ɔːltˈɜːnətˌɪvli, ðɪ ɛkspˌɛɹɪmˈɛntəl ɡɹˈuːp kʊd biː ɹiːsˈɛntfəl ʌvðə kəntɹˈoʊl ɡɹˈuːp, ɪf ðɪ ɛkspˌɛɹɪmˈɛntəl ɡɹˈuːp pɚsˈiːv ɪts tɹˈiːtmənt æz ɪnfˈɪɹiɚ.
Alternatively, the experimental group could be resentful of the control group, if the experimental group perceive its treatment as inferior.