  A snap-through bifurcation occurs when a bistable structure loses one of its
stable states and moves rapidly to the remaining state. For example, a buckled
arch with symmetrically clamped ends can snap between an inverted and a natural
state as the ends are released. A standard linear stability analysis suggests
that the arch becomes unstable to asymmetric perturbations. Surprisingly, our
experiments show that this is not always the case: symmetric transitions are
also observed. Using experiments, numerics, and a toy model, we show that the
symmetry of the transition depends on the rate at which the ends are released
with sufficiently fast loading leading to symmetric snap-through. Our toy model
reveals that this behavior is caused by a region of the system's state space in
which any initial asymmetry is amplified. The system may not enter this region
when loaded fast (hence remaining symmetric) but will traverse it for some
interval of time when loaded slowly, causing a transient amplification of
asymmetry. Our toy model suggests that this behavior is not unique to snapping
arches, but rather can be observed in dynamical systems where both a
saddle-node and a pitchfork bifurcation occur in close proximity.
