Model to be tested. We extend a by suggesting an additional behavioural mechanism, booking another appointment to donate (β), which enhances commitment to cooperate (Ø) and identity as a donor (π). Overall increased feelings of experienced warm glow increase the probability of booking, with this being stronger for warm cooperators (those with higher levels of experienced warm glow) than cool cooperators (those with lower levels of experienced warm glow). Booking (β) predicts return donation (ρ), which is again stronger for warm cooperators. An exogenous manipulation of warm glow/impure altruism will increase the probability of making another donation if a donor identity prime is present. As cool cooperators are less likely to book and have their donor identity strengthened, the warm-glow/impure-altruism-plus-identity messages should be maximally effective for cool cooperators. Green, behavioural mechanism; peach, psychological mechanism; brown, exogenous manipulation; light blue, overall experienced warm-glow; yellow, effects linked to being a warm-cooperator; dark blue, effects linked to being a cool cooperator; greys, indications of associated behaviours or action.
