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Primates Pass Dynamically Social Anticipatory-Looking False-Belief Tests

2020; Elsevier BV; Volume: 24; Issue: 10 Linguagem: Inglês

10.1016/j.tics.2020.07.003

1879-307X

Fumihiro Kano, Josep Call, Christopher Krupenye,

Psychology of Moral and Emotional Judgment

Three recent studies [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 2. Kano F. et al. Great apes use self-experience to anticipate an agent's action in a false-belief test. Proc. Nat. Acad. Sci. U. S. A. 2019; 116: 20904-20909 Crossref PubMed Scopus (64) Google Scholar , 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ], inspired by seminal work with human infants (e.g., [ 4. Southgate V. et al. Action anticipation through attribution of false belief by 2-year-olds. Psychol. Sci. 2007; 18: 587-592 Crossref PubMed Scopus (619) Google Scholar ]), have shown that non-human apes and macaques pass anticipatory-looking (AL) false-belief (FB) tests. These results raise the possibility that both apes and monkeys understand that others' actions are driven not by reality but by beliefs about reality, even when those beliefs are false. In response, Horschler et al. [ 5. Horschler D.J. et al. Do non-human primates really represent others' beliefs?. Trends Cogn. Sci. 2020; 24: 594-605 Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar ] argued that these findings 'should be interpreted cautiously due to methodological and theoretical challenges paralleling trends in the human literature.' We agree that continued work is necessary to identify factors that influence reproducibility of AL paradigms and also to specify the mechanisms and functions of the observed behaviors in primates. However, inferences from the human literature (summarized in [ 5. Horschler D.J. et al. Do non-human primates really represent others' beliefs?. Trends Cogn. Sci. 2020; 24: 594-605 Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar ]) should be made with caution because key non-human results have largely been replicated and extended across different groups and species [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 2. Kano F. et al. Great apes use self-experience to anticipate an agent's action in a false-belief test. Proc. Nat. Acad. Sci. U. S. A. 2019; 116: 20904-20909 Crossref PubMed Scopus (64) Google Scholar , 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ], so far providing a different picture from more variably replicable human studies. Moreover, non-human studies retain only the conceptual design of human paradigms with various improvements and optimization for non-human primates (Box 1). What we see as the more pressing – but potentially interwoven – matter is resolving discrepancies among comparative findings: apes and monkeys have passed AL-FB tests (visually anticipating that an agent would search for an object where she falsely believed it to be), but monkeys have not succeeded in violation-of-expectation (VoE) FB paradigms [ 6. Marticorena D.C.W. et al. Monkeys represent others' knowledge but not their beliefs. Dev. Sci. 2011; 14: 1406-1416 Crossref PubMed Scopus (85) Google Scholar ] (they do not look longer when an agent's search is inconsistent with her FBs). Here, we spotlight crucial methodological differences that may explain the unique success of non-human AL paradigms. In concluding, we discuss adaptive significance and future directions. Box 1Methodological Differences between Non-human and Human AL-FB StudiesNon-human AL-FB studies were optimized for non-human primates and improved based on criticism of original human AL designs, by: (i) counterbalancing the side in which key events occurred during familiarization and test [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 2. Kano F. et al. Great apes use self-experience to anticipate an agent's action in a false-belief test. Proc. Nat. Acad. Sci. U. S. A. 2019; 116: 20904-20909 Crossref PubMed Scopus (64) Google Scholar , 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ]; (ii) adopting multiscenario/trial designs to stabilize within-individual response variation [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ] (note that comparing individual differences across studies is therefore more meaningful than doing so within studies); (iii) using short movies involving dynamic social interactions [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 2. Kano F. et al. Great apes use self-experience to anticipate an agent's action in a false-belief test. Proc. Nat. Acad. Sci. U. S. A. 2019; 116: 20904-20909 Crossref PubMed Scopus (64) Google Scholar , 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ] and a training procedure [ 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ] to maintain attention and engagement; (iv) using familiar props (e.g., haystack, metal mesh, stone, door) and intuitive scenarios to aid non-human participants' understanding of characters' actions and goals [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 2. Kano F. et al. Great apes use self-experience to anticipate an agent's action in a false-belief test. Proc. Nat. Acad. Sci. U. S. A. 2019; 116: 20904-20909 Crossref PubMed Scopus (64) Google Scholar , 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ]; (v) presenting natural reaching and approach scenes that evoke AL to proximal targets; and (vi) using challenging conditions (e.g., FB2 condition of [ 4. Southgate V. et al. Action anticipation through attribution of false belief by 2-year-olds. Psychol. Sci. 2007; 18: 587-592 Crossref PubMed Scopus (619) Google Scholar ]) with fewer low-level explanations in all tests [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 2. Kano F. et al. Great apes use self-experience to anticipate an agent's action in a false-belief test. Proc. Nat. Acad. Sci. U. S. A. 2019; 116: 20904-20909 Crossref PubMed Scopus (64) Google Scholar , 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ]. It remains untested whether some of these changes could improve replicability in human AL-FB studies. Moreover, some parameters, such as optimal analysis windows of anticipatory looks (first looks and total looking duration), could be further evaluated in future human and non-human AL-FB tasks – although this should be optimized in each task rather than simply standardized across tasks because cognitive demands vary across tasks (e.g., [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 2. Kano F. et al. Great apes use self-experience to anticipate an agent's action in a false-belief test. Proc. Nat. Acad. Sci. U. S. A. 2019; 116: 20904-20909 Crossref PubMed Scopus (64) Google Scholar ]). Non-human AL-FB studies were optimized for non-human primates and improved based on criticism of original human AL designs, by: (i) counterbalancing the side in which key events occurred during familiarization and test [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 2. Kano F. et al. Great apes use self-experience to anticipate an agent's action in a false-belief test. Proc. Nat. Acad. Sci. U. S. A. 2019; 116: 20904-20909 Crossref PubMed Scopus (64) Google Scholar , 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ]; (ii) adopting multiscenario/trial designs to stabilize within-individual response variation [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ] (note that comparing individual differences across studies is therefore more meaningful than doing so within studies); (iii) using short movies involving dynamic social interactions [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 2. Kano F. et al. Great apes use self-experience to anticipate an agent's action in a false-belief test. Proc. Nat. Acad. Sci. U. S. A. 2019; 116: 20904-20909 Crossref PubMed Scopus (64) Google Scholar , 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ] and a training procedure [ 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ] to maintain attention and engagement; (iv) using familiar props (e.g., haystack, metal mesh, stone, door) and intuitive scenarios to aid non-human participants' understanding of characters' actions and goals [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 2. Kano F. et al. Great apes use self-experience to anticipate an agent's action in a false-belief test. Proc. Nat. Acad. Sci. U. S. A. 2019; 116: 20904-20909 Crossref PubMed Scopus (64) Google Scholar , 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ]; (v) presenting natural reaching and approach scenes that evoke AL to proximal targets; and (vi) using challenging conditions (e.g., FB2 condition of [ 4. Southgate V. et al. Action anticipation through attribution of false belief by 2-year-olds. Psychol. Sci. 2007; 18: 587-592 Crossref PubMed Scopus (619) Google Scholar ]) with fewer low-level explanations in all tests [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 2. Kano F. et al. Great apes use self-experience to anticipate an agent's action in a false-belief test. Proc. Nat. Acad. Sci. U. S. A. 2019; 116: 20904-20909 Crossref PubMed Scopus (64) Google Scholar , 3. Hayashi T. et al. Macaques exhibit implicit gaze bias anticipating others' false-belief-driven actions via medial prefrontal cortex. Cell Rep. 2020; 30: 4433-4444 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ]. It remains untested whether some of these changes could improve replicability in human AL-FB studies. Moreover, some parameters, such as optimal analysis windows of anticipatory looks (first looks and total looking duration), could be further evaluated in future human and non-human AL-FB tasks – although this should be optimized in each task rather than simply standardized across tasks because cognitive demands vary across tasks (e.g., [ 1. Krupenye C. et al. Great apes anticipate that other individuals will act according to false beliefs. Science. 2016; 354: 110-114 Crossref PubMed Scopus (340) Google Scholar , 2. Kano F. et al. Great apes use self-experience to anticipate an agent's action in a false-belief test. Proc. Nat. Acad. Sci. U. S. A. 2019; 116: 20904-20909 Crossref PubMed Scopus (64) Google Scholar ]).