A memorial, called the “Outdoor Symbolic Memorial” was built on the site. Several monuments make up the memorial: the Gates of Time, which depicts “the innocence of the city before the attack… and the hope that came from the horror in the moments and days following the attack”; the Field of Empty chairs, which lies on the footprint of the building, and is made up of 168 chairs to represent each of the victims; the Survivor tree, a tree which bore the full brunt of the attack and remained standing, transforming it into “a living symbol of resilience.” Despite McVeigh's intentions to make the Alfred P. Murrah building a visual depiction of the destruction of government, it, along with the public's response to the bombing, has been transformed by the public into a symbol of recovery and healing. Though terrorism seeks to create symbols, their meaning may be changed by similarly symbolic rhetoric created by the victims of the original attack. The psychology of symbols Psychology discusses the effect of symbols on the human mind, and gives insight into why the rhetoric of terrorism may be conducted partly through symbols. An overview of the psychology of symbols is relevant to terrorism because it is in the mind that symbols find validation and reality, allowing terrorist attacks create an effect on a wide audience. The influence of images on humans has long been studied by art historians. David Freedberg, argues that humans react to images not simply on a cognitive level, but on an emotional one. Additionally, the psychology of persuasion has noted that if people see a symbol of authority, even if they know the groups or person projecting the symbol has no actual authority, they begin to believe that there is real authority in that party. Both of these theories contribute to arguments scholars make about the role of psychology in terrorism by helping to explain why humans react to terrorist attacks. Psychology also contributes to the understanding of how visual propaganda put forward by terrorist groups contributes to their organization. In the book, “Psychology of Terrorism,” author Randy Borum argues that projecting an image of solidarity and power makes terrorist groups more attractive as social collectives, even if the person joining the group does not at the outset believe in its ideology. A sense of belonging is one of the primary motivating factors for people joining terrorist groups.