The effect of confinement on stochastic resonance in continuous bistable   systems
  Using the input energy per cycle as a quantifier of stochastic resonance (SR), we show that SR is observed in superharmonic (hard) potentials. However, it is not observed in subharmonic (soft) potentials, even though the potential is bistable. These results are consistent with recent observations based on amplitude of average position as a quantifier. In both soft and hard potentials, we observe resonance phenomenon as a function of the driving frequency. The nature of probability distributions of average work are qualitatively different for soft and hard potentials. 
Shubhashis Rana, Sourabh Lahiri and A. M. Jayannavar
cond-mat.stat-mech