People think, feel, and behave within the confines of what they can conceive. Outside that conceptual landscape, people exhibit hypocognition (i.e., lacking cognitive or linguistic representations of concepts to describe ideas or explicate experiences). We review research on the implications of hypocognition for cognition and behavior. Drawing on the expertise and cross-cultural literatures, we describe how hypocognition impoverishes one’s mental world, leaving cognitive deficits in recognition, explanation, and memory while fueling social chauvinism and conflict in political and cultural spheres. Despite its pervasive consequences, people cannot be expected to identify when they are in a hypocognitive state, mistaking what they conceive for the totality of all that there is. To the extent that their channel of knowledge becomes too narrow, people risk submitting to hypocognition’s counterpart, hypercognition (i.e., the mistaken overapplication of other available conceptual notions to issues outside their actual relevance).