IC-1134LLMs show strong confirmation bias in multi-source settings, preferring evidence consistent with parametric memory, with stronger bias for popular entities
Jian Xie, Kai Zhang, Jiangjie Chen, Renze Lou, Yu Su
When both parametric memory and counter-memory are presented as evidence, LLMs systematically prefer the evidence consistent with their parametric memory. GPT-4 shows an 80% memorization ratio for the most popular PopQA questions, indicating stronger confirmation bias for well-known facts. The memorization ratio increases monotonically with the proportion of parametric memory evidence, from near 0% at 0/2 to near 100% at 2/2, but even at 1/2 (50/50) the ratio exceeds 50% for most models, confirming a genuine bias toward parametric memory.
Evidence
correlational
Key metric
GPT-4 memorization ratio 80% for most popular questions; at 1/2 proportion: ChatGPT 43.0, GPT-4 65.4, PaLM2 56.8, Qwen-7B 52.3, LLaMA2-7B 58.4, LLaMA2-70B 58.4, Vicuna-7B 45.9, Vicuna-33B 51.7
Caveat
The counter-memory is LLM-generated and may not represent all forms of conflicting evidence; experiments use zero-shot setting.