Observer-Based Spotting
As the name implies, observer-based spotting relies on the keen eye sight of individuals trained to spot and distinguish between debris, wildlife, and vegetation. This form of monitoring is typically carried out from marine platforms (such as ferries) or manned aircraft. A standard observer-based survey is conducted with a team of two observers and a recorder. By conducting the survey in a team, the observers are able to focus the entirety of their attention on their assigned sections/sides of the path and simply relay the information they see to the recorder who can make note of the categories and locations of spotted objects (15).
The Human Eye
As light enters the human eye, it is converted into electrical signals that our brains receive and translate. This is what allows us to distinguish and identify the objects we see (19).
Training
Professional observers must be able to not only spot and categorize plastic litter from a great distance, but to do so quickly and accurately. In order to hone this skill they have to train their eyes and practice acting as an observer. However, this introduces the possibility of producing data heavily influenced by their amount of training and experience level in the field (15).
