Marketers spend valuable hours trying to measure the ROI of their advertising efforts, and one common measure is consumer engagement. New research published in the American Marketing Association’s Journal of Marketing Research used automated facial recognition detection and eye tracking technology to uncover the most engaging and effective formula for online video advertisements.

The research found that the best way to grab consumers’ attention is to start with a surprise, and then follow the surprise with content that elicits happy or joyful reactions.

To further retain consumers’ focus, ads should then follow an alternating pattern of emotional delivery, rather than hit consumers with sustained joyous content. The sequence of highs and lows reduces the likelihood that consumers will click away from the advertisement.

“We found that surprise improved attention concentration more than joy did, and joy improved viewer retention more than surprise did, revealing the dual routes to ad effectiveness that these two related, but distinct, emotions play,” say study authorsThales Teixeira of Harvard University, Michel Wedel of the University of Maryland and Rik Pieters of Tilburg University.

The authors say marketers can use these research findings to help create video ads that get and keep consumers’ attention while conveying the desired message.

The study showed 58 adults a series of 28 online video advertisements from popular consumer packaged goods brands including Budweiser, Nivea, Dell and Tide.

It then measured participants’ eye and facial movements in 250 millisecond intervals to minutely track the type and intensity of their reactions, and also their ad skipping behavior. Further details can be found in the article “Emotion-Induced Engagement in Internet Video Advertisements” in the April issue of the Journal of Marketing Research.