Agreeing to a small request opens the door to agreeing to a bigger one.
A group of volunteers finishes cleaning up a park quickly and notices two nearby streets that need it too. Almost everyone decides to stay. If someone has already agreed to a small request, they're more likely to agree to a bigger one later, as long as it's in line with what they already agreed to.
A field study measured how different households adopted energy-saving behaviors over several weeks. Only 15% of participants who were asked, from the start, to make the maximum number of possible changes met the goal. But when they were first asked for a few small savings and then bigger ones, compliance rose to 45%. Agreeing to the first steps set the stage for agreeing to the ones that followed.
Once we act a certain way, we tend to stay consistent with that action. Agreeing to a small request predisposes us to agree to later requests that align with it.
Source: Souchet, L. & Girandola, F. (2013). Double Foot-in-the-Door, Social Representations, and Environment: Application for Energy Savings. Journal of Applied Social Psychology, 43(2), 306-315.
Asking for a small piece of information before a big one, or a short commitment before a long one (a free trial before an annual subscription, a small first contribution before a larger one), tends to work better than asking for the full commitment upfront.
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