PhD Candidate, Computer Science
Northeastern University · Khoury College of Computer Sciences
I build AI systems that form and maintain accurate models of the people they interact with (their goals, capabilities, beliefs, and affective states) rather than relying on assumed, static, or one-size-fits-all models of the user.
Grounded in computational psychology and Theory of Mind, my work asks how the fidelity of a system's model of a person governs collaboration, trust, and decision-making, studied across five settings:
Ph.D. in Computer Science
Sept 2023 – May 2028 (exp.)B.S. in Data Science & Cognitive Psychology
Sept 2019 – May 2023Thesis direction: accurate modeling of users (Theory of Mind) as the basis for trustworthy human–AI interaction.
Designed grid-world delivery experiments showing that behavioral implicit communication (BIC) under an inaccurate capability model triggers a "conformity trap": humans defer to the robot's signaled plan, reinforcing its wrong assumptions. Developed a capability-elicitation framework that recasts alignment as an exploration–exploitation problem, where targeted probing accelerates convergence to an accurate human model and improves team performance.
Built the GAMBiT Theory-of-Mind Defender Agent, a PsychSim-based model that infers a network attacker's latent cognitive vulnerabilities from behavior alone. It maintains alternative explicit mental models, each a candidate bias (loss aversion, base-rate neglect, confirmation bias, sunk-cost, availability) with its own utility function, and updates a probability distribution over them as it observes attacker actions, enabling counterfactual reasoning to drive deception and defensive strategy. Validated in human-subject experiments (n = 61) in a simulated enterprise network.
Built a web-based escape room and ran an affect-labeling vs. control study identifying behavioral inflection points where unresolved negative affect predicts behavioral collapse, while resolved affect tracks efficient completion, grounding the design of affect-aware interventions that detect bounded-rationality signatures under emotional load.
Co-designed the Virtual Human Improv Library, a multi-agent (Orchestrator / Director / Actor) LLM framework for social-skills training through improvised role-play, grounded in Stanislavsky's Active Analysis and framing improvisation as real-time Theory of Mind practice.
Analyzed a 10-month LLM-based ticket-routing deployment at a fintech firm to show that automation relocates rather than eliminates articulation work, surfacing how teams negotiate ownership of ambiguous work.
Founding Engineer · Elevare
Apr 2026 – Present- ·Building an agentic orchestration layer that operationalizes evidence-based maternal interventions at scale, built on a clinical protocol engine, a safety-critical agentic architecture, and human-on-the-loop operations to improve personalization and early risk detection with every mother served.
- ·Building the product 0→1: scoping the technical roadmap, defining milestones, and standing up the engineering org's SOPs and tooling stack.
Applied AI/ML Fellow · Advisor360°
Sept 2025 – Apr 2026- ·Shipped an LLM + RAG Slack triage system to reduce ticket time-to-resolution and overall volume across production and non-production workflows.
- ·Translated developer interviews into a routing policy and an internal service-to-team mapping to power an auto-assignment agent achieving ~80% routing accuracy.
- ·Developed an interactive analytics and retrieval agent that summarizes recurring issues and recommends resolutions via embedding-based matching to historically resolved tickets.
Data Science Researcher · MITRE
May 2022 – Jun 2023- ·Automated the National Imagery Interpretability Rating Scale (NIIRS) evaluation workflow in Python, replacing manual scoring with a reproducible ML pipeline.
- ·Built a predictive model of tracker performance using motion-imagery quality factors, validated on held-out sequences; results peer-reviewed and published at IEEE AIPR.
Research Assistant · Simmons University
Jul 2022 – Jun 2023- ·Annotated 500+ utterances with PoLaR and supported a prosody-to-intent pipeline in R, extracting prosodic features (pitch, intensity, duration) and training supervised models.
- ·Ran feature ablations to quantify contributions of rhythm, stress, and intonation to speaker-intent understanding.
- Hirschmann, S., & Marsella, S. From Implicit to Encoded: How LLM-Based Ticket Routing Reshapes Coordination Practices in a Distributed Engineering Team. Under review, ACM CSCW 2027.
- Affect Labeling and Decision-Making in a Virtual Escape Room: A Behavioral Study. Under review, ACII 2026.
- Hirschmann, S., & Marsella, S. (2026). Aligning Teams across the Human–Artificial Divide: Optimizing Collaboration through Strategic Implicit Communication. International Conference on Human-Agent Interaction (HAI 2026). First author
- Dincer, B., Hirschmann, S., & Marsella, S. (2026). Towards a Virtual Human Improv Troupe for Social Skills Training. International Conference on Intelligent Virtual Agents (IVA 2026).
- Beltz, B., et al. (incl. Hirschmann, S., & Marsella, S.) (2026). Guarding Against Malicious Biased Threats (GAMBiT): Experimental Design of Cognitive Sensors and Triggers with Behavioral Impact Analysis. Computational Brain & Behavior (Springer).
- Hirschmann, S., Tanis, J., Irizarry, N., Martin, B. A., Brennan, M., & Irvine, J. M. (2022). The Relationship Between Tracking Performance and Video Quality. IEEE AIPR Workshop. First author
- Taylor, J., Noboa, N., Hirschmann, S., Tanis, J., Brown, P., & Irvine, J. M. (2023). Investigations into Image Interpretability for Machine Learning.
- Hirschmann, S., Yongsatianchot, N., & Marsella, S. (2024). Theory of Mind in Human-Robot Task Collaboration. CHI 2024 Workshop on Theory of Mind in Human-AI Interaction. First author
- Hans, S., Marsella, S., Hirschmann, S., & Gurney, N. (2025). Security Logs to ATT&CK Insights: Leveraging LLMs for High-Level Threat Understanding and Cognitive Trait Inference. arXiv:2510.20930.
- Hans, S., Gurney, N., Marsella, S., & Hirschmann, S. (2025). Quantifying Loss Aversion in Cyber Adversaries via LLM Analysis. arXiv:2508.13240.
- Carney, S., Hans, S., Hirschmann, S., Marsella, S., Fonken, Y., Wu, P., & Gurney, N. (2025). Detecting Ambiguity Aversion in Cyberattack Behavior to Inform Cognitive Defense Strategies. arXiv:2512.08107.
- Kim, R., Carney, S., Fonken, Y., Hans, S., Hirschmann, S., Marsella, S., Wu, P., & Gurney, N. (2025). Risk Psychology & Cyber-Attack Tactics. arXiv:2510.20657.