Questions as Units of Cognitive Investment: An Interrogative Investment Hypothesis of Individual Differences

We propose the interrogative investment hypothesis: the basic interrogative forms can serve as units for describing how individuals come to differ in cognitive competence. These forms fall into two levels. Questions of object (what, where, who, when, how many) carve reality into aspects; questions of reason (how, why) relate these aspects and underlie methods of inquiry such as the historical and scientific methods. Gardner's theory of multiple intelligences describes individual differences well but offers no mechanism for how they develop, and it has found little support as a model of separable, brain-based faculties. We reframe its domains as outcomes of investment. A spontaneous preference for one kind of question draws attention and time toward it; because time is scarce, this produces cumulative practice, growing competence and increasing reward, which strengthens the preference in turn. The framework also identifies a temporal capacity absent from Gardner's list, cultivated at the short scale by music and at the long scale by history. The hypothesis draws on the developmental order of children's wh-questions, classical accounts of alternating developmental domains, and investment theories of adult intellect. We propose a simple measure of question preference, derive testable predictions, and discuss limitations.