Overt and covert verbalization in normal and learning disabled children's problem solving.

The problem-solving ability of 18 learning-disabled high school students was increased by instructions to verbalize overtly, but not by instructions to verbalize their actions covertly. This suggests that Vygotsky's 1962 "internalization-of-speech" perspective may be as useful in understanding the limitations of disabled learners as it has been in understanding the limitations of young learners.