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Samantha Croffut & Mary Alice Davis

What’s in it for me? Self-regard precludes altruism and spite in chimpanzees (Jensen, Hare, Call & Tomasello 2006). Samantha Croffut & Mary Alice Davis. Introduction. 4 ways to interact Altruism Mutualism Selfishness Spite. Introduction. Humans unique – altruism & spite

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Samantha Croffut & Mary Alice Davis

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  1. What’s in it for me? Self-regard precludes altruism and spite in chimpanzees (Jensen, Hare, Call & Tomasello 2006) Samantha Croffut & Mary Alice Davis

  2. Introduction • 4 ways to interact • Altruism • Mutualism • Selfishness • Spite

  3. Introduction • Humans unique – altruism & spite • Concern for others & fairness as motivators • Correct inequitable gains • Maybe chimps? • Brosnanet al (2005) - averse to disadvantageous inequity • confounds

  4. Introduction • Silk et al. (2005) • Mutualism (1/1 payoff) or selfishness (1/0 payoff) • Not averse to inequity; no difference in choice • May not have understood their choices

  5. Introduction • Experiment 1 • Mutualism or selfishness • Experiment 2 • Altruism or weak spite • Experiment 3 • Altruism and true spite

  6. Apparatus and Setup Control Room – here, not shown in this figure

  7. Pre-Test Procedures • Preference probe (figure a) • Do subjects prefer particular cup? • Knowledge probe (figure b) • Do Ss understand consequences? • Control (figure c) • Choose 1 (of 4) banana cups • Expect random selection.

  8. Experimental Conditions

  9. Subjects (Actors & Recipients)

  10. Experiment 1: Mutualism and Selfishness Do chimpanzees prefer selfish or mutualist feeding strategies?

  11. Experiment 1: Subjects • Actors: 4 female, 1 male chimpanzees • Recipients: Alpha male & 5 yr male (lowest ranking) • Actors tested with each recipient

  12. Experiment 1: Test • Actor can reach only inner cup of either table • Recipient can reach outer cup of accessible table if actor chooses this table

  13. Experiment 1: Results Data collapsed – no session, recipient, or testing order effects Recipient’s presence or absence did not influence actors’ choices. Pull choices Grey = accessible table Black = inaccessible table

  14. Discussion - Experiment 1 • Knowledge probe - knew how apparatus worked • No difference between control and test conditions • Side bias or mutualistic? • Not selfish • Not adverse to disadvantageous inequity

  15. Experiment 2: Altruism and Weak Spite Will chimpanzees choose altruism (no reward) or withholding (no bananas to either)?

  16. Experiment 2: Methods • Actors: 9 female, 2 male chimpanzees • Bananas only in outer cups  no bananas for actor/recipient or recipient only gets banana

  17. Experiment 2: Results Data collapsed (no order or recipient effects) Kin made fewer choices. Altruistic and spiteful choices not affected. Pull choices Grey = accessible table Black = inaccessible table White = no choice

  18. Discussion - Experiment 2 • No difference between test and control conditions • Neither altruistic nor spiteful • Not other-regarding or averse to disadvantageous inequity? • Knowledge probe trials significant • Kinship had no effect

  19. Experiment 3: Altruism and Spite Will chimpanzees actively prevent recipients from getting banana treats?

  20. Experiment 3: Test • Actors: 5 female, 1 male chimpanzees • If actor does nothing* (15-25s)  recipient gets banana • If actor pulls inaccessible table  no bananas for either • *If actor does not pullinaccessible table rope,person moves (10 s)accessible table torecipient. • During move,actor able to pullinaccessible table,preventing recipient’s banana acquisition.

  21. Experiment 3: Results Data again collapsed Kinship (with alpha male) does not affect “doing nothing” or pulling away from or towards recipient. Pull choices Grey = accessible table Black = inaccessible table White = no choice

  22. Discussion - Experiment 3 • No difference between control and test conditions • Lack of other-regard or tolerance of disadvantageous inequity aversion? • 2 subjects appeared altruistic • Most likely selfish motivation

  23. Chimps indifferent to payoffs for conspecifics No difference mutualism & selfishness No difference altruism & weak spite No difference altruism & spite Pull choices Grey = accessible table Black = inaccessible table White = no choice

  24. Discussion - Overall • Chimps not other-regarding • Indifferent to inequity in food-acquisition context • Contrasts with Brosnan et al. (2005) • 14/20 refused food < 2% of time • Market-like exchange • No evidence of anger (as occurs in humans)

  25. Discussion - Overall • Chimps focus on self • Differs from humans • Features of cooperation arose within last 6 million years of human evolution

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