Developing methods to mitigate susceptibility to malevolent online communications

Turner, Nicola 2025. Developing methods to mitigate susceptibility to malevolent online communications. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Phishing and other forms of malevolent online communication pose a growing threat, yet defence strategies continue to rely heavily on technical solutions that cannot always fully protect users in dynamic, cognitively demanding environments. This PhD thesis investigates how contextual and cognitive factors shape individuals’ ability to discriminate between genuine and phishing messages, and develops interventions designed to support detection. Across eleven experiments involving more than 1,300 participants, the research adopts a controlled, laboratory-based Message Judgement Task (MJT) and applies Signal Detection Theory (SDT) to distinguish discrimination ability (d′) from response bias (c). The first experiment examined a broad range of demographic and affective predictors, showing that traits such as cognitive reflection, email proficiency, and age contribute small but reliable effects; while influence mechanisms such as reward framing and urgency also shape detection. Experiment 2 involved validating a novel MJT having incorporated email, SMS, and social media formats. Three experiments in Chapter 5 manipulated cognitive load using a task interruption (i.e. having attention taken away from the primary task) approach and demonstrated that discrimination improved when participants were engaged in demanding tasks, consistent with eustress effects or increased attention to diagnostic cues during breaks from difficult activity. In contrast, in Chapter 6’s motivational manipulations using financial incentives did not systematically alter discrimination, although response times differed between conditions, suggesting differences in processing strategy. Building on these insights, three information-salience interventions were developed and tested in Chapter 7 across four experiments. URL highlighting emerged as the most effective and robust, improving discrimination particularly for email and remaining effective across populations and under competing task demands. Overall, the PhD thesis demonstrates a series of novel and important findings. Prevalent to these are: that phishing susceptibility is highly context-dependent as well as trait-like; and interventions must align with platform-specific cues and real-world cognitive conditions. The findings offer both theoretical contributions to models of decision-making under load and practical implications for designing usable, cognitively compatible phishing defences.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Psychology
Date of First Compliant Deposit:	23 July 2026
Last Modified:	23 Jul 2026 15:46
URI:	https://orca.cardiff.ac.uk/id/eprint/188442

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