The highest heart-rate levels were twice as high among those watching live theatre as those in the cinema.
Devlin sees the potential for using such technology one day to shape productions according to what gets heart rates going.
When it comes to emotional impact, watching a live performance is so much more thrilling than a version on screen.
Scientists from University College London (UCL) measured heart rates and sweat glands of audience members as they watched both theatre productions and films.