I came across a dissertation in political science that contained a nice description of the concept:
The basic idea of the learned helplessness theory is that noncontingency leads to performance deficits. Individuals exposed to uncontrollable events learn that events are independent of their own behaviour, and it has a debilitating effect on their future performance. Development of an expectation of future uncontrollability results in a reduction of the incentive for coping (Overmier, 2002).
“Helplessness is present when a group or person or animal displays inappropriate passivity; failing through lack of mental or behavioural action to meet the demands of a situation in which effective coping is possible” (Peterson et al., 1995, 229).
Source: Inta Mierina