing phone users to worry about losing precious data if their handset is lost or stolen, with nearly two thirds (67 per cent) anxious about losing the numbers stored on their phones. Despite this less than half of Brits (43 per cent) back up their mobile phone numbers in a traditional address book, and just one in five (18 per cent) choose to store the data on their computers.

Michael Lynch from CPP warns consumers though that there's much more at risk when losing a phone than just the data. "Brits' inability to recall numbers of their nearest and dearest means that many could be in a very tricky and distressing situation if their phone is lost or stolen, if they have no idea how to contact someone for help. This shows us that mobiles have literally become people's lifelines.

"Our research shows that people are so heavily reliant on their mobile phones, that they'd be lost without them. And even if not caught in an emergency situation, our research shows that four in 10 victims have admitted that they've lost contact with friends when they've lost or had their phones stolen."

The research showed that while losing phone numbers is mobile users' primary concern, four in 10 are also worried about losing precious photos taken on their handset and a third fear losing their text messages.

Psychologist Dr Glenn Wilson comments on the impact of us needing to remember less and less information: "As technology gets more sophisticated, our own memories are on the decline as we increasingly rely on information stored on phones and online. While this reliance can be problematic if people are totally dependent on an external memory store that is lost or becomes temporarily unavailable, it can also affect an individual's mental agility later in life. Like many other skills, memory needs exercising if the capacity is not to be lost."

Methodology

Research was carried out online by ResearchNow among 2,019 UK adults between 3 and 17 June 2010.