e-Nature Positive Emotions Photography Database (e-NatPOEM): affectively rated nature images promoting positive emotions

Affectively rated image databases have their main application in studies that require inducing distinct stimuli on subjects. Widespread databases are designed to cover a broad range of stimuli, from negative to positive (valence), and relaxed to excited (arousal). The availability of narrow domain databases, designed to cover and thoroughly analyze a few categories of images that induce a particular stimulus, is limited. We present a narrow domain affective database with positive images, named e-Nature Positive Emotions Photography Database (e-NatPOEM), consisting of 433 high-quality images produced by professional and amateur photographers. A total of 739 participants evaluated them using a web-based tool to input valence-arousal values and a single word describing the evoked feeling. Ratings per image ranged from 36 to 108, median: 57; first/third quartiles: 56/59. 84% of the images presented valence > middle of the scale and arousal < middle of the scale. Words describing the images were classified into semantical groups, being predominant: Peace/tranquility (39% of all words), Beauty (23%), and Positive states (15%). e-NatPOEM is free and publicly available, it is a valid resource for affective research, and presents the potential for clinical use to assist positive emotions promotion.