Social information is particularly prominent in digital settings where the
design of platforms can more easily give real-time information about the
behaviour of peers and reference groups and thereby stimulate political
activity. Changes to these platforms can generate natural experiments allowing
an assessment of the impact of changes in social information and design on
participation. This paper investigates the impact of the introduction of
trending information on the homepage of the UK government petitions platform.
Using interrupted time series and a regression discontinuity design, we find
that the introduction of the trending feature had no statistically significant
effect on the overall number of signatures per day, but that the distribution
of signatures across petitions changes: the most popular petitions gain even
more signatures at the expense of those with less signatories. We find
significant differences between petitions trending at different ranks, even
after controlling for each petition's individual growth prior to trending. The
findings suggest a non-negligible group of individuals visit the homepage of
the site looking for petitions to sign and therefore see the list of trending
petitions, and a significant proportion of this group responds to the social
information that it provides. These findings contribute to our understanding of
how social information, and the form in which it is presented, affects
individual political behaviour in digital settings.Comment: Prepared for delivery at the 2014 Annual Meeting of the American
Political Science Association, August 28-31, 201