Internet search engines like Google are changing the way our brains remember information, according to a new study that says readily available information online makes people easily forget facts since computers become their "external memory".

Researchers from Harvard University and Columbia University said Google and databases such as Amazon.com, IMDb.com serve as an external "memory, where information is stored collectively outside ourselves".

People are more likely to remember things they think they will not be able to find online and will have a harder time recalling information which they know they can easily access online, the study added.

"Since the advent of search engines, we are re-organising the way we remember things," Columbia University psychologist Betsy Sparrow said.

Our brains rely on the Internet for memory in much the same way they rely on the memory of a friend, family member or co-worker.

The research also found that people remembered where they stored their information or where to look for information on the internet better than they remembered the information itself.

In the paper titled "Google Effects on Memory: Consequences of Having Information at Our Fingertips," researchers conducted four experiments.

They gave students 40 statements, asking them to type the information on a computer.

Those who were told the information would be saved had a much harder time remembering the statements later than those who were told it would be erased.

Similarly, Columbia students were asked a series of questions and allowed to take notes.

The students who were told the information would be saved in one of six computer folders had a harder time remembering the information later than those who were told it would be erased.

About 60 Harvard students were asked to type trivia, such as "An ostrich's eye is bigger than its brain," into computers, and were told either the information would be saved or erased.

People who believed the data would be saved were less likely to remember, according to the study published online by the journal Science.

In the last experiment, Columbia undergraduates were told the same information would be saved in files with names such as 'facts', 'data' and 'names'.

The students remembered the file names better than the information itself, the study said.