Mechanistic complexity is fundamental: Evidence from judgments, attention, and memory

What makes an object complex? Complexity comes in many different forms. Some objects are visually complex but mechanistically simple (e.g., a hairbrush). Other objects are the opposite; they look simple but work in a complex way (e.g., an iPhone). Is one kind of complexity more fundamental to how we represent, attend to, and remember objects? Although most existing psychological research on complexity focuses on visual complexity, we argue that mechanistic complexity may be more consequential: Across five preregistered experiments (N = 780 adults), we show that mechanistic complexity not only predicts explicit judgments but also drives visual attention and memory. Thus, representations of object complexity-and object representations more broadly-rely on more than just external appearance. (PsycInfo Database Record (c) 2025 APA, all rights reserved).