This research investigates the ability of subjects to detect small haptic effects and the associated gains in task performance with various configurations of haptic stimuli. Variations in force amplitude, shape, and pulse duration used to create the effects are studied. An adaptive-threshold method is used to obtain subjects' detection thresholds for actively explored haptic icons ranging in size from 3 to 5 mm. Detection thresholds are compared for smooth versus rough actively-explored icons. Subjects' detection thresholds for “static icons” (force pulses of 50 to 150 ms duration) are also measured. Results indicate that rough (sawtooth) haptic icons are more easily detected by a human subject than smooth (sinusoidal) icons of the same size. Transient vibrotactile cues may contribute to these observations. Mean subject performance, as measured by Fitts' information-processing rate and by clicks per minute, is shown to improve with the amplitude of haptic stimulus.