An Inexpensive Habituation and Sensitization Learning Laboratory Exercise Using Planarians

Abstract

We describe an inexpensive laboratory exercise that uses planarians to demonstrate habituation and sensitization. Students drop water from an eyedropper onto a planarian's anterior region and observe its contraction responses. Initially, students practice the procedure until attaining high interobserver reliability in scoring the degree of contraction. Subsequently, they measure the decline in responsivity that occurs over repeated stimulus presentations. Following habituation, the planarian is drawn in and out of the eyedropper several times, resulting in sensitization and dishabituation of the contractile response in accordance with dual-process theory (Groves & Thompson, 1970). This procedure can also be used to demonstrate spontaneous recovery and short-versus long-term habituation processes.