2 ֓ཁ How digital media drive affective polarization through partisan sorting (PNAS 2022) Peter Törnberg (Unveristy of Amsterdam) l Proceedings of the National Academy of Sciencesͱ͍͏༗໊δϟʔφϧ͔Βग़൛͞Εͨจ l Peter TörnbergࢯʹΑΔ୯ஶ l ΞϜεςϧμϜେֶॴଐɻ l ෳࡶܥίϯϐϡʔλʔαΠΤϯεΛ༻͍ͨɺཧۭؒʹ͓͚ΔۃԽϑΣΠΫχϡʔεͷੳʹैࣄ l 1-P4 POFl&DIPDIBNCFSTBOEWJSBMNJTJOGPSNBUJPO.PEFMJOHGBLFOFXTBTDPNQMFY DPOUBHJPOzͳͲ͕༗໊ l ͲΜͳจʁ ιʔγϟϧϝσΟΞͳͲͰݟΒΕΔۃԽ͕ରҙݟʹ৮Εͳ͍͜ͱʹΑΔΤίʔνΣϯόʔʹΑͬͯੜ͡Δͷ Ͱͳ͘ɺΉ͠ΖɺιʔγϟϧϝσΟΞʹΑͬͯ֎ͷਓʑͱަྲྀ͢ΔΑ͏ʹͳΓ֤Ҭʹ͓͍ͯଘࡏͨ͠ଟ༷ੑ͕ ୯७ͳೋۃͱz4PSUJOHz ͞ΕΔ͜ͱΛΦϐχΦϯμΠφϛοΫεͱ͍͏ख๏Λ༻͍ͯݕূ
3 ४උ エコーチェンバー from: Cossard, Alessandro, et al. "Falling into the echo chamber: the Italian vaccination debate on Twitter." Proceedings of the International AAAI conference on web and social media. Vol. 14. 2020. from: Wikipeida l ൃ৴͞ΕͨϝοηʔδΛ֦େ͠ɺ͕དྷͳ͘ͳΔՄೳੑΛ࣋ͭࣅͨͷಉ࢜Ͱܨ͕ͬͨด ͟͞Εۭͨؒͷ͜ͱ l ରཱ͢ΔϢʔβάϧʔϓͷҙݟ͔Βݽཱ͢ΔΤίʔνΣϯόʔೋۃԽͷओͳཁҼʢͱߟ ͑ΒΕͯΔʣ l ภͬͨใҰ෦ͷάϧʔϓͰϑΣΠΫχϡʔε͔ΓྲྀΕΔͳͲѱӨڹ
7 エコーチェンバーによって分極化が⽣じていることへ疑問 ४උ l ରҙݟͷίϯςϯπΛڞ༗͠ͳ͍͕ɺରҙݟʹ;ΕΔ PSԠ͢Δ͜ͱසൟʹੜ͡Δ l ΞϝϦΧɺΠεϥΤϧ྆ࠃʹ͓͍ͯҟͳΔҙݟͷχϡʔεΛආ͚͓ͯΒͣɺ৮ΕΔ͜ͱͰ͔͑ͬͯภ ޫΛڧΊΔ͜ͱΛࣔࠦ ・Implications of pro-and counter attitudinal information exposure for affective polarization., Hum. Commun. Res., (2014). ・Exposure to opposing views on social media can increase political polarization. Proc. Natl. Acad. Sci., (2018). ・Tweeting from left to right: Is online political communication more than an echo chamber? Psychol. Sci. 26, 1531–1542 (2015). ・Of echo chambers and contrarian clubs: Exposure to political disagreement among German and Italian users of Twitter. Soc. Media Soc. 2, 1–24 (2016).
8 Partisan Sortingが⽣じている可能性 ४උ l σδλϧϝσΟΞަྲྀΛଅ࣏͠తͳݴ͍૪͍ʹר͖ࠐΉ͜ͱͰɺͲͪΒͷཱʹཱ͖͔ͭΛٻ ΊΔޮՌΛ࣋ͭ ಛʹ࠷ۙͷΞϝϦΧ
l ΞϝϦΧͷେౘ࣏తͳͷ͚ͩͰͳ͘ɺফඅߦಈݸਓͷಓಙ·Ͱٵऩ͠zDVMUVSFXBSzΛ Ҿ͖ى͍ͯ͜͠Δ "GGFDUJWF1PMBSJ[BUJPOͱͷؔ࿈
l ଟ༷ͳࣾձΞΠσϯςΟςΟΛΧόʔ͠ɺͭͷΞΠσϯςΟςΟʹׂ͢Δͱ͍͏ΞϝϦΧࣾձͷ࠷ ۙͷ ・ L. Mason, Uncivil Agreement: How Politics Became Our Identity (University of Chicago Press, 2018). ・ N. McCarty, K. T. Poole, H. Rosenthal, Polarized America: The Dance of Ideology and Unequal Riches (MIT Press, 2016). ・A. Guess, B. Nyhan, B. Lyons, J. Reifler, Avoiding the echo chamber about echo chambers. Knight Foundation 2, 1–25 (2018). ・ M. Hetherington, J. Weiler, Prius Or Pickup?: How the Answers to Four Simple Questions Explain America’s Great Divide (Houghton Mifflin, 2018).
10 0QJOJPO%ZOBNJDT Opinion Dynamics l ߹ҙܗରཱͳͲʹࢸΔ·Ͱʹੜ͡Δɺݸਓؒͷ ҙݟٞͷਪҠΛϞσϦϯά͢ΔͨΊͷख๏ l ࣾձͷ߹ҙܗબڍͳͲͷԠ༻ʹ׆༻͞ΕΔ l ҙݟΛ࣋ͭݸਓͱަྲྀ͢Δ͜ͱͰɺ֤ݸਓͷ࣋ͭ ҙݟ͕มԽ͍ͯ͘͠ͱ͍͏ݱΛཧϞσϧʹ Αͬͯදݱͨ͠ͷ l ࠓճͷݚڀͰɺ0QJOJPO%ZOBNJDTΛ༻͍ͯ 1BSUJTBO4PSUJOH͕ͲͷΑ͏ͳঢ়گͰੜ͡Δͷ͔ Λݕূ
20 ·ͱΊ l 1PMBSJ[BUJPOͷจݙ͔ΒɺۃԽΛੜ͡Δ͜ͱΛઆ໌͢ΔΤίʔνΣϯόʔͱҟͳΔ ԾઆΛఏࣔ l ଞͷࢹʹ৮ΕΔ͜ͱ͕ແ͘ͳΔΤίʔνΣϯόʔͰͳ͘ɺ֎෦ͱަྲྀ͢Δ͜ͱͰೋۃԽ ͕ੜ͡Δ͜ͱΛઆ໌͢ΔͨΊͷϞσϧΛఏҊ l ہॴతͳ૬ޓ࡞༻͕ϝΠϯͰ͋Ε༷ʑͳҬͰ࣏จԽ͕ੜ͡ΔɺҰํͰɺ֎෦ͱͷ૬ޓ࡞༻͕ଟ͘ͳΕ ֤Ҭͷ࣏จԽ͕݁ͼ͖ͭ୯Ұͷౘత྾͕ੜ͡Δ l ౘੑ͕ଟ͘ͷ࣏తཱจԽతᅂΛؚ༗͢ΔΑ͏ʹͳΔ݁Ռɺఢରऀʹର͢Δෆ৴ ݏѱΛಛͱ͢ΔೋۃԽ͕ੜ͡Δ͜ͱɺͭ·Γ"GGFDUJWF1PMBSJ[BUJPOΛࣔࠦ l &DIP$IBNCFSͱҟͳΔԾઆɾઆ໌ϞσϧͷఏࣔΛߦͬͨͷͰɺೋۃԽͷ࣮ࡍͷσʔλ ʹద༻Մೳ͔Ͳ͏͔ͷݕ౼͕ࠓޙඞཁͦ͏