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Stressed out? It might be because your video is buffering

We’ve all experienced poor video playback from time to time. It’s usually frustrating for sure, but do you know it increases your heart rate too? According to a neurological study done by Ericsson, waiting for mobile video to load really stresses people out. The study was part of their Mobility Report Mobile World Conference Edition 2016 released for the conference in February.

User experience objectified

Ericsson contracted out the study to a consultant group that specialised in neuroscience. The idea was they wanted to get hard data on how the mobile experience actually affects people. Surveys can be used to gather people’s reactions to certain situations, but by hooking people up to various measuring devices, they were able to see physiological responses such as brain activity and stress levels. That type of data is completely objective, where surveys are always subjective – from the point of view of the respondent. Two people could have the same exact experience, but answer the survey completely differently.

Don’t get me wrong. Surveys are great tools, but by directly measuring people’s responses to certain circumstances we’re able to see things they might not even be aware of – but their body’s reactions tell the whole story.

In the study, “Brain activity, eye movements, and pulse were recorded while subjects completed various tasks by browsing the web and watching video clips.” They also surveyed the subject’s views of the network and content providers before and after the tests by examining specific brain activity.

The objective results

There were three groups in the study. One was exposed to high degree of delays, the second a medium degree, and third and luckiest had no delays at all.

On average, heart rates increased 38% with mobile content delays. This includes web page loading as well as videos. The subjects were already stressed (13% on average) because they were given a timed task to complete. But their stress levels rose 15% during video re-buffering.


One of the factors measured in this study is cognitive load. I’m not a neurologist, so I’ll quote the report to explain what that is: “Cognitive load is a score that measures the amount of information that a person is processing and ‘holding active’ in the dorsolateral prefrontal cortex (DL-PFC) part of the brain. A high cognitive load is part of a stress response.”

I’m not sure that helped much, but all we really need to know is that if the result is high, then someone is stressed. The study compared the cognitive load of delayed mobile content to other activities to help make it more understandable. They found that the resulting stress is about the same as watching a horror movie, and a little less than solving a maths problem (a hard one I’d assume).


In order to evaluate the subject’s reactions to both networks and content providers, they assigned Net Promoter Scores (NPS) based on the brain activity observed. They then measured the NPS before and after the tests. The subjects that had medium delays had a poorer opinion of the network providers than they did when the test started.

Interestingly though, the subjects that had long delays shared the blame across both the network and the content providers. People expect content providers to deliver optimised content and are willing to give them a benefit of the doubt unless the delays are really long.

All this data gave Ericsson an objective look at how mobile performance impacts people. The data they gathered is pretty convincing that mobile performance is everything. But it isn’t possible to control all aspects of your mobile video viewers experience. A lot has to do with the connection on their end as well as the device. But if you believe the results from this study, you should be doing everything you can do to help avoid delays in video playback or buffering. The better the playback, the higher the engagement and opinions of the viewers. And isn’t that what you want?

What do you think of the study? Is it enough to motivate you to re-examine the performance of your mobile sites and videos?

Oliver Burt

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