“…Besides, psychological and sociological variables can be observed on side of paths, such as heart rate, skin conductance, emotional and aesthetic evaluations of specific artworks [29,47,48], interactions with groupmates, degree of attention, boredom or fatigue. Automatic systems could be complemented with manual activities, like paper-and-pencil annotations and questionnaires [28,34,47]. From questionnaires one can estimate demographic related and museum visit related features [34] like age, gender, educational level, number of visits per year to museums, etc.…”