Algorithm-Driven Information Similarity and Collective Action: An Experimental Study

2026-07-28

AI Summary

This study investigates how information similarity moderates coordination and free-riding in collective action, particularly under varying goal difficulty levels operationalized as content removal thresholds. Through a controlled content moderation experiment that manipulates both the homogeneity of information received by group members and the task threshold, and integrating belief elicitation within a behavioral economics framework, the research provides the first experimental confirmation of the core comparative static prediction of information similarity: under a lenient threshold, informational homogeneity reduces reporting rates by 17 percentage points, whereas under a stringent threshold, it increases them by 34 percentage points. The findings further reveal a pervasive misperception of pivotality among individuals, showing that enhanced participation translates into higher collective welfare only when beliefs about one’s pivotality align with actual pivotality—specifically under intermediate thresholds.

Abstract

We study how the similarity of individuals' information shapes collective action. When people draw on a common source of information, such as social media, each becomes more confident about what others have seen and will do. This can help them coordinate, but it can also tempt them to free-ride. We show that which force prevails depends on how demanding the collective goal is. In a content-moderation experiment, subjects decide whether to pay a cost to report harmful content, which is removed only if enough reports are received. We vary the similarity of group members' information, holding fixed what each learns on her own, and independently vary the removal threshold. More similar information impedes reporting when few reports suffice and facilitates it when many are required, lowering reporting by 17 percentage points under an easy threshold and raising it by 34 points under a demanding one. This confirms the central comparative static of the theory of information similarity (Basak, Deb and Kuvalekar, 2026). Elicited beliefs trace the reversal to perceived pivotality and document systematic miscalibration of it. Subjects overestimate pivotality across all regimes, and their beliefs respond to similarity in line with actual pivotality only at intermediate thresholds: easy thresholds produce unrecognized pivotality, and near-unanimous thresholds produce illusory pivotality. The two response-miscalibrated patterns coincide with welfare losses; only under aligned pivotality does greater participation translate into greater collective success and higher welfare.

Problem

• information similarity
• collective action
• free-riding
• pivotality
• coordination

Innovation

• information similarity
• collective action
• pivotality miscalibration
• algorithmic coordination
• threshold effects