IT professionals and chief executives were among the 130 people who disclosed the information while answering questions on their attitude to computer security.
The majority of people where happy to hand over their passwords straight away, while others accidentally disclosed it during further questioning.
One businessman told the interviewer, "I am the CEO, I will not give you my password, it could compromise my company's information." But he later went on to reveal it was his daughter's name. "What's your daughter called?" the interviewer asked. "Tasmin," he replied.
The most popular password was "password", followed by first names, football teams and dates of birth - items that can be easily guessed by hackers.
The research, by Infosecurity Europe, suggests that few staff understand the importance of good password management. Sixty six per cent have given their passwords to colleagues. The same proportion use the same password for everything, including personal banking.
Infosecurity Show, 29 April to 1 May