muCap: Connecting FaceReader to z-Tree

μCap (muCap) is a software package (citeware) for economic
experiments enabling experimenters to analyze emotional states of
subjects using z-Tree and FaceReader. μCap is able to create videos
of subjects on client computers based on stimuli shown on screen
and restrict recording material to relevant time frames. Another
feature of μCap is the creation of time stamps in csv format at
prespecified screens (or at prespecified points in time) during the
experiment, measured on the client computer. The software makes it
possible to import these markers into FaceReader easily. Until
recently, connecting z-Tree and FaceReader was only possible using
workarounds or by undertaking many successive actions manually.
μCap is the first program that significantly simplifies this
process with the additional benefit of extremely high precision.
This paper describes the usage, underlying principles as well as
advantages and limitations of μCap. Furthermore, we give a brief
outlook of how μCap can be beneficial in other contexts.