## 3 Methods
### The Rationale for the Selection of the Gesture Types  
In terms of comprehensively exploring the gesture-based interactions within both conventional and immersive environment settings, this study adopted a triadic gesture classification consisting of Surface-Touch gestures, mid-air gestures, and micro finger-touch gestures (Figure 4). The selection of these gesture types was grounded in a synthesis of prior empirical studies and cognitive ergonomics, ensuring that each modality addressed a unique facet of user input behavior relevant to its interaction context. Figure 3: The detailed experimental procedure for evaluating usability and preference in “Phase 2: User Simulation” of Figure 2.  
Surface-Touch gestures were selected as the baseline gesture modality, inspired by the well-established paradigms for direct manipulation interfaces on physical surfaces, such as trackpad-driven, finger gestural interactions [57]. Derived from the tactile and spatial familiarity of touchpad interactions and body-surface contact modalities [58], this gesture type entails utilizing a resting surface--such as the armrest of a sofa or a tabletop--on which finger-base gestures are performed. Moreover, similar approaches in wrist-mounted and surface-coupled input systems have demonstrated high precision and user satisfaction [59], reinforcing the viability of surface-based input for casual and low-effort interactions. Given these characteristics, this gesture type is particularly well-suited to everyday lean-back scenarios, enabling intuitive control of TV interfaces while seated comfortably on a living room couch. Mid-air gestures were incorporated to examine a more immersive and expressive form of interaction, especially relevant in spatial computing environments where free-hand movements can be fully performed. Regarding this, prior research has emphasized the naturalness and intuitiveness of mid-air gestures for controlling digital content in XR environments [60; 61]. Particularly, gestures such as pointing, swiping, and grabbing in mid-air align well with the interactive affordances of virtual objects [45]. However, in lean-back scenarios like television viewing, these mid-air gestures often suffer from a mismatch between spatial scale and user comfort, as the lack of a tactile experience can lead to decreased precision in navigating the interface and increased fatigue over time [32]. Also, as mentioned above, mid-air gestures can induce physical fatigue--commonly referred to as the \"Gorilla Arm\" effect--which poses usability concerns in constrained or prolonged user scenarios [16]. Micro finger-touch gestures offer alternative usability that retains the benefits of hands-free interactions while substantially reducing physical strain. Unlike arm-to-wrist movements, these micro gestures--comprising side finger taps, presses, and swiping--require only minimal motion and can be executed with the hand resting naturally. These kinds of finger-based micro gestures are particularly advantageous for prolonged interactions [62]. Furthermore, the integration of IMU and capacitive sensors into compact form factors such as smart rings enables real-time tracking of micro finger movements with high accuracy [59; 63]. Moreover, approaches such as the MicroPress and the AuraRing illustrate how micro finger-touch gestures can provide a rich interaction vocabulary while maintaining ergonomic comfort [64; 65]. Consequently, this gestural design shows the possibility for micro touch (press)-based gestures to be a promising modality for seamless, fatigue-reducing interaction methods within both screen-based and spatial computing environments. Figure 4: Typological classification of specific hand gestures based on three main gesture types: Surface-Touch gestures, mid-air gestures, and micro finger-touch gestures. The selection of these three gesture modalities is not only theoretically grounded but also pragmatically motivated by the human-centered, technical, and contextual features of the references above.