Ruscello D M, Shelton R L
J Speech Hear Disord. 1979 Nov;44(4):504-12. doi: 10.1044/jshd.4404.504.
Children misarticulating the /r/ or /s/ speech sounds or both were identified, and assigned randomly to one of two groups. Each group received speech lessons that were similar. However, during response acquisition training, Group 1 was requested to plan articulatory movements mentally, produce the target sound, and assess the production. Group 2 practiced the training units without using the planning and assessment procedures. Group 1 exceeded Group 2 on generalization measures when the planning and assessment training was in effect.