NPTI

This repository is the official implementation of our paper "Neuron-based Personality Trait Induction in Large Language Models".

Dataset

To better identify personality-related neurons, we first constructed the PersonalityBench dataset, comprising 180,000 open-ended questions tailored to capture distinct personality traits based on Big Five personality theory. Specifically, we utilize the description from IPIP-NEO-300 questionnaire and common real-world topics introduced in UltraChat to generate the situational questions in PersonalityBench. The dataset is shown in NPTI/datset.

Personality-related Neurons Found by NPTI

Within a given layer, the FFN module can be expressed as:

$$h = \left( \sigma \left( \hat{h} W_1 \right) \odot \left(\hat{h} W_3 \right) \right)\cdot W_2,$$

where $\hat{\mathbf{h}}$ in $\mathbb{R}^{d}$ represents the output of the MHA module for a specific token in this layer. The function $\sigma(\cdot)$ typically denotes a non-linear activation function, such as SiLU. The learned projection matrices are $\mathbf{W}_1$ $\in$ $\mathbb{R}^{d \times d'}$, $\mathbf{W}_2$ $\in$ $\mathbb{R}^{d' \times d}$, and $\mathbf{W}_3$ $\in$ $\mathbb{R}^{d \times d'}$. In this context, a neuron is conceptualized as applying a linear transformation to a specific column of the weight matrix $\mathbf{W}_1$ followed by a non-linear activation function to the result. We identified neurons related to the positive or negative aspects of each personality trait. The neurons are listed in the NPTI/neuron_results directory. Each neuron is represented as a tuple, where each element corresponds to the following in order: (layer number, neuron index, absolute value of activation probability difference, activation probability, 95th percentile value).

Identifying Language-specific Neurons

To find personality-related neurons in LLaMA-8B-Instruct, you can excute:

bash NPTI/code/search_neuron.sh

Using NPTI to modify the personality of LLM

To modify certain personality trait of LLM using NPTI, you can excute:

bash NPTI/code/answer_question_change_neuron.sh

Using ChatGPT to score the results:

To use ChatGPT to automatically assess the degree of expression of a specific personality trait and the fluency of each response, you can excute:

python NPTI/code/gpt4_score.py