When LLMs Manipulate: Measuring Behavioral, Social, and Temporal Effects
Organizations: Rensselaer Polytechnic Institute, USA · Independent Researcher, Colombia · National University of Sciences and Technology, Pakistan · Virginia Tech, USA
Abstract
Large language models (LLMs) can influence user trust and decision-making through subtle linguistic cues, yet the behavioral effects of manipulative outputs remain poorly quantified. We introduce a behavioral computing framework for measuring behavioral vulnerability, defined as users' susceptibility to manipulative AI responses. Building on DarkPatterns-LLM benchmark, we generate controlled manipulative stimuli using Manipulation Gradient Descent (MGD), targeting biases associated with authority, urgency, and social proof. We analyze participant responses using the Multi-Stakeholder Impact Assessment Network (MSIAN) to model cross-user influence and the Temporal Harm Propagation Model (THPM) to characterize the persistence of behavioral effects over time. In a study involving 120 participants, manipulative framing produced significant changes in trust calibration and compliance (), with effects also propagating across social contexts. These findings highlight the need to extend LLM safety evaluation beyond model outputs to measurable behavioral consequences and provide a computational framework for quantifying individual, social, and temporal risks arising from manipulative AI interactions.
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Appendix
| Condition | Low | Medium | High | Mean |
|---|---|---|---|---|
| Authority (A) | 0.41 | 0.58 | 0.74 | 0.58 |
| Emotional (E) | 0.37 | 0.53 | 0.69 | 0.53 |
| Social Proof (S) | 0.33 | 0.49 | 0.65 | 0.49 |
| Prosocial (P) | 0.29 | 0.46 | 0.63 | 0.46 |
| Control (C) | 0.22 | – | – | 0.22 |
| Condition | TRR | BPI ( ) |
|---|---|---|
| Authority | 0.42 | 0.61 |
| Emotional | 0.48 | 0.57 |
| Social Proof | 0.53 | 0.49 |
| Prosocial | 0.55 | 0.47 |
| Control | 0.68 | 0.32 |
Language Model Safety Evaluation
Language model safety evaluation measures harmful behavior, refusal, robustness, and over-refusal across realistic prompts, users, and deployment settings.
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