Assessing the truthfulness of information is a critical task in fact-checking, and is typically performed using binary or coarse ordinal scales (2-6 levels), though fine-grained scales (e.g., 100 levels) have also been explored. Magnitude Estimation (ME) takes this approach further by allowing assessors to assign any value in the range (0, + ∞). However, it introduces challenges, including the need for aggregation of assessments from individuals with different interpretations of the scale. Despite these, its successful applications in other domains suggest its potential suitability for truthfulness assessment. We conduct a crowdsourcing study by collecting assessments on claims sourced from the PolitiFact fact-checking organization using ME. To the best of our knowledge, this is the first systematic investigation of ME in the context of truthfulness assessment. Our results show that while aggregation methods significantly impact assessment quality, optimal aggregation strategies yield accuracy and reliability comparable to traditional scales. More importantly, ME allows capturing subtle differences in truthfulness, offering richer insights than conventional coarse-grained scales.

This study challenges the prevailing approach of measuring political leanings in Large Language Models (LLMs) through direct questioning. By extensively testing LLMs with original, positively and negatively paraphrased Political Compass questions we demonstrate that LLMs do not consistently reveal their political biases in response to standard questions. Our findings indicate that LLMs' political orientations are elusive, easily influenced by subtle changes in phrasing and context. This study underscores the limitations of direct questioning in accurately measuring the political biases of LLMs and emphasizes the necessity for more refined and effective approaches to understand their true political stances.

Research on misinformation detection has primarily focused either on furthering Artificial Intelligence (AI) for automated detection or on studying humans' ability to deliver an effective crowdsourced solution. Each of these directions however shows different benefits. This motivates our work to study hybrid human-AI approaches jointly leveraging the potential of large language models and crowdsourcing, which is understudied to date. We propose novel combination strategies Model First, Worker First, and Meta Vote, which we evaluate along with baseline methods such as mean, median, hard- and soft-voting. Using 120 statements from the PolitiFact dataset, and a combination of state-of-the-art AI models and crowdsourced assessments, we evaluate the effectiveness of these combination strategies. Results suggest that the effectiveness varies with scales granularity, and that combining AI and human judgments enhances truthfulness assessments' effectiveness and robustness.

There is an important ongoing effort aimed to tackle misinformation and to perform reliable fact-checking by employing human assessors at scale, with a crowdsourcing-based approach. Previous studies on the feasibility of employing crowdsourcing for the task of misinformation detection have provided inconsistent results: some of them seem to confirm the effectiveness of crowdsourcing for assessing the truthfulness of statements and claims, whereas others fail to reach an effectiveness level higher than automatic machine learning approaches, which are still unsatisfactory. In this paper, we aim at addressing such inconsistency and understand if truthfulness assessment can indeed be crowdsourced effectively. To do so, we build on top of previous studies; we select some of those reporting low effectiveness levels, we highlight their potential limitations, and we then reproduce their work attempting to improve their setup to address those limitations. We employ various approaches, data quality levels, and agreement measures to assess the reliability of crowd workers when assessing the truthfulness of (mis)information. Furthermore, we explore different worker features and compare the results obtained with different crowds. According to our findings, crowdsourcing can be used as an effective methodology to tackle misinformation at scale. When compared to previous studies, our results indicate that a significantly higher agreement between crowd workers and experts can be obtained by using a different, higher-quality, crowdsourcing platform and by improving the design of the crowdsourcing task. Also, we find differences concerning task and worker features and how workers provide truthfulness assessments.

The increase of the amount of misinformation spread every day online is a huge threat to the society. Organizations and researchers are working to contrast this misinformation plague. In this setting, human assessors are indispensable to correctly identify, assess and/or revise the truthfulness of information items, i.e., to perform the fact-checking activity. Assessors, as humans, are subject to systematic errors that might interfere with their fact-checking activity. Among such errors, cognitive biases are those due to the limits of human cognition. Although biases help to minimize the cost of making mistakes, they skew assessments away from an objective perception of information. Cognitive biases, hence, are particularly frequent and critical, and can cause errors that have a huge potential impact as they propagate not only in the community, but also in the datasets used to train automatic and semi-automatic machine learning models to fight misinformation. In this work, we present a review of the cognitive biases which might occur during the fact-checking process. In more detail, inspired by PRISMA – a methodology used for systematic literature reviews – we manually derive a list of 221 cognitive biases that may affect human assessors. Then, we select the 39 biases that might manifest during the fact-checking process, we group them into categories, and we provide a description. Finally, we present a list of 11 countermeasures that can be adopted by researchers, practitioners, and organizations to limit the effect of the identified cognitive biases on the fact-checking activity.

To scale the size of Information Retrieval collections, crowdsourcing has become a common way to collect relevance judgments at scale. Crowdsourcing experiments usually employ 100–10,000 workers, but such a number is often decided in a heuristic way. The downside is that the resulting dataset does not have any guarantee of meeting predefined statistical requirements as, for example, have enough statistical power to be able to distinguish in a statistically significant way between the relevance of two documents. We propose a methodology adapted from literature on sound topic set size design, based on t-test and ANOVA, which aims at guaranteeing the resulting dataset to meet a predefined set of statistical requirements. We validate our approach on several public datasets. Our results show that we can reliably estimate the recommended number of workers needed to achieve statistical power, and that such estimation is dependent on the topic, while the effect of the relevance scale is limited. Furthermore, we found that such estimation is dependent on worker features such as agreement. Finally, we describe a set of practical estimation strategies that can be used to estimate the worker set size, and we also provide results on the estimation of document set sizes.