Pilditch, TD; (2017) Communicated beliefs: The interplay of evidence and truth values in erroneous belief acquisition and maintenance. Doctoral thesis , UCL (University College London).

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Abstract

This thesis explores the interplay between evidence (in terms of clarity, quantity and order) and source factors in the uptake and maintenance of second-hand, erroneous beliefs. Through a series of online paradigms, we demonstrate the uptake of a communicated belief (e.g., “Option A is better than option B”) is conditional upon early experiences, given an unknown source. Further, we show that such a consolidation of belief then leads to a confirmation bias, wherein beliefs are maintained despite long-run contradictory evidence. Importantly, we demonstrate that such a bias occurs despite participants being motivated towards accuracy (as opposed to belief-maintenance), and the presence of counterfactual information. We accordingly forward an integrative confirmation bias account of consolidated belief maintenance. The focus then turns to explore the gatekeeping role of early experiences. Using short-term fluctuations in evidence, we not only demonstrate the impact of the first few pieces of evidence in consolidating beliefs, but that such effects are interruptible. Taking insights yielded from the Bayesian source credibility model, the perceived expertise and trustworthiness of the source are then manipulated in conjunction with initial evidence. In line with predictions, beliefs from credible sources show consolidation prior to initial evidence, subsuming its role. Conversely, beliefs from dubious sources once again demonstrate the critical impact of initial evidence. Findings are related to the role of source cues and early experiences in increasing the confidence in a belief’s validity, placed within the wider theoretical context, and novel implications for reliability updating are demonstrated. These empirical findings are then extrapolated to belief propagation in online networks using Agent-Based Modelling. This work demonstrates that the structure and incentives present in online networks exacerbate societal level erroneous belief uptake. Implications are drawn to literature including persuasion, placebo effects, and opinion dynamics, along with phenomena including superstition and pseudoscientific beliefs.

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