This paper explores the effects of magnitude and phase cues on human motor adaptation. Participants were asked to excite virtual second-order systems at their resonance frequencies via a two-degree of freedom haptic interface, with visual and visual plus haptic feedback conditions. Their motor adaptations were studied through catch trials. The results indicate that, i) humans adapt to a nominal virtual system resonant frequency, ii) humans shift to higher and lower natural frequencies during catch trials regardless of feedback modality and force cues, iii) humans can detect changes in natural frequency when gain, magnitude, and phase cues are manipulated independently, and iv) humans are able to detect changes in natural frequency when the feedback (visual or visual plus haptic) is delayed such that the phase shift between the nominal system and catch trial system is zero.