1 / 20

Spontaneous prosocial choice by chimpanzees

Spontaneous prosocial choice by chimpanzees. Horner et al. Background - Altruism. Altruism commonly seen in humans Chimps closest biological relative Contradiction between observational and experimental studies Altruistic or empathetic behaviors seen observationally (sharing food)

madge
Download Presentation

Spontaneous prosocial choice by chimpanzees

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Spontaneous prosocial choice by chimpanzees Horner et al.

  2. Background - Altruism • Altruism commonly seen in humans • Chimps closest biological relative • Contradiction between observational and experimental studies • Altruistic or empathetic behaviors seen observationally (sharing food) • Lack of consistent evidence for prosocial behavior in controlled experimental conditions • Two primary altruistic experimental methods • Giving Assistance Tests (GAT) • Prosocial Choice Tests (PCT)

  3. Background - Giving Assistance Tests • Choice between giving help or doing nothing • Giving an out-of-reach object for a human or conspecific • Provided a conspecific with a needed tool • Bonobos in particular show prosocial tendencies in GAT • Communication greatly increases chance of receiving needed help • Children similarly generally grant help only to vocal partners

  4. Background - Prosocial Choice Tests • Subject chooses between two outcomes that are identical to self • One choice rewards only self, the other rewards self and a peer • Chimps have not shown consistent preference for the prosocial choice • However other monkeys (e.g. capuchin monkeys) have shown prosocial preference

  5. Background – Current Study • Confounding factors may be responsible for lack of significant results • Complex testing apparatus • Distracting rewards • Limited contact between subject and partners • Horner et al.’s goal: reduce these extra factors

  6. Methods - Overview • Subject chooses a token from the bucket • Tokens represent either selfish or prosocial choice • Food given to either just subject, or both subject and partner, based on token

  7. Methods - Participants • 7 Adult female chimpanzees (6 in data) • All members of a long-established 12 chimp living group • All experienced in a token exchange program • Each chimp was tested with three different partners • One with a significantly affiliative relationship • One with a significantly negative relationship • One with a neutral relationship • Each subject given a preference tests, to control for any color preference in the tokens

  8. Methods – Contingency Training • Two participants were chosen and randomly designated as either the actor or the partner • Actor given a set of 10 tokens, 5 selfish and 5 prosocial (distinguished by differing color) • Experimenter requested them back one-by-one • Actor rewarded when giving any token back, partner rewarded when prosocial token given back

  9. Methods - PCT • Subject given tub filled with 30 tokens, 15 of each • Hands a token to experimenter, who puts token on easily visible platform, and replaces token in tub • Experimenter gives banana treat, wrapped in a noisy paper wrapping, to either the subject or the subject and partner • Partner can be easily seen and heard

  10. Methods – Control Trials • Subjects were run through experiment again, with identical procedures until the PCT, including preference test and contingency training • A new color scheme selected for tokens • PCT the same, except for the lack of a partner • If a prosocial token chosen, experimenter still pretends to give a food reward to an imaginary partner

  11. Results • Prosocialv.s. selfish token • Bias towards prosocial choice • No partner control group • chimps choose randomly

  12. Results

  13. Results • Found no correlation for choices based off of previous behavior when roles were reversed • High ranking chimps found to be more prosocial than subordinate apes • No significant difference between related individuals vs. non related • No correlation between prosocial behavior and outside affiliation (grooming pairs)

  14. Results- Actor/partner interactions • Chimps interacted frequently • Behavior of partner categorized as: • Neutral • Attention-getting • Direct requests and pressure (DRP) • Partners engaged in the non-neutral behaviors more often following selfish choices by the actor

  15. Results- Actor/partner interactions

  16. Results- Actor/partner interactions • Actors acted prosocial towards neutral partners, and even more prosocial towards attention-getting partners • Actors did not act differently from chance level for DRP partners

  17. Results- Actor/partner interactions

  18. Discussion • Chimps favor the prosocial option • Factors such as kinship, affiliation, dominance rank or reciprocity have no effects • Matches what chimps do in the wild when sharing a common goal

  19. Discussion • However, this study does have different results than other studies done in a lab • They believe this was due to • Close proximity • Wrapping the treats in paper • Avoiding complex apparatuses • Results also differ from popular suggestion that prosocial choices happen more often between related monkeys

  20. Discussion • They do acknowledge that chimps could be acting on reciprocity for events happening outside of the experiment • How do you think this could be controlled for?

More Related