## 5 Conclusions  
In summary, this study experimentally investigated how the complexity and display quantity of 3D virtual objects affects the VWM capacity in AR interfaces for mobile phones. After eliminating the interference factors of familiarity, concreteness and similarity in 3D virtual material objects through a 5-point Likert scale rating, we further conducted a formal mobile phone-based AR experiment and successfully manipulated the complexity and the set size of 3D virtual objects. A change detection paradigm was deployed on a smartphone program developed by Unity 3D. Three parameters were measured and analyzed in the formal experiment: reaction time, proportion correct and VWM capacity (Cowan's K). The formal experimental results revealed that the user's behaviour on MAR interfaces was influenced by the complexity and quantity of the 3D virtual objects displayed. Here, we demonstrate for the first time that there is a correlation between the complexity of 3D virtual objects and VWM capacity in MAR interactions. Specifically, the VWM capacity in MAR interfaces was not fixed and can be reduced by highly complex 3D virtual objects. Our results are largely consistent with the resource-based theories and proved that the memory resources are flexibly allocated according to the complexity of each virtual AR target. Once the complexity of the 3D virtual objects increases, the amount of VWM resources allocated to each item decreases. These findings enhance our understanding of how complexity and quantity in MAR interfaces affect VWM performance. Thus, while designing the MAR interface, designers should either minimize the complex forms of virtual objects to reducethe memory load, or reduce the total number of 3D virtual objects per interface when there is a need to retain the details of virtual objects. These results can guide the design of the presentation and interaction of virtual information in MAR applications, especially the multi-object interactive AR games on mobile devices. Conceptualization, X.D. ; Methodology, J.Z. ; Validation, S.J. and N.Z., Formal analysis, J.Z. ; Resources, S.J. and N.Z. ; Data curation, X.D., J.Z. and S.J. ; Writing--original draft preparation, X.D., J.Z. and S.J. ; Writing--review and editing, J.Z., S.J., W.X. and N.Z. ; Supervision, J.Z. and W.X. All authors have read and agreed to the published version of the manuscript. This paper was supported by the National Natural Science Foundation of China (No. 72201128), the China Postdoctoral Science Foundation (No. 2023M730483) and the Collaborative Education Program of the Chinese Education Ministry (No. 202102298009). After consideration by the Institutional Review Board of this institution, the experimental design and protocol of the study were found to be scientifically sound, fair and impartial, and did not cause harm or risk to the subjects. The recruitment of subjects was found to be based on the principle of voluntary and informed consent and protection of the rights and interests of the participants as well as their privacy, and the content of the study was found to be free from conflicts of interest as well as violation of moral and ethical principles and legal prohibitions. It also complied with the ethical standards set forth in the Declaration of Helsinki. The Institutional Review Board agreed that the work on this project was proceeding as planned (approval date: 10 January 2023). Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. Data Availability Statement: Data is contained within the article. We would like to thank all authors for their contributions to this paper, all participants for taking the time to patiently complete the experimental content, and the College of Furnishings and Industrial Design for providing the experimental site. We are additionally thankful to [PERSON] and [PERSON] for their advice concerning project administration on the manuscript. Author [PERSON] was employed by the company Dehua TB New Decoration Material Co., Ltd.