"Anomalous" Kovacs humps have been reported in athermal systems, i.e. Δ Δ P ≤ ≤ 0 , i.e. a minimum is observed instead of a maximum. Although the linear response connection between the Kovacs hump and the direct relaxation function can be extended to athermal systems, not all the modes are positive definite—the standard version of the fluctuation-dissipation theorem does not apply. This is the key that facilitates the emergence of anomalous behavior.