TOT states have a subjective phenomenology to them that is worthy of investigation in and of itself. Although examining the mechanisms of word-retrieval failure is an important part of fully understanding TOT experiences, the mechanisms of word-retrieval failure are not the complete picture. For one thing, not all instances of word-retrieval failure result in a TOT state. For another, TOT states are an inherently subjective phenomenon with a potentially unique set of phenomenological qualities that distinguish them from other metacognitive states of awareness and experiences. Understanding the subjective phenomenology of TOTs could help to elucidate important facets of metacognition as well as human consciousness more broadly.

Recent advancements in psychology, behavioral economics, and neuroscience have shown the human pursuit of knowledge to be an essential aspect of human cognition. It drives intellectual development, is integral to social interactions, and is crucial for learning, decision-making, and goal-directed behavior. Information appears to be valuable in and of itself, even when it has no apparent use, whereas at other times, instrumental information is actively and paradoxically avoided. With this complex role, a wide range of neural mechanisms can be deployed to assign value to information and drive decisions to seek (or avoid) information. Evidence points toward key roles for the mesolimbic system and the prefrontal cortex in these processes. Specifically, two different networks appear to be involved in the implementation of information-seeking behaviors. One network, overlapping with areas involved in processing primary and monetary rewards, appears to drive a general preference for information, as well as valence-dependent information-seeking. The other network, independent of reward processing, is recruited when information is acquired to reduce uncertainty. In this chapter, we review some of the most recent discoveries in the field to provide an overview of the neural basis of information-seeking.

Over the past quarter of a century, scientists have attempted to answer the question of whether humans are unique in their self-reflective abilities, or whether versions of this might exist in nonhuman animals as well. This chapter explores the research on whether nonhuman primates (hereafter, primates) have the ability to monitor and control their own knowledge states, or metacognition. The chapter describes the two main paradigms that have traditionally been used to investigate this question, as well as their associated variations and limitations. This is followed by a summary of what has been found to date, with respect to metacognitive abilities across the primate order. The chapter concludes with a brief discussion of the questions that remain and areas for future investigation.