Vibration serviceability of structures for human occupancy has become an important part of the design of slender civil engineering structures such as footbridges. In the past decades, a considerable amount of research has been carried out within the field and international codes of practice and state-of-the-art design guidelines been improved considerably. However, there are several important questions that remain unanswered. In particular the response of pedestrians to footbridge vibrations is severely under-researched. This is primarily due to lack of data from real-life footbridges subject to in-service traffic. In addition, the lack of a generally accepted way to quantify measured vibration response on footbridges makes it difficult to interpret data from already published experiments. In this paper, various methods to quantify human-response to vibrations are reviewed and put in relation to the results obtained from a controlled crowd test on a steel footbridge in Reykjavik, Iceland. A systematic quantification of the measured vibration response is carried out and the results are presented statistically through their probability distributions. Finally, testimonies from participants in a controlled perception tests are used in conjunction with measured responses, to obtain valuable information about human response to footbridge vibration. It is shown that there is only a small correlation between the subjective rating and the vibration felt by the pedestrians.