Tuesday, 18 December 2018

Using performance to manipulate behaviour

A darker side to the performance story seems to be emerging. This is the first in a series of 3 posts (there might be more later) about how web performance is being weaponized.

While I, like many of you, spend a lot of time simply trying to make my sites going faster, it seems that other people at finding ways to exploit performance as a way of manipulating user behaviour. This was particularly evident when I recently visited www.forbes.com to read an article about phone biometrics. Not where I would go to for authoritative information – I was just browsing at the time. As is common, it asked me if I wanted to accept its cookies.



Yes, they want to protect their revenue stream so the big green button with white text is easy to see and read, while the smaller grey button is a lot harder to read – and only professes to providing “more information”. Now due to the specifics of the EU's GDPR act, the site needs my “informed consent” to any cookies it drops – so not surprisingly the “more information” button takes me to a dialogue where I can also specify which cookies I will accept.


If I click on the first, big green button, I get an almost immediate acknowledgement. Accepting all three classes of cookies from the “more information” dialogue seems to take slightly longer, but I didn't measure it too closely. But what is interesting is that if I dial back the cookie setting to only “required cookies” the site tells me it has a lot of work to do in order to dial back “the full power of Forbes.com”.



So I have incurred a huge performance penalty for exercising my rights.

This did provoke a torrent of activity in the browser – over a thousand requests – which included a few 404s and several 302's sending my browser back around the internet. I've not looked at all of them, but the 200 responses all contained “no data”, and none of the sites I saw had appeared when I first loaded the page.

This is appears to be a very elaborate piece of theatre.

It took around 60 seconds to reach the 100% point – while helpfully giving me the option to change my mind at any point.

Another interesting feature of the performance was that the counter slowed down as it progressed! If you've read up on progress bars, you'll know that is exactly the opposite of what you should do if you want to convey an impression of speed.

Finally, changing my browser config to send a “Do Not Track” header had no impact at all on the behaviour. Although at the time of writing, this is still a proposal for HTTP.

Usually I don't wear my tin foil hat when browsing the internet – I'm OK that websites need a way to fund the content they publish but I am very disturbed that sites seem to go to such lengths to try to manipulate their users' behaviour.

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