Private Speech in Illiterate Adults: Cognitive Functions, Task Difficulty, and Literacy

Children's private speech has been widely studied among children, but it is clear that adults use pri- vate speech as well. In this study, illiterate adults' private speech during a ''school-like'' task was explored as a function of literacy level and task difficulty in a sample of 126 adults enrolled in a public literacy program. A main effect for literacy level was found—private speech was more internalized and less externalized among adults with higher literacy levels. Externalized private speech was more frequently observed among illiterate adults engaged in the most difficult task. Private speech served cognitive functions as indicated by the proportion of self-regulatory private speech and the proportion of private speech pre- ceding actions being higher in the advanced literacy group and among illiterate adults doing the easier task. Internal- ized private speech, self-regulatory private speech, and private speech preceding action were each positively cor- related with performance and negatively correlated with time to complete the task. The use of private speech in illiterate adults appears to be linked to the mastery of cultural experiences, such as literacy, similar to the self- talk of children.