UC San Diego

Humans engage in self-talk, a phenomenon potentially unique to our species. Research indicates that inaudible self-talk (“inner speech”) and audible self-talk (“private speech”) together occupy up to a quarter of adults’ conscious time, influencing our mental well-being as well as cognitive functioning. While inner speech has traditionally been the primary research focus of adult cognition, its covert nature makes it hard to quantify. Therefore, most research in this area employs indirect data collection methods like self-reporting and verbal interference, which assesses the impact of self-talk by inhibiting it. However, the lack of precise quantification of self-talk prevents the accurate assessment of the strength of its effects. Private speech, another form of self-talk adults engage in, is often overlooked in research on adult cognition. However, private speech could offer unique insights into the cognitive impacts of self-talk due to its objective quantifiability.Chapter 1 delves into whether participants’ self-reports could validly inform comparisons between the impacts of inner and private speech on performance in a card-matching memory task. Specifically, I evaluated the reliability and accuracy of self-reported self-talk usage. Findings show discrepancies between objective and subjective private speech, which questions the viability of employing self-reports to precisely evaluate the effect of self-talk. Chapters 2 and 3 then focus on private speech due to its objective quantifiability and relative lack of study. In Chapter 2, participants' performance was repeatedly measured in two “Private Speech” trials, where they were instructed to complete the task (same as in Chapter 1) while using private speech extensively. We found that participants performed significantly better on trials for which they used more private speech, regardless of individuals’ baseline task competency. Chapter 3 reaffirms this positive association and further establishes causality between private speech usage and enhanced performance. Performance improvements from private speech were consistent across varying task difficulties but were most pronounced in people who habitually use private speech in their everyday lives. The consistent findings across the studies underscore the potential of private speech as a tool for adult cognition, offering significant insights for educational and instructional strategies.