The study of more than 1,500 consumers across Europe also found that only 18% of users pay attention to ads when browsing a portal.
However, over 60% of respondents were found to pay attention to an ad when browsing an ecommerce site looking for a specific item to buy.
When asked what types of online advertising prompts them to part with their cash and make a purchase online, people gave the biggest positive response (38%) to listings on search engines.
In contrast, video performed relatively poorly, with only 7% of UK shoppers claiming a video ad had prompted them to buy a product or service in the last six months.
Pop-up ads were the least popular of all, with only 6% of shoppers admitting to have chosen a product or service to buy as a direct result of viewing this type of advertising.
Phillip Rinn, director of advertising partnerships for eBay UK and EMEA, said: "The results of our study reveal some interesting trends in consumer shopping behaviour and just go to show that if you're a brand selling a product, it's even more crucial in a tough economy to make sure your precious advertising budget is geared towards targeting consumers who are most likely to buy.
"Brand advertisers have two choices: follow the 'catch all' route of placing ads on the broad portal sites and social networks, where awareness may be high, but conversion to purchase low; or opt for a more targeted approach of reaching transaction-minded consumers who are already in the search and buy flow."
Rinn added: "As consumer wallets feel the pinch, brand advertisers should look carefully at how they allocate their online spend, in order to maximise their marketing budgets."