## 2 Literature Review
### Conceptual Framework  
The model adopted in this study is inspired by the Stingray model, a conceptual framework proposed by the Board of Innovation [50]. This model is an evolution of the widely recognized Double Diamond Model, which was originally developed by the UK Design Council to represent the process of design thinking through four stages: Discover, Define, Develop, and Deliver. The Double Diamond emphasizes divergent and convergent thinking, encouraging designers to first explore the problem space broadly before narrowing down to specific solutions. However, it has been criticized for being time-consuming and susceptible to cognitive biases during decision-making [51].  
In response to these limitations, the Board of Innovation proposed the Stingray model, which reconfigures the design process to address the challenges of speed, objectivity, and complexity--especially relevant in an era dominated by generative AI. Although the Stingray model has not been extensively discussed in academic literature (Figure 1), it introduces a tri-phasic structure--Training; Development; and Iteration--that mirrors the learning and refinement processes found in AI systems. The \"Training\" phase involves collecting data and identifying core insights, the \"Development\" phase focuses on generating and selecting ideas, and the \"Iteration\" phase emphasizes rapid testing and refinement [52; 53].  
This study refines and extends the Stingray model, proposing a modified framework tailored specifically for packaging design in the context of generative AI. The model is adopted here because packaging design increasingly demands adaptive creativity, accelerated iteration, and data-informed decision-making--all of which align with the strengths of the Stingray approach. By integrating AI capabilities, the improved model aims to facilitate faster identification of design problems and more efficient generation of optimized solutions while minimizing human bias and cognitive load.  
The new Stingray model, which integrates perceptual engineering, AHP hierarchical analysis, and generative tools, is not only a way of thinking but also a set of design processes (Figure 2). The innovation lies in the inclusion of perceptual engineering in the \"training\" phase, which transforms users' perceptual preferences into executable design  
Figure 1: Original Stingray model.  
parameters and measures the perceptual evaluation of the packaging through questionnaire collection, clarifying the direction of improvement and thus guiding the design of packaging designs that are more in line with users' psychological needs and preferences [54]. In the \"development\" phase, AHP hierarchical analysis was used to rank the perceptual vocabulary collected in the previous phase and to judge the importance of each indicator based on the scores provided by experts [55]. In the \"iterative\" stage, ChatGPT (GPT-4, OpenAI) and Midjourney (V5.2) were used to input the design instructions for the AI-generative design. Artificial Intelligence enhances the iterative potential of the product at a later stage, and it is possible to change the design instructions to satisfy the customer's needs at different stages of the process, which is much more cost-effective and time-saving than traditional design methods [56].