## 4 Results: Analysis of the Integration of VR, AR, and MR in the Design Process
### Aggregated Results by Usability Dimension: Effectiveness, Efficiency, and Satisfaction  
Figure 10 summarises the results obtained for the three dimensions of usability--effectiveness, efficiency, and satisfaction--in the different Design Units. A positive devel  
Figure 9: Design variants generated with Gravity Sketch: (**a**) the ideation process for the design of the reading armchair (freehand sketching included within the immersive environment) and (**b**) definition of the selected solution; (**c**) the ideation process for the high stool (freehand sketching included within the immersive environment) and (**d**) a presentation of colour and backrest variations. opment is observed, directly proportional to the accumulated experience of the designer within the immersive environment. The dimension 'Effectiveness' shows the degree to which users can complete tasks with accuracy and completeness in relation to the established goals. The results indicate a positive development throughout the Design Units, from a value of 1.55 in Design Unit 1 (ring) to 2.85 in Design Unit 7 (high stool). This increase reflects an improvement in the ability to achieve design purposes, mainly from Design Unit 5 onwards, where the consolidation of the learning curve and effective adaptation to the immersive environment are observed. However, Design Units 3, 4, and 5 present lower effectiveness values (1.25, 1.20 and 1.40) compared to Design Unit 2 (1.60). This discontinuity could be due to the increase in the geometric complexity of the models developed (vehicle, mouse, and outdoor armchair), or also to an intermediate learning stage, where the designer had not reached sufficient mastery of the immersive environment to face more demanding tasks. In these Design Units, effectiveness was also the dimension with the lowest score compared to efficiency and satisfaction. Only in Design Unit 2 (candle holder) was it the highest rated, while in Design Units 4, 5, and 6 it obtained lower results. These observations indicate that effectiveness is the dimension that requires the highest level of experience to be achieved in immersive environments, being more sensitive to task difficulty and to the familiarity of the user with the software and hardware platform. The dimension 'Efficiency' analyses the resources used (time, physical effort, cognitive effort, and actions required to complete a task) in relation to the accuracy and completeness with which users achieve their goals. The results reflect a general positive progress throughout the study, especially from Design Unit 5 onwards. The earlier Design Units show lower and similar values, reaching higher levels in the latter ones (1.85 in Design Unit 6 and 2.45 in Design Unit 7). This suggests a gradual improvement in operational performance related to greater familiarity with immersive technologies, which encouraged a reduction in task interruptions and better management of errors during the design process. Although the time to complete task indicator worsened in Design Units 6 and 7, this result was offset by improvements in other aspects (human error, interactivity, and learning curve), consolidating sustained overall efficiency. It is worth noting that in two intermediate Design Units (1 and 3), efficiency exceeded effectiveness and satisfaction, suggesting that this result can be achieved even before full mastery of the immersive environment. Overall, the results  
Figure 10: Usability dimension analysis in the Design Units. show that efficiency is sensitive to the balance between user experience, design complexity, and interface ergonomics. The 'Satisfaction' dimension assesses the extent to which users perceive their immersive experience as positive, comfortable, and acceptable in relation to their expectations and needs. The results indicate a gradual growth. However, it is worth noting that good results appear in the first two Design Units, possibly due to the initial satisfaction obtained from discovering this type of environment.