Functional Independence and Preference Effects O. Pino, D. Leone, S. Forconi, F. Casarini 82               Olimpia Pino *, Daniele Leone **, Sara Forconi * and Fabiola Casarini* * Department of Psychology, University of Parma, Italy ** J. Piaget Human Sciences Academy, Santa Maria C.Vetere, CE, Italy ABSTRACT he aim of the present study is to evaluate the effects of mand and tact establishment on collateral response in functionally different conditions among typically developing children. The influence of both mand and tact trainings on spontaneous utterance emergence was also examined by evaluating the role of preference. Data were collected within A-B-A and A-B-A-B1 multi-schedule across subjects’ designs. Six children with typical abilities were trained either to mand or tact the items ranked as highest and lowest in a preference assessment and subsequently tested to see if responses occurred in collateral conditions. Results show that all participants rapidly manded for preferred and neutral stimuli but acquired tact slowly suggesting that, although preference can be considered a strong motivative variable, other contingencies may alter verbal production. The role of stimulus preference and operants independence needs to be further investigated in consideration of the natural changes in its value during the experimental history. Key words: verbal behavior, mand/tact, operant independence, preference. T