"Transitional objects" as establishing operations for thumb sucking: a case study.

This study examines the effects of a "transitional object" (surgical cloth) on the thumb sucking of a 3-year-old boy in two conditions: while sitting in the lap of his physical therapist and while alone in his crib. Sucking occurred when the cloth was present and did not occur when it was absent, regardless of condition. These results are discussed in terms of establishing operations, object attachment, and application.