In order to understand memories from the era of the Great depression or World War I or II, it is important to discuss the nature of trauma and its effect on the formation of memory.
PTSD is a neurological disorder which is brought on by stress. Overactivation in the Amygdala, the area of the brain which is most highly associated with the subjective experience of stress, and which is located closely in physical proximity and linked inexorably to the formation of memory. Overactivation in this region of the brain causes a chain reaction which concludes in recurrent dreams or recollections of the event, feelings that the traumatic event is reoccurring – ‘flashbacks’, and intense psychological stress. Overactivation of these areas of the brain therefore in many ways bind these traumatic memories to those who experience them, and as a result cause a great deal of psychological stress as victims re-live the traumatic events they previously survived, as a result effecting the ability to recall certain events or influencing the brain`s focus on certain events. Thus, when experiencing stressful events such as those associated with the Great Depression or World War I, it is likely that the trauma of these events plays a significant effect on memory, both in it`s ability to be recalled or recorded, as well as its subjective interpretation and resulting willingnness to be called forth.
Carson, Neil R., Physiology of Behaviour (Boston: Pearson, 2013)