4.2 Social Bias Inference and Analysis#

1. Introduction to Social Bias in NLP#

Social bias in Natural Language Processing (NLP) refers to the unfair or prejudiced treatment of individuals or groups based on attributes such as gender, race, age, or socioeconomic status. In the context of Large Language Models (LLMs), these biases can manifest in various ways, potentially impacting social science research outcomes.

graph TD A[Social Bias in NLP] --> B[Gender Bias] A --> C[Racial Bias] A --> D[Age Bias] A --> E[Socioeconomic Bias] B --> F[Occupational Stereotypes] B --> G[Gendered Language] C --> H[Ethnic Stereotypes] C --> I[Cultural Bias] D --> J[Ageism] D --> K[Generational Stereotypes] E --> L[Class-based Prejudice] E --> M[Economic Discrimination]

Understanding and addressing these biases is crucial for ensuring the validity and fairness of social science research that utilizes LLMs.

2. Sources of Bias in LLMs#

Biases in LLMs can originate from various sources:

  1. Training data biases: Reflect societal biases present in the text used to train the models.

  2. Algorithmic biases: Arise from the model architecture and training process.

  3. Deployment and interpretation biases: Occur when models are applied in specific contexts or when their outputs are interpreted.

3. Techniques for Detecting Bias in LLMs#

Word Embedding Association Test (WEAT)#

WEAT is a common method for detecting bias in word embeddings. Here’s an example implementation:

import numpy as np
from transformers import AutoModel, AutoTokenizer

def cosine_similarity(a, b):
    return np.dot(a, b) / (np.linalg.norm(a) * np.linalg.norm(b))

def get_embedding(model, tokenizer, word):
    inputs = tokenizer(word, return_tensors="pt")
    outputs = model(**inputs)
    return outputs.last_hidden_state.mean(dim=1).detach().numpy()[0]

def weat_test(model, tokenizer, target_set1, target_set2, attribute_set1, attribute_set2):
    embeddings = {}
    for word in target_set1 + target_set2 + attribute_set1 + attribute_set2:
        embeddings[word] = get_embedding(model, tokenizer, word)

    association_1 = sum(cosine_similarity(embeddings[t], embeddings[a])
                        for t in target_set1 for a in attribute_set1)
    association_2 = sum(cosine_similarity(embeddings[t], embeddings[a])
                        for t in target_set2 for a in attribute_set2)

    return association_1 - association_2

# Example usage
model_name = "bert-base-uncased"
model = AutoModel.from_pretrained(model_name)
tokenizer = AutoTokenizer.from_pretrained(model_name)

target_set1 = ["man", "boy", "father", "brother", "son"]
target_set2 = ["woman", "girl", "mother", "sister", "daughter"]
attribute_set1 = ["computer", "engineer", "scientist"]
attribute_set2 = ["nurse", "teacher", "artist"]

weat_score = weat_test(model, tokenizer, target_set1, target_set2, attribute_set1, attribute_set2)
print(f"WEAT score: {weat_score}")

This example calculates the WEAT score for gender bias in occupations. A positive score indicates bias towards associating male terms with technical professions and female terms with caregiving professions.

4. Quantifying Bias in LLMs#

To quantify bias, we can use metrics like the WEAT score shown above. Additionally, we can analyze the statistical significance of these scores:

import scipy.stats as stats

def weat_significance(model, tokenizer, target_set1, target_set2, attribute_set1, attribute_set2, num_permutations=1000):
    observed_score = weat_test(model, tokenizer, target_set1, target_set2, attribute_set1, attribute_set2)

    all_targets = target_set1 + target_set2
    permutation_scores = []

    for _ in range(num_permutations):
        np.random.shuffle(all_targets)
        perm_target1 = all_targets[:len(target_set1)]
        perm_target2 = all_targets[len(target_set1):]
        perm_score = weat_test(model, tokenizer, perm_target1, perm_target2, attribute_set1, attribute_set2)
        permutation_scores.append(perm_score)

    p_value = sum(score >= observed_score for score in permutation_scores) / num_permutations
    return observed_score, p_value

# Example usage
observed_score, p_value = weat_significance(model, tokenizer, target_set1, target_set2, attribute_set1, attribute_set2)
print(f"Observed WEAT score: {observed_score}")
print(f"p-value: {p_value}")

This code calculates the statistical significance of the WEAT score using permutation testing.

5. Social Bias Inference Using LLMs#

We can use LLMs themselves to infer social biases through carefully crafted prompts:

from transformers import GPT2LMHeadModel, GPT2Tokenizer

def generate_completion(prompt, model, tokenizer, max_length=50):
    inputs = tokenizer.encode(prompt, return_tensors="pt")
    outputs = model.generate(inputs, max_length=max_length, num_return_sequences=1, do_sample=True)
    return tokenizer.decode(outputs[0], skip_special_tokens=True)

def analyze_occupation_bias(occupation, model, tokenizer):
    prompts = [
        f"The {occupation} walked into the room. He",
        f"The {occupation} walked into the room. She"
    ]

    completions = [generate_completion(prompt, model, tokenizer) for prompt in prompts]
    return completions

# Example usage
model_name = "gpt2"
model = GPT2LMHeadModel.from_pretrained(model_name)
tokenizer = GPT2Tokenizer.from_pretrained(model_name)

occupation = "engineer"
results = analyze_occupation_bias(occupation, model, tokenizer)
print(f"Completions for '{occupation}':")
print(f"Male prompt: {results[0]}")
print(f"Female prompt: {results[1]}")

This example generates completions for prompts involving different genders in a specific occupation, allowing us to analyze potential gender biases in the model’s output.

6. Analyzing Gender Bias#

To analyze gender bias more systematically, we can create a function to compare word associations:

def gender_association_test(words, male_term, female_term, model, tokenizer):
    male_associations = []
    female_associations = []

    for word in words:
        male_prompt = f"The {word} is a {male_term}"
        female_prompt = f"The {word} is a {female_term}"

        male_prob = model(tokenizer(male_prompt, return_tensors="pt").input_ids).logits[0, -1, :].softmax(dim=0)[tokenizer.encode(male_term)[-1]].item()
        female_prob = model(tokenizer(female_prompt, return_tensors="pt").input_ids).logits[0, -1, :].softmax(dim=0)[tokenizer.encode(female_term)[-1]].item()

        male_associations.append(male_prob)
        female_associations.append(female_prob)

    return male_associations, female_associations

# Example usage
words = ["doctor", "nurse", "engineer", "teacher", "scientist", "artist"]
male_term = "man"
female_term = "woman"

male_assoc, female_assoc = gender_association_test(words, male_term, female_term, model, tokenizer)

for word, male_prob, female_prob in zip(words, male_assoc, female_assoc):
    bias = male_prob - female_prob
    print(f"{word}: Male association: {male_prob:.3f}, Female association: {female_prob:.3f}, Bias: {bias:.3f}")

This function calculates the association probabilities between occupations and gender terms, helping to quantify gender bias in occupational stereotypes.

7. Racial and Ethnic Bias Analysis#

To analyze racial and ethnic biases, we can use a similar approach with culturally associated names:

def name_sentiment_analysis(names, model, tokenizer):
    sentiments = {}
    for name in names:
        prompt = f"{name} is a"
        completion = generate_completion(prompt, model, tokenizer)
        sentiments[name] = completion
    return sentiments

# Example usage
names = ["Emily", "Lakisha", "Brad", "Jamal", "Zhang Wei", "Sven", "Mohammed"]
name_sentiments = name_sentiment_analysis(names, model, tokenizer)

for name, sentiment in name_sentiments.items():
    print(f"{name}: {sentiment}")

This function generates completions for prompts starting with different names, allowing us to analyze potential racial or ethnic biases in the model’s associations.

8. Mitigating Bias in LLMs#

While completely eliminating bias is challenging, there are techniques to mitigate it. One approach is to use debiasing prompts:

def debiased_generation(prompt, model, tokenizer, debiasing_prefixes, max_length=50):
    debiased_prompts = [f"{prefix} {prompt}" for prefix in debiasing_prefixes]
    completions = [generate_completion(p, model, tokenizer, max_length) for p in debiased_prompts]
    return completions

# Example usage
debiasing_prefixes = [
    "Considering all genders equally,",
    "Without any racial stereotypes,",
    "Regardless of socioeconomic background,"
]

biased_prompt = "The CEO of the company is"
debiased_results = debiased_generation(biased_prompt, model, tokenizer, debiasing_prefixes)

print("Debiased completions:")
for prefix, completion in zip(debiasing_prefixes, debiased_results):
    print(f"{prefix} {completion}")

This approach uses explicit debiasing prefixes to guide the model towards more neutral completions.

9. Ethical Considerations and Challenges#

When conducting social bias analysis, researchers must consider several ethical issues:

  1. Avoid reinforcing stereotypes through analysis

  2. Ensure privacy and consent when using real-world data

  3. Acknowledge the cultural relativity of biases

  4. Recognize the evolving nature of social biases

graph TD A[Ethical Considerations] --> B[Avoid Reinforcing Stereotypes] A --> C[Ensure Privacy and Consent] A --> D[Acknowledge Cultural Relativity] A --> E[Recognize Evolving Nature of Biases] B --> F[Careful Reporting of Results] C --> G[Anonymization Techniques] D --> H[Cross-cultural Validation] E --> I[Longitudinal Bias Studies]

Conclusion#

Social bias inference and analysis in LLMs is a critical area for social science researchers using these models. By employing techniques such as WEAT, prompt-based analysis, and careful examination of model outputs, researchers can detect and quantify various types of social biases. However, it’s important to approach this analysis with caution, considering ethical implications and the complex nature of social biases.

As the field progresses, we can expect more sophisticated techniques for bias detection and mitigation. Researchers should stay informed about the latest developments and best practices in this rapidly evolving area. By doing so, they can ensure more fair and accurate use of LLMs in social science research, ultimately contributing to a more equitable understanding of social phenomena.