How visual complexity and color saturation drive purchase intention for tourism cultural and creative products: a dual-path model of cultural sustainability and environmental friendliness via sensory–semiotic integration

Visual design serves as a key medium for value transmission in tourism cultural and creative products (TCCPs), yet how design elements combine to shape value perception and decisions within cultural-tourism contexts remains unclear. This study introduces a sensory-semiotic integration framework, proposing that congruent design—achieved through alignment between visual complexity and color saturation—guides tourists’ perception of specific sustainability values (cultural or environmental) and thereby drives purchase decisions. Three experiments (including an incentive-compatible behavioral study) show that congruent designs (high-complexity-high-saturation and low-complexity-low-saturation combinations) enhance purchase intention and actual choice more than incongruent designs (high-low, low-high). This effect is jointly mediated through dual pathways by perceived cultural sustainability and perceived environmental sustainability. Further analysis reveals differentiated mediation: the high-high combination operates mainly via perceived cultural sustainability, whereas the low-low combination works primarily through perceived environmental sustainability, with perceived cultural sustainability playing a secondary role. Thus, congruent design can directionally guide tourists toward semiotically oriented value perceptions in context. The findings clarify the value-linking mechanism behind design synergy and provide theoretical grounding and actionable strategies for communicating sustainable value through systematic visual design in TCCPs.