Researchers concluded that the tools evaluated in the study, which included IE and Firefox components, were generally too complicated and confusing, leading people to misuse them.

"We found serious usability flaws in all nine tools we examined," reads the 38-page , released on Monday.

The nine tools fall into three main categories: tools that block access to advertising websites; tools that create cookies that indicate users want to opt out of behavioral advertising; and privacy tools built into web browsers.

The researchers enlisted 45 people to try out the tools. The participants weren't technical experts, nor were they knowledgeable about privacy tools, but did have an interest in this type of tools.

Each tool was tried out by five participants. Researchers observed how participants installed and configured the tools, and recorded the users' perceptions and opinions.