While human brains are specialized for complex and variable real world tasks,
most neuroscience studies reduce environmental complexity, which limits the
range of behaviours that can be explored. Motivated to overcome this
limitation, we conducted a large-scale experiment with electroencephalography
(EEG) based brain-computer interface (BCI) technology as part of an immersive
multi-media science-art installation. Data from 523 participants were
collected in a single night. The exploratory experiment was designed as a
collective computer game where players manipulated mental states of relaxation
and concentration with neurofeedback targeting modulation of relative spectral
power in alpha and beta frequency ranges. Besides validating robust time-of-
night effects, gender differences and distinct spectral power patterns for the
two mental states, our results also show differences in neurofeedback learning
outcome. The unusually large sample size allowed us to detect unprecedented
speed of learning changes in the power spectrum (~ 1 min). Moreover, we found
that participants' baseline brain activity predicted subsequent neurofeedback
beta training, indicating state-dependent learning. Besides revealing these
training effects, which are relevant for BCI applications, our results
validate a novel platform engaging art and science and fostering the
understanding of brains under natural conditions
