D1 Affective Polarization and Network Homophily

Topic

Three indicators measure the same dimension of group identity within this trajectory from different angles: affective polarization measures emotional hostility toward the out-group; network homophily measures the extent to which that out-group is avoided structurally; and perceived social distance measures the subjective experience of that same distance. All three tend to rise in tandem as group identity hardens; they are not independent measures.

The affective polarization index measures emotional hostility toward the out-group—distinct from mere disagreement over ideas; the widening gap between this hostility and such disagreement is the variable that directly triggers extreme affective polarization.

Network homophily measures the proportion of ties maintained within one’s own group versus those extending to the out-group; a sustained drop toward zero serves as a direct measure of a closed echo chamber—reflecting the near-total absence of cross-exposure characteristic of that phenomenon.

Surveys on perceived social distance measure how distant the out-group is perceived to be in terms of values ​​and interests; a sustained increase in this distance, combined with the perception of an existential threat to one’s own group, signals the violent radicalization of a subgroup—the most extreme of the three anomalies described here.

These three indicators do not merely rise together; each fuels the other two. Rising affective polarization reduces the ties people are willing to maintain with the out-group, thereby lowering network homophily; low network homophily eliminates the cross-exposure that might otherwise correct increasing perceived social distance; and widening perceived social distance, in turn, reinforces the emotional hostility measured by affective polarization.

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