  In an information-rich world, people's time and attention must be divided
among rapidly changing information sources and the diverse tasks demanded of
them. How people decide which of the many sources, such as scientific articles
or patents, to read and use in their own work affects dissemination of
scholarly knowledge and adoption of innovation. We analyze the choices people
make about what information to propagate on the citation networks of Physical
Review journals, US patents and legal opinions. We observe regularities in
behavior consistent with human bounded rationality: rather than evaluate all
available choices, people rely on simply cognitive heuristics to decide what
information to attend to. We demonstrate that these heuristics bias choices, so
that people preferentially propagate information that is easier to discover,
often because it is newer or more popular. However, we do not find evidence
that popular sources help to amplify the spread of information beyond making it
more salient. Our paper provides novel evidence of the critical role that
bounded rationality plays in the decisions to allocate attention in social
communication.
