Group polarisation is the tendency for individuals to make more extreme decisions when they are in a group than when asked to decide on their own. This may be because of social influences within the group or may be because new arguments are heard that reinforce preconceptions and counter arguments are downplayed due to confirmation bias.
Group polarisation was first termed "risky shift" as groups made riskier decisions than lone individuals. Psychological experiments later showed that individuals in groups tended to become more prejudiced and jury members tended to award greater damages than what they would have decided alone.
While Interactive Democracy could conceivably suffer from some group polarisation, it may be less effected than party politics as it involves more individuals without affiliations to pre-existant groups.
While ePetition suggestions may be far flung, the tendency towards extremism can be thwarted by a limited referendum choice, carefully considered by Parliament.