Sargeant, who is Robert F Hartsook Professor of Fundraising at Indiana University in the US, will present the findings tomorrow at a session called Building Donor Loyalty.
The study, which was conducted by University of Indiana PhD student Jen Shang, was based on a radio phone-in appeal in the US. Volunteer phone operators were given three scripts to test.
The first thanked people for calling and asked how much they would like to pledge. The second thanked callers first and then told them how much a previous donor had pledged. Results showed that if the amount quoted was 90 to 95 per cent of the highest donation from the appeal concerned, it
increased the new donation by more than 10 per cent.
The third script gave the same information as script two, but also mentioned that the previous donor was the same gender as the current caller. This led to an increase of more than 30 per cent.
"The psychology of it is that human beings are social animals and we like to do what we think other people are doing," said Sargeant. "It isn't a conscious decision; it's a natural reaction."
However, the test also revealed that when fundraisers quoted a previous gift that was higher than 95 per cent of the highest donation from that appeal, the gift received from the new caller was substantially reduced.
The experiment was also carried out in a direct mail campaign with similar results. Sargeant said he would expect the same experiment to work for street fundraisers, providing the figure quoted in the script was based on 90 to 95 per cent of the previous largest donations.
Sergeant said he saw no reason why the same principles would not work in the UK and hoped charities would start to experiment. "One of the main missions of philanthropic psychology is that I want people to be thinking about conducting these experiments for themselves," he said. "It's about how our results can be put to good practical use in the sector.