Raising the ceiling: the Tower of London--extended version.

The Tower of London (TOL) is a neuropsychological test used to assess problem-solving and planning skills. Clinically, the measure has demonstrated sensitivity in discriminating between performance among individuals with varying severity of closed head injury (CHI). However, ceiling effects have been demonstrated with preadolescent and adolescent CHI samples. An extended version of the Tower of London (TOL-E) was devised to minimize these ceiling effects. In this study we examined the performance of 26 normal children between the ages of 7 and 16 years on the TOL-E. Significant complexity and age effects suggest that the TOL-E contributes a significant level of complexity relative to the original TOL across all age groups. This finding has implications for the measure's ability to detect the development of planning and problem solving in normal children as well as to differentiate between impaired and nonimpaired samples.