NEW YORK: The use of adblocking software rose sharply in the final quarter of 2015 and industry leaders have highlighted the need to address the consumer concerns that are driving this trend.

Data from researcher GlobalWebIndex (GWI) showed a ten percentage point rise in internet users blocking ads on their main computer in the fourth quarter after little movement in the first three quarters of the year – from 28% to 38%.

"With the other privacy behaviours tracked by GWI showing little or no increase over the same period, it's clear that ad-blocking is the privacy behaviour in the ascendancy," it noted.

Last week, FTC Commissioner Julie Brill expressed surprise at the ad tech industry's lack of urgency in addressing these privacy concerns, "because it has always been the case that consumers could take matters into their own hands".

"Escalating a technology war with consumers isn't the answer," she told an Ad Exchanger event, and urged the industry "to explore the creation of innovative and usable tools to address consumer concerns about privacy.

"Not to find ways to work-around consumer choice, but to provide consumers with something they clearly want: to see advertising that respects their privacy and that they can trust."

Brill quoted a recent study that had shown 91% of people rejecting the idea that hidden or invisible data collection was justified by the offer of free or discounted content.

"I can't blame them," she said. "How can consumers knowingly bargain for free content without actually knowing what they are giving up, to whom and for what purpose?"

Data sourced from IAB, GlobalWebIndex, Ad Exchanger; additional content by Warc staff