 investigating upper limb perceptual asymmetries for unconstrained active exploration of stiffness use. This presentation is an extension to our work investigating the effects of exploration strategies on human haptic perception. We believe this investigation is important as the internal psychophysics of the human operator are often unaccounted for in modern teleoperator usage. Our study is motivated by the work of Square et al. who found that the left hand was perceptually superior in curvature discrimination than the right hand for a right hand dominant participant pool. While many studies have shown similar results for other proprioceptive and cutaneous cues, it is unknown whether this is also true for kinesthetic use. In this manuscript, we investigate this question. Do perceptual asymmetries exist for active exploration of kinesthetic use? We performed a psychophysical assessment of stiffness perception by obtaining the just noticeable difference for stiffness discrimination in virtual torsion springs for both the hands. We used a custom single degree of freedom direct drive rotary haptic feedback device that uses a Maxon RE-50 motor to provide the haptic feedback and a 500 counts per turn encoder to monitor the angular displacement. The participants can feel the virtual torsion springs by pronating and supinating their wrist. A consulate simulink interface is used to drive the motor to generate the virtual linear torsion springs where the torque linearly increases with the input angular displacement. The simulink interface allows for a quick change in spring stiffness as shown in the figure where the output torques are different even though the input angular displacements are the same. We used two of these devices, one for each hand. We used a two alternate, two interval force choice method of constant simile paradigm for 14 right hand dominant participants in subject design. We used one reference spring and five comparison springs. Five catch trials were also used to check for response bias. Psychometric curves were plotted for all participants and the GND was set at a proportion correct percentage of 75%. We found that the participants demonstrated significantly lower GNDs when exploring with their left hand. To summarize, we performed a psychophysical assessment of whether stiffness perception is affected by the choice of hand used to explore torsion springs. In a right hand dominant participant pool, we found that the participants were able to better discriminate between stiffness cues using their left hand. We believe that these results may be of significant importance to the robotics and psychophysics communities who may design control strategies or experiments that sometimes assume the two hands to be perceptually equal. Thank you for your time. You can find our contact information and supplemental information on our lab website linked in the QR code.