RECIPROCATORS AND PROSOCIALS 1 European Journal of Personality, 2001, 15, S19-S35 Individual differences and social norms: The distinction between reciprocators and prosocials Marco Perugini University of Essex, United Kingdom Marcello Gallucci Free University of Amsterdam, The Netherlands Running Heading: RECIPROCATORS AND PROSOCIALS Address correspondence to: Dr Marco Perugini, Department of Psychology, University of Essex Wivenhoe Park, Colchester CO4 3SQ, United Kingdom email: mperug@essex.ac.uk; Tel. 01206 874330; Fax 0126 873590