Social media websites are increasingly becoming forums for people to stand up for what they believe in but can often lead to regrets over pressing the "send" button too quickly, according to research.

More than half (55%) of the 2,000 people surveyed said that they felt social media had replaced face-to-face interaction, and nearly two in five (39%) people said they used social media to speak up about something they felt passionate about.

Of these 39%, nearly half (44%) believed what they said had made a difference, and led to people blogging or tweeting about the issue, or actual changes being made.

Social media is not without its pitfalls though, according to the independent research carried out on behalf of the Holocaust Memorial Day Trust and released today to mark Holocaust Memorial Day.

More than a quarter (26%) admitted they would say, or have said, something on a social media website they would never say to someone's face.

A quarter of those surveyed also said they had regretted putting something on a social media site. Some 44% of those regretted it because what they said had been inappropriate, while 27% regretted it because they thought it had upset someone.

The findings, analysed by Robin Dunbar, Professor of Evolutionary Anthropology, Fellow of Magdalen College, Oxford, also revealed that online bullying was a serious problem, with more than a third (36%) of respondents having witnessed or been a victim of online bullying.

Some 41% of these people said they had intervened directly in such cases, while nearly 25% of people who had witnessed such bullying said they had done nothing at all.

Professor Dunbar said: "Our research has shown that people are more prone to saying something on social media that they later regret, because in these digital environments we don't receive the immediate checks and balances that we get during face-to-face interactions.

"This can therefore result in a careless or inappropriate tweet, or at worst, cyber bullying."

The theme of this year's Holocaust Memorial Day is Speak Up, Speak Out and the Holocaust Memorial Day Trust is asking people to consider what they see and hear around them, and to use their voices to speak up against hatred and discrimination.