What kind of reaction is a "trigger reaction"? Is it a immediate and instant reaction?
The context is added:
The available space is too confined,rendering any such meeting of gazes ‘unbearable’, but somehow the weight of that which haunts the scene makes it all the more so. A trigger reaction to a prevalent sense of both unease and not-quiteknowing- what-to-think which to some extent determines the route you end up taking through the grid, and which is surely replicated over and over.