CONCEPT
Tight Coupling
Perrow's term for systems in which processes are time-dependent, invariant in sequence, and admit no slack — so that when disruption occurs, it propagates at the speed of the process itself, outrunning the cognition required to intervene.
Tight coupling is the second structural condition Perrow identified for normal accidents. In a tightly coupled system, process A must complete before B can begin; there is no buffer time, no spare capacity, no room for improvisation. Operators must act immediately, under time pressure, with incomplete information, in conditions that make intervention more likely to worsen than to correct the situation. Loose coupling, by contrast, absorbs disruption through buffer inventories, redundant pathways, flexible sequences, and organizational slack. The coupling determines whether operators have the time and space to intervene effectively or whether events outrun their capacity to understand what is happening. Coupling is the second axis of Perrow's matrix; when combined with interactive complexity, it makes normal accidents statistically inevitable.
In The You On AI Field Guide
Coupling is the temporal dimension of system architecture, complementing the structural dimension captured by interactive complexity. A system can be complex but loosely