Lord's invocation of an era of confidence and certainty was also a relevant theme at the height of the Cold War.[12] The University of California sociologist Fred Davis comments that nostalgia "thrives ... on the rude transitions wrought by such phenomena as war, depression, civil disturbance, and cataclysmic natural disasters – in short, those events that cause masses of people to feel uneasy and to wonder whether the world and their being are quite what they always took them to be."[13] The turmoil and uncertainty of the early Atomic Age and the onset of profound social changes made the old concepts of the nuclear family and traditional gender roles, reflected in the behaviour of Titanic's passengers, resonate with a mid-1950s audience.[14]