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abstract: Perceived heaviness of lifted objects has been shown to scale to a ratio of muscle activity and movement during elbow lifts. This scaling reflects the importance of the forces applied to an object and the resulting kinematics for this perception. The current study determined whether these perceived heaviness dynamics are similar in other lifting conditions. Anatomically sourced context-conditioned variability has implications for motor control. The current study investigated whether these implications also hold for heaviness perception. In two experiments participants lifted objects with knee extension lifts and with several arm lifts and reported perceived heaviness. The resulting psychophysiological functions revealed the hypothesized muscle activity and movement ratio in both leg and arms lifts. Further, principal component regressions showed that the forearm flexors and corresponding joint angular accelerations were most relevant for perceived heaviness during arm lifts. Perceived heaviness dynamics are similar in the arms and legs. / Dissertation/Thesis / Masters Thesis Psychology 2016

This exploratory study investigated how perception of heaviness and presence in the virtual reality experience is affected by limitations in the velocity with which a virtual object is lifted. An interaction method aiming to urge the user to lift certain objects at a certain velocity was designed, developed and evaluated in an iterative manner. Two cycles of user tests were conducted to explore and refine the interaction method. Subsequently, based upon the proposed interaction method, a room scale virtual reality puzzle game was developed and evaluated with a between-subject user test. Results indicated that the proposed interaction method bear potential to give users a notion regarding the heaviness of virtual objects, without affecting the presence of the VR experience. However, the results did not show clear signs in regard to limiting the participants' lift velocity. Ultimately, the interaction method needs further research. / Denna undersökande studie studerade hur uppfattningen av tyngd och sinnesnärvaro i den virtuella verkligheten påverkas av begränsningar i hastigheten med vilken ett virtuellt objekt lyfts. En interaktionsmetod som syftade till att uppmana användaren att lyfta vissa objekt med en viss hastighet utformades, utvecklades och utvärderades på ett iterativt sätt. Två cykler av användartester genomfördes för att utforska och förfina interaktionsmetoden. Därefter, baserat på den föreslagna interaktionsmetoden, utvecklades och utvärderades ett virtuellt verklighetspusselspel med ett användartest. Resultaten indikerade att den föreslagna interaktionsmetoden har potential att ge användarna en uppfattning om tyngden hos virtuella objekt utan att negativt påverka sinnesnärvaron i VR-upplevelsen. Resultaten visade emellertid inte tydliga tecken när det gäller att begränsa deltagarnas lyfthastighet. I slutändan behöver interaktionsmetoden ytterligare forskning.