Validation of the Pethna toy through changes in collateral behaviours.

The Pethna toy is a recently developed toy designed for people with severe and profound mental handicaps. It delivers sensory consequences for the use of simple manipulanda. Two experimental studies evaluated the Pethna toy by monitoring changes in multiple, collateral behaviours. Experiment I demonstrated statistically significant decreases in turn away and stereotyped behaviour and increases in smiling. Experiment II demonstrated highly idiosyncratic changes in collateral behaviours in three adults with multiple handicaps. In all cases, turn away decreased. The role of response-response relationship, subject attention and relationship of sensory behaviours to stereotypies are discussed.