Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The "psychological immune system" is a shorthand term used to encompass a number of biases and cognitive mechanisms that protect the subject from experiencing extreme negative emotions. They achieve this by ignoring, transforming or constructing information, making the existing state of affairs more bearable while decreasing the appeal of the alternatives. They operate largely or entirely outside conscious awareness. Psychologists Daniel Gilbert and Timothy D. Wilson coined the term, using the biological immune system as a metaphor for these processes.