It is a widely held view that “nobody knows you better than yourself.” However, the low validity of self-estimates of intelligence and other abilities indicated by a considerable body of research does not support this notion. Individuals overestimate themselves and do so particularly for domains in which they perform poorly (the so-called Dunning-Kruger effect). Interestingly, intelligence estimates given by others are equally accurate or sometimes even more accurate than self-estimates. This chapter provides an overview of research on self- and other-estimates of intelligence and potential moderators of their accuracy. It also aims to bring the research lines on self- and other-estimates of intelligence together within the framework of the self-other knowledge asymmetry (SOKA) model proposed by Simine Vazire. The ability to predict for which intelligence subfactors one of the two perspectives might provide more accurate estimates has implications for both research and practical fields like vocational counseling.

BASIC INFORMATION PROCESSING AND INTELLIGENCE

Research on individual differences in human cognitive abilities or intelligence has a long history in scientific psychology. After decades of psychometric research into the structure of human cognitive abilities, the last 20 to 30 years have been characterized also by attempts to analyze cognitive components and correlates of psychometric intelligence. In this realm an important approach has been the attempt to relate the individual speed of information processing to psychometric intelligence (the so-called mental speed approach). This approach traces back to the idea that human cognitive or intellectual functioning might be decomposed in elementary cognitive processes, which are assumed to constitute an important basis of intellectual functioning. In the last two decades important progress has been made in this field of research: In using so-called elementary cognitive tasks (ECTs), which put only minimal requirements on the participants and are, thus, less likely prone to differential strategy usage, dozens of studies have provided converging evidence that shorter reaction times in these tasks are associated with higher psychometric intelligence, indicating a higher speed of information processing in brighter individuals.

The ECTs that have been used most extensively in this field of research are the Hick and the inspection time (IT) paradigm (see Fig. 1a). In the IT paradigm (cf. Vickers, Nettelbeck, & Wilson, 1972) participants are tachistoscopically (i.e., for very short exposure durations) shown two vertical lines of different length. Immediately after their exposure, the lines are masked by two thicker vertical lines of equal length.