This questionnaire assesses altruistic behaviour towards the co-participant and consists of three subscales: the Unconditional Everyday Altruism Scale, the Conditional Everyday Altruism Scale, and the Extreme Altruism Scale (Bressan et al., 2009). Each scale will be presented in a random order, with the items within each scale presented in a random order as well. --- ### Unconditional Everyday Altruism This questionnaire is concerned with your relationship with your co-participant. Try and answer each question as quickly and accurately as you can. [1 = Never, 2 = Once, 3 = More than once, 4 = Often, 5 = Very often] - I have given money to my co-participant without expecting to get it back. - I have let my co-participant borrow my car. - I have helped my co-participant move households. - I have taken my co-participant out to dinner without expecting to be taken out. - I have allowed my co-participant to stay with me rent-free. - I have given my co-participant things of value I no longer want or need, without expecting to get them back (entertainment equipment, furniture, clothing, etc.). - I have bought my co-participant gifts for birthdays and holidays without concern for how much they spend on me. - I have repeatedly granted emotional support for my co-participant, and would continue to do so regardless of their support for me. ### Conditional Everyday Altruism This questionnaire is concerned with your relationship with your co-participant. Try and answer each question as quickly and accurately as you can. [1 = Never, 2 = Once, 3 = More than Once, 4 = Often, 5 = Very often] - I have given money to my co-participant, only when I expected to get it back. - I have let my co-participant borrow my car, only after they have let me borrow theirs. - I have helped my co-participant move households, only after they have helped me. - I have taken my co-participant out to dinner, only when I have expected to be taken out at a later date, or reimbursed. - I have allowed my co-participant to stay with me, only if they offered to pay rent or had allowed me to stay with them. - I have given my co-participant things of value I no longer want or need, only with the understanding that I would get them back (entertainment equipment, furniture, clothing, etc.). - I buy my co-participant gifts for birthdays and holidays, only if I have received gifts from them. - I have repeatedly granted emotional support for my co-participant, only when they have shown support for me. ### Extreme Altruism This questionnaire is concerned with your relationship with your co-participant. Try and answer each question as quickly and accurately as you can. How likely is it that you would do the following: [1 = Not at all likely, 2 = A little likely, 3 = Somewhat likely, 4 = Very likely, 5 = Extremely likely] - Help your co-participant load furniture for a housing move? - Donate a pint of blood to reduce your co-participant's hospital costs? - Donate a kidney to your co-participant? - Loan your co-participant £500 for car repairs. - Give your co-participant a gift worth £100? - Co-sign a loan for your co-participant in the amount of £10,000? - Enter a burning building to assist your co-participant on the second floor? - Swim a 1/2 mile to perform a rescue on your co-participant. - Jump on a terrorist hand grenade to protect your co-participant, with a certainty of injury and 75% chance of death? ---- ### References Bressan, P., Colarelli, S. M., & Cavalieri, M. B. (2009). Biologically costly altruism depends on emotional closeness among step but not half or full siblings. *Evolutionary Psychology, 7*, 118-132.