“…Several studies back up the role of some crucial variables of aggressive behaviour in applied educational and clinical settings: contingent attention upon aggressive responses, even in the form of reprimands, if the person has been deprived of social reinforcement; escape from aversive contingencies such as instructions or task demands; and acquisition of tangible reinforcers contingent on aggressive responses (Borrero et al, 2002;Carr et al, 1980;Iwata et al, 1994;Keller and Schoenfeld, 1979;Mace et al, 1991;Thompson and Iwata, 2001;Ò Reailly, 1995;Skinner, 1969;Ulrich, 1980). In addition, parental neglect in teaching compliance, triggers aversive and coercive interactions that increase antisocial responding as a result of chained contingencies of negative reinforcement; furthermore these behaviours generalise to school and peer contexts, where new strengthening contingencies appear (Biglan, 1995a, b;Coyne and Wilson, 2004;Huesmann et al, 2002;Kazdin and Buela, 1999;Knutson et al, 2004;Lipsey and Derzon, 1998;Mayer, 1995;Pakaslahti et al, 1996;Patterson, 1982Patterson, , 1986. Regarding adult subjects, Ullman and Krasner (1969) concluded that some possible factors underlying antisocial and psychopathic behaviours were: absence of a reinforcement history through which others become positive social reinforcers; insufficient training for performing appropriate social behaviour; to have been widely and physically punished; and positive reinforcement for performing antisocial behaviours from family and peers.…”