They tend to help less if they see non-cooperativeness by others, and this effect tends to be stronger than the opposite effect of seeing cooperative behaviors.
ðeɪ tˈɛnd tə hˈɛlp lˈɛs ɪf ðeɪ sˈiː nˈɑːŋkoʊˈɑːpɚɹətˌɪvnəs baɪ ˈʌðɚz, ænd ðɪs ɪfˈɛkt tˈɛndz təbi stɹˈɔŋɡɚ ðɐn ðɪ ˈɑːpəzˌɪt ɪfˈɛkt ʌv sˈiːɪŋ koʊˈɑːpɚɹətˌɪv bᵻhˈeɪvjɚz.