To allow for a more subtle distinction between the schemes we treat shoulder surfing as an attack, which only refers to "look over the shoulder". Resilient-to-Shoulder-Surfing describes the resilience against attacks in which attackers try to track sensitive information of the user without any technical aids (see e.g. Resilient-to-Visual-Recording). The user can take precautionary countermeasures (e.g. take distance from surrounding persons), some precautions are not provided in certain environments (e.g. public areas).