The goal of this research is to understand how people perceive growing building fires. Fires can quickly transition from an ember to a blaze and threaten the safety of people nearby. Fire safety science has found that predicting how occupants respond during fires can improve building designs and safety systems. Identifying whether a real threat is present is a crucial step in building occupants taking action during a fire. Past studies observed that initial signs of a fire tend to be ambiguous, with occupants often investigating the source. When a fire is present, fire cues can be visible to the occupant, which include smoke and, depending on proximity, flames. This research examines whether individuals detect changes in smoke or flames and use them to judge the risk of the fire. Better understanding how people use visible fire cues to guide decision making during fire emergencies can improve life safety system design in buildings.<br/><br/><br/>This research investigates how well humans can perceive changes in visible fire cues and link these cues to the risk posed by the developing fire. Previous research has observed that individuals can detect changes in visible fire cues. Whether individuals use the rate of change in fire cues to judge posed risk is unknown. Using decision-making tasks, human participants make judgments about software-simulated building fires. By varying characteristics of the fires and buildings, this research investigates how well people can detect changes in fires and use this information to judge posed risk. Investigating this connection can inform the extent to which dynamic changes in fire cues are used by occupants to assess the posed risk of a fire and influence pre-movement decision making, which can be incorporated into theoretical models of occupant behavior.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.