This form of reciprocity is expressed by people who invest more resources in cooperation and punishment than what is deemed optimal based on established theories of altruism.
ðɪs fˈɔːɹm ʌv ɹᵻsɪpɹˈɑːsᵻɾi ɪz ɛkspɹˈɛst baɪ pˈiːpəl hˌuː ɪnvˈɛst mˈoːɹ ɹᵻsˈoːɹsᵻz ɪn koʊˈɑːpɚɹˈeɪʃən ænd pˈʌnɪʃmənt ðɐn wʌt ɪz dˈiːmd ˈɑːptɪməl bˈeɪst ˌɔn ɪstˈæblɪʃt θˈiəɹiz ʌv ˈɔːltɹuːˌɪzəm.