arousal among other states and is easy
to use unobtrusively, it is suited for
changes in the order of minutes, not for
time-sensitive events in seconds and
milliseconds. EEG, on the other hand,
increasingly provided in commercial
devices, is better suited for time-precise
measurements. For example, the study
of how emotional expressions modulate
the processing of touch can be done by
event-related potential (ERP) in EEG
resulting from touch. Studies show
that the use of EEG is compatible with
commonly available HMDs.
Eye tracking, which recently
appeared commercially to be used
inside HMDs, can be used both to
identify whether users attend to
a particular stimulus to track its
emotional response, and to track
psychophysiological phenomena such
as cognitive load and arousal. As an
example, the setup in Figure 1 includes
VR, haptics, and physiological sensors.
Figure 2. Rela World using VR and physiological sensors (EEG) for a neuroadaptive meditation environment [ 6].
Figure 1. Bringing it all together: hand tracking of the user through a glass. Wearable haptics, an EEG cap, and an HMD for VR allow the simulation
of a situation in which a person sitting in front of the user touches her hand with different facial expressions [ 1, 2, 4].