  In the last decades an increasing deal of research has investigated the
phenomenon of opinion misperception in human communities and, more recently, in
social media. Opinion misperception is the wrong evaluation by community's
members of the real distribution of opinions or beliefs about a given topic. In
this work we explore the mechanisms giving rise to opinion misperception in
social media groups, which are larger than physical ones and have peculiar
topological features. By means of numerical simulations, we suggest that the
structure of connections of such communities plays indeed a role in distorting
the perception of the agents about others' beliefs, but it is essentially an
indirect effect. Moreover, we show that the main ingredient that generates the
misperception is a spiral of silence induced by few, well connected and
charismatic agents, which rapidly drives the majority of individuals to stay
silent without disclosing their true belief, leading minoritarian opinions to
appear more widespread throughout the community.
