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Direct perception, as part of the ecological approach to perception, defines a relationship between an organism and their environment that is specified by lawful information. Researchers can apply the ecological approach to eXtended Reality (XR) work to obtain a richer understanding of users’ perception-action coordination in novel virtual settings. To encourage widespread adoption of this theoretical framework, this methodological paper introduces four major concepts from the ecological approach that are highly relevant to XR applications. We also provide an overview of existing literature to illustrate how those concepts may be used to inform and test their designs. These elements include the study of calibration and attunement, affordances, action based responses, and intrinsic scaling for measurements. The goal of this work is to increase awareness of the value of the ecological approach, and to provide a practical, evidence-based reference for researchers interested in applying these techniques in XR research. 

This empirical evaluation aimed to investigate how size perception differs between OST AR and the real world, focusing on two judgment methods: verbal reports and physical judgments. Using a within-subjects experimental design, participants viewed target objects in different sizes in both AR and real-world conditions and estimated their sizes using verbal and physical judgment methods across multiple trials. The study addressed two key hypotheses: (H1) that size perception in AR would differ from the Real World, potentially due to rendering limitations in OST-HMDs, and (H2) that verbal reports and physical judgments would yield different levels of accuracy due to distinct cognitive and perceptual processes involved in each method. Our findings supported these hypotheses, revealing key differences in size perception between the two judgment methods and viewing conditions. Participants consistently underestimated object sizes when using verbal reports in both AR and real-world conditions, with more pronounced errors in AR. In contrast, physical judgments yielded more accurate size estimates under both viewing conditions. Notably, the accuracy of verbal reports decreased as target sizes increased, a trend that was particularly evident in AR. These results underscore the perceptual challenges associated with verbal size judgments in AR and their potential limitations in applications requiring precise size estimations. By highlighting the differences in accuracy and consistency between verbal and physical judgment methods, this study contributes to a deeper understanding of size perception in OST AR and real-world contexts. 

Many AR applications require users to perceive, estimate and calibrate to the size of objects presented in the scene. Distortions in size perception in AR could potentially influence the effectiveness of skills transferred from the AR to the real world. We investigated the after-effects or carry-over effects of calibration of size perception in AR to the real world (RW), by providing feedback and an opportunity for participants to correct their judgments in AR. In an empirical evaluation, we employed a three-phase experiment design. In the pretest phase, participants made size estimations to target objects concurrently using both verbal reports and physical judgment in RW as a baseline. Then, they estimated the size of targets, and then were provided with feedback and subsequently corrected their judgments in a calibration phase. Followed by which, participants made size estimates to target objects in the real world. Our findings revealed that the carryover effects of calibration successfully transferred from AR to RW in both verbal reports and physical judgment methods. 

Research has shown that environmental cues affect long-term memory and spatial cognition, but there is still a lack of understanding of the exact characteristics that produce these effects. We conducted a virtual reality (VR) within-subjects repeated measures study on 51 participants to test color congruency. Participants saw and studied 20 objects, then completed object recall and placement tasks in a recall room with a congruent or incongruent color. The objective and subjective data we gathered suggest that congruent color conditions influenced long-term memory and speed for recalled objects. Object size was also shown to influence spatial cognition and long-term memory. 

Mixed reality (MR) interactions feature users interacting with a combination of virtual and physical components. Inspired by research investigating aspects associated with near-field interactions in augmented and virtual reality (AR & VR), we investigated how avatarization, the physicality of the interacting components, and the interaction technique used to manipulate a virtual object affected performance and perceptions of user experience in a mixed reality fundamentals of laparoscopic peg-transfer task wherein users had to transfer a virtual ring from one peg to another for a number of trials. We employed a 3 (Physicality of pegs) X 3 (Augmented Avatar Representation) X 2 (Interaction Technique) multi-factorial design, manipulating the physicality of the pegs as a between-subjects factor, the type of augmented self-avatar representation, and the type of interaction technique used for object-manipulation as within-subjects factors. Results indicated that users were significantly more accurate when the pegs were virtual rather than physical because of the increased salience of the task-relevant visual information. From an avatar perspective, providing users with a reach envelope-extending representation, though useful, was found to worsen performance, while co-located avatarization significantly improved performance. Choosing an interaction technique to manipulate objects depends on whether accuracy or efficiency is a priority. Finally, the relationship between the avatar representation and interaction technique dictates just how usable mixed reality interactions are deemed to be. 

As virtual reality (VR) technology sees more use in various fields, there is a greater need to understand how to effectively design dynamic virtual environments. As of now, there is still uncertainty in how well users of a VR system are capable of tracking moving targets in a virtual space. In this work, we examined the influence of sensory modality and visual feedback on the accuracy of head-gaze moving target tracking. To this end, a between subjects study was conducted wherein participants would receive targets that were visual, auditory, or audiovisual. Each participant performed two blocks of experimental trials, with a calibration block in between. Results indicate that audiovisual targets promoted greater improvement in tracking performance over single-modality targets, and that audio-only targets are more difficult to track than those of other modalities.