Signage systems are visual information systems that indicate the direction, allow for identification, and show safety information and regulations to occupants via graphics or text during emergencies. Wayfinding is difficult in large and complex buildings, such as large shopping malls. Occupants can be disoriented while searching for their way in such buildings. This problem can be more serious in emergency situations, such as fires, than in normal situations. Signage systems can be helpful in solving this problem. Domestic and overseas standards on emergency signage systems specify that the signage should be noticeable, easy to read, and easy to understand. However, most regulations do not quantify the effectiveness of such signage systems under emergency situations. To address these issues, in this study, several experiments were conducted considering the viewing distance and angle using a backlit signage system, and changes in cognition under smoke conditions were analyzed. First, the concept of effective cognition area (ECA) was introduced to analyze the relationship between the viewing distance and angle. Experiments were conducted using a backlit emergency exit sign, and the changes in the ECA in a smoke situation were analyzed. Finally, the results of this study were compared with those of previous studies. Furthermore, the extent to which occupants can recognize the signage system was quantified. If the concept of ECA developed in this study is applied to the development of emergency signage design, more diverse evacuation scenarios could be designed.