An image score updates only when one acts as donor, not as recipient.

Evidence

Imagine a population of individuals with the option to help one another or not. Random pairs of players are chosen, of which one is the potential donor of some altruistic act and the other is the recipient. The donor can cooperate and help the recipient at a cost c to himself, in which case the recipient receives a benefit of value b (with b . c). If the donor decides not to help, both individuals receive zero pay-off. Each player has an image score, s, which is known to every other player. If a player is chosen as a donor and decides to cooperate then his (or her) image score increases by one unit; if the donor does not cooperate then it decreases by one unit. The image score of a recipient does not change. — Nowak, M. A., & Sigmund, K, Evolution of Indirect Reciprocity by…, 36

Categorization

• DEFINE: Formalizes the image-scoring mechanism: contributions to one’s score come only from donating, making the score a pure measure of generosity.
• XREF: Directly parallels the reader’s framing of Hester’s scarlet A as a fixed visible image score; the asymmetry (recipients don’t change score) maps to Dimmesdale’s secret transgression never entering the scoring system. — connects to: Donor-specific image scoring sustains cooperation while self-only strategies fail — Nowak, M. A., & Sigmund, K, Evolution of Indirect Reciprocity by…, 73

Related

• Donor-specific image scoring sustains cooperation while self-only strategies fail (similarity 0.85)
• Cooperation in image-scoring populations requires only about two interactions per player per lifetime. (similarity 0.83)
• Unconditional cooperators must be modeled separately from image-scoring discriminators. (similarity 0.82)
• A two-level analytical image-scoring model can be solved rather than simulated (similarity 0.82)
• Nowak, M. A., & Sigmund, K — Evolution of Indirect Reciprocity by Image Scoring (similarity 0.80)
• Discriminator strategies base aid on recipients’ most recent recorded move. (similarity 0.79)

Broader Connections

• Donor-specific image scoring sustains cooperation while self-only strategies fail #expands (0.85) — Nowak, M. A., & Sigmund, K, Evolution of Indirect Reciprocity by…, 73