The role of System 1 and System 2 semantic memory structure in human and LLM biases

TL;DR

This study models human and LLM semantic memory structures to understand their roles in implicit biases, revealing key differences in how bias relates to memory structure in humans versus LLMs.

Contribution

It introduces a network-based approach to compare human and LLM semantic memory structures and their relation to implicit bias, highlighting fundamental cognitive differences.

Findings

Semantic memory structures are irreducible only in humans.

Lower bias levels are associated with System 2 structures in humans.

LLMs lack certain human-like conceptual knowledge affecting bias regulation.

Abstract

Implicit biases in both humans and large language models (LLMs) pose significant societal risks. Dual process theories propose that biases arise primarily from associative System 1 thinking, while deliberative System 2 thinking mitigates bias, but the cognitive mechanisms that give rise to this phenomenon remain poorly understood. To better understand what underlies this duality in humans, and possibly in LLMs, we model System 1 and System 2 thinking as semantic memory networks with distinct structures, built from comparable datasets generated by both humans and LLMs. We then investigate how these distinct semantic memory structures relate to implicit gender bias using network-based evaluation metrics. We find that semantic memory structures are irreducible only in humans, suggesting that LLMs lack certain types of human-like conceptual knowledge. Moreover, semantic memory structure relates consistently to implicit bias only in humans, with lower levels of bias in System~2 structures. These findings suggest that certain types of conceptual knowledge contribute to bias regulation in humans, but not in LLMs, highlighting fundamental differences between human and machine cognition.