Gaertner, S. L., Mann, J., Murrell, A. & Dovidio, J. F. (1989). Journal of Personality and Social Psychology, 57(2), 239–249.
Not read. The summary is drawn from the abstract or from what the work is standardly cited for. A reading should check it first.
Why this is here
Cited by Turner et al. 1994 (NOTE-1284) for the widening of self-categorization, and the experimental origin of the common in-group identity model behind Biel (NOTE-1299).
Read in its place
The work cannot be read here, so the record holds it at second hand.
Dovidio et al. 2009 (NOTE-1286) report the experiment in one sentence (p. 194): against a two-group condition, decategorization reduced bias by making former in-group members less attractive, and recategorization by making former out-group members more attractive. They also say the 1997 helping study used a procedure “similar to” its group manipulation. Missing still: the design, the manipulations, the samples, the bias measures and every number.