Participants were randomized into either a "loss frame" or "gain frame " question. They were:
In both conditions the participants are facing the same task - you have 2 weeks vacation for sure, now put a value on the 2 negotiable weeks. The only difference is whether it was framed a loss (you have 4, how much do you want for the 2) or a gain (you have 2, how much will you pay for 2 more).
Here are the $ distributions of the two groups. You can see a considerable amount of clustering at $5,000 (the maximum value possible) in the loss frame, indicating those people valued the 2 negotiable weeks very highly.
Lastly, here are the average $ values. Those in the loss frame were willing to pay 1.88 times more - neatly in line with the 2:1 ratio usually observed in loss:gain situations.