Haneen Mansoor — Updated On June 13th, 2023
Artificial Intelligence Machine Learning Python Reinforcement Learning Reinforcement Learning from Human Feedback


As artificial intelligence (AI) continues to advance, it is becoming increasingly important to develop methods that ensure AI systems align with human values and preferences. Reinforcement Learning from Human Feedback (RLHF) is a promising strategy for achieving this alignment. It allows AI systems to learn from human supervision. This article will provide an overview of RLHF and its implementation using the OpenAI Gym environment. We will also delve into ethical considerations designers must make while creating RLHF systems.

By this article’s end, readers will understand how to apply RLHF in solving complex problems using the OpenAI Gym environment.

Also Read: How Does ChatGPT Work: From Pretraining to RLHF

Learning Objectives

With the help of this article, you will be able to learn about-

  1. Understand the Reinforcement Learning from Human Feedback (RLHF) concept and its significance in training AI systems.
  2. Explore the implementation of RLHF using the OpenAI Gym environment, a popular framework for developing and comparing reinforcement learning algorithms.
  3. Recognize the importance of AI alignment and the ethical considerations in designing RLHF systems aligning with human values and objectives.
  4. Gain familiarity with real-world applications of RLHF in domains such as robotics, gaming, healthcare, and finance, highlighting its effectiveness in improving AI system performance.
  5. Explore alternative approaches to RLHF, including Inverse Reinforcement Learning, Preference-based Reinforcement Learning, and Multi-objective Reinforcement Learning, and understand their advantages and limitations compared to RLHF.

This article was published as a part of the Data Science Blogathon.

To start, let’s introduce some essential terms that will be discussed throughout the article.

Reinforcement Learning from Human Feedback (RLHF)

Machine learning techniques like reinforcement learning teach an agent to interact with the environment in a way that maximizes a reward signal.

  • The environment provides the reward signal in many instances, such as in games or robotics assignments. However, in other circumstances, establishing a reward signal could be challenging or expensive, or the task might be too harsh for an agent to figure out independently.
  • The problem is addressed by reinforcement learning from human feedback (RLHF), which incorporates expert human feedback into the learning process. The agent can be led to perform better by using this feedback. This may come in the form of evaluations or demonstrations.

AI Alignment

  • AI alignment ensures that designers and developers design and develop AI systems to align with human values and objectives.
  • As AI systems become more advanced and autonomous, it is essential to ensure that they act in a way that benefits society and avoids unintended consequences.
  • AI alignment involves developing algorithms, frameworks, and policies to guide AI systems toward goals aligned with human values while considering the risks and uncertainties associated with AI development.
  • AI alignment aims to build AI systems that society can trust to act in humanity’s best interests, ensuring their safe and ethical deployment across various domains.
OpenAI Gym | AI

The OpenAI Gym Environment

The OpenAI Gym is a popular framework for developing and comparing reinforcement learning algorithms. RLHF offers various environments, including classic control tasks, Atari games, and robotics simulations that users can employ for RLHF.

  • Each environment defines a specific task or problem with which an agent can interact and provides a set of observations, actions, and rewards that the agent can use to learn.
  • Some popular environments in the Gym include CartPole, MountainCar, and LunarLander, which all pose different challenges for reinforcement learning agents.
  • One such environment is the CartPole-v1 environment. It involves balancing a pole on a cart by moving the cart left or right.
  • The goal is to keep the pole balanced for as long as possible, with a reward of 1 for each time step that the bar remains balanced.
  • The episode ends if the pole is more than 15 degrees vertical or the cart moves more than 2.4 units from the center.
  • The CartPole-v1 environment is a good choice for RLHF. This is because it is simple and easy to understand yet still poses a challenging problem for the agent to solve.

By understanding these critical terms, we can delve into the details of RLHF and its implementation in the OpenAI Gym environment.

OpenAI Gym Environment | AI

Implementation of RLHF in Python using OpenAI Gym

To implement RLHF in Python, we can use the OpenAI Gym environment and the TensorFlow machine learning framework.

  • Import the required libraries:
# Import the libraries
import gym
import numpy as np
import tensorflow as tf
  • Define the RLHFAgent class, which will contain the methods for building the neural network model, generating actions using the current policy, and updating the approach based on human feedback.
# Define the RLHF agent class
class RLHFAgent:
    def __init__(self, env):
        self.env = env
        self.obs_dim = env.observation_space.shape[0]
        self.act_dim = env.action_space.n
        self.model = self.build_model()

Also Read: A Basic Introduction to Tensorflow in Deep Learning

In the RLHFAgent class, we first initialize the agent by specifying the OpenAI Gym environment and the dimensions of the observation and action spaces.

  • Build the neural network model, which will be used to generate actions based on the current policy.
# Build the neural network model
def build_model(self):
    model = tf.keras.Sequential([
        tf.keras.layers.Dense(64, activation='relu', input_shape=(self.obs_dim,)),
        tf.keras.layers.Dense(64, activation='relu'),
        tf.keras.layers.Dense(self.act_dim, activation='softmax')
    return model
  • Define the generate_action method, which will use the current policy to generate an action based on the recent observation.
# Define the generate_action method
def generate_action(self, obs):
    obs = np.reshape(obs, [1, self.obs_dim])
    action_probs = self.model.predict(obs)[0]
    action = np.random.choice(self.act_dim, p=action_probs)
    return action
  • Define the update_policy method, which will update the policy based on human feedback.
# Define the update_policy method
def update_policy(self, obs, action, feedback):
    obs = np.reshape(obs, [1, self.obs_dim])
    action_probs = self.model.predict(obs)[0]
    action_mask = np.zeros(self.act_dim)
    action_mask[action] = 1
    feedback = np.array([feedback])
    loss = self.model.train_on_batch(obs, feedback * (action_mask - action_probs))
  • Define the run_episode method, which will run a single episode of the environment using the current policy and gather human feedback.
# Define the run_episode method
def run_episode(self):
    obs = self.env.reset()
    done = False
    total_reward = 0
    while not done:
        action = self.generate_action(obs)
        obs, reward, done, info = self.env.step(action)
        feedback = int(input('Was the action correct? (0/1)'))
        self.update_policy(obs, action, feedback)
        total_reward += reward
    return total_reward
  • Finally, we can create an instance of the RLHFAgent class and run the CartPole-v1 environment to gather human feedback and improve the policy.
# Create an instance of the RLHF agent
env = gym.make('CartPole-v1')
agent = RLHFAgent(env)

# Run the environment and gather human feedback
for i in range(10):
    total_reward = agent.run_episode()
    print('Episode {}: Total Reward = {}'.format(i+1, total_reward))

Real-World Examples of Applications of RLHF

Some real-world examples of how RLHF has been successfully applied in various domains:

1. Robotics:

  • Google DeepMind applied RLHF to train a robot to grasp objects in a cluttered environment. They used human feedback to guide the robot’s exploration, and it achieved human-like performance in object grasping.

Also Read: DeepMind CEO Says AGI May Be Possible Very Soon

  • MIT researchers applied RLHF to train a robotic arm to assist with cooking tasks. They used human feedback to guide the robot’s actions, and the robot learned to help with tasks such as pouring and stirring.

2. Gaming:

  • OpenAI used RLHF to train an AI agent to play Dota 2. They used feedback from professional human players to improve the agent’s performance. The AI agent beat top professional players in the game, demonstrating the effectiveness of RLHF in complex domains.

Also Read: How AI Is Revolutionizing Game Testing in 2023

3. Healthcare:

  • Researchers from the University of California, San Francisco, used RLHF to personalize radiation therapy for cancer patients. They used human feedback to guide the selection of radiation doses and achieved better outcomes than traditional treatment planning methods.

Also Read: Machine Learning & AI for Healthcare in 2023

4. Finance:

  • Researchers from the University of Oxford used RLHF to optimize investment portfolios. They used human feedback to adjust the agent’s investment strategies and achieved better returns than traditional methods.

Also Read: Applications of Machine Learning and AI in Banking and Finance in 2023

These examples demonstrate the effectiveness of RLHF in a wide range of domains, from robotics to finance. By using human feedback, RLHF can improve the performance of AI systems and ensure that they align with human values.

Ethical Considerations to RLHF

RLHF has the potential to be a powerful tool for creating AI systems that are safe and dependable while also being in line with human values and preferences. However, one should also be conscious of ethical issues.

  • If the human input lacks variation or representation, one concern is that RLHF might be employed to reinforce preexisting biases or preconceptions.
  • When individuals use RLHF to automate operations that should not be automated, it can potentially lead to adverse or harmful effects, particularly in industries such as banking or healthcare.

Therefore, the following measures can be considered:

  • Thoroughly evaluate the use cases and potential repercussions of RLHF and include various experts and stakeholders in designing and deploying RLHF systems to alleviate these worries.
  • We must collect human feedback ethically, responsibly, with informed consent, and with the appropriate privacy measures.
  • In addition to allowing participants to opt out or withdraw their comments at any moment, this entails clearly defining the goal and use of the feedback.
  • Additionally, it’s critical to regularly monitor and assess RLHF systems to check for any biases or unintended consequences that might appear.
  • Regular testing and auditing can assist in finding and resolving any flaws before they cause serious harm.

Overall, even though RLHF has the potential to be a valuable tool for creating AI systems that are more ethical and harmonious, it is crucial to approach its research and deployment with prudence and attention.

Alternative Approaches to RLHF

While RLHF is a promising strategy, several alternative approaches to aligning AI systems with human values exist. Some popular methods include Inverse Reinforcement Learning, Preference-based Reinforcement Learning, and Multi-objective Reinforcement Learning.

1. Inverse Reinforcement Learning (IRL)

  • Infers the preferences of an expert by observing their behavior rather than explicitly asking for feedback
  • Recovers a reward function that explains the expert’s observed behavior
  • Trains a reinforcement learning agent that mimics the expert’s behavior using the inferred reward function
  • Advantages: learns from implicit feedback, helpful when explicit feedback is not available
  • Limitations: requires a good model of the expert’s behavior, which can be difficult to obtain

2. Preference-based Reinforcement Learning (PBRL)

  • Agent generates a set of trajectories, and the human evaluates these trajectories and provides feedback in the form of pairwise comparisons
  • Learns a policy that maximizes the human preferences
  • Useful when the human’s choices are complex and difficult to express in the form of a reward function
  • Advantages: can handle complicated preferences, can learn from explicit feedback
  • Limitations: can be time-consuming, may require a large amount of input from the human

3. Multi-objective Reinforcement Learning (MORL)

  • Agent optimizes multiple objectives simultaneously by assigning different weights to them.
  • One can learn weights from human feedback or define them based on prior knowledge.
  • Useful when the agent needs to balance different trade-offs
  • Advantages: can optimize multiple objectives, applicable when balancing trade-offs
  • Limitations: can be challenging to implement, may require a large number of parameters to be tuned

Each approach has its strengths and weaknesses. The choice of method will depend on the specific problem and available resources.


The article summarizes the key points covered, namely:

  1. RLHF involves using a combination of reinforcement learning and human feedback to improve the performance of an AI agent.
  2. RLHF can be implemented using a simple modification of the REINFORCE algorithm. It updates the policy based on feedback provided by a human expert.
  3. The potential of RLHF to build AI systems aligned with human values and preferences while ensuring safety and reliability is significant.
  4. There are ethical considerations to be aware of when using RLHF. Reinforcing biases or prejudices and automating tasks that should not be automated pose risks.
  5. To address these concerns, it is essential to consider the use cases and potential consequences of RLHF carefully. One should also involve diverse experts and stakeholders in designing and deploying RLHF systems.
  6. The alternative approaches to aligning AI systems with human values include Inverse Reinforcement Learning, Preference-based Reinforcement Learning, and Multi-objective Reinforcement Learning.

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Frequently Asked Questions

Q1. What does RLHF stand for?

A. RLHF stands for Reinforcement Learning from Human Feedback.

Q2. What is the function of RLHF?

A. The function of RLHF is to train machine learning models through a combination of reinforcement learning and human feedback. It involves using human-generated data to provide reward signals to the model, allowing it to improve its performance iteratively.

Q3. What is RLHF in language models?

A. In language models, RLHF refers to the application of reinforcement learning from human feedback. It helps improve the model’s output by incorporating human feedback, enabling it to generate more accurate and contextually relevant text.

Q4. What are the alternatives to RLHF?

A. Alternatives to RLHF include supervised learning, unsupervised learning, and self-supervised learning. Each approach has its own advantages and is suitable for different scenarios. RLHF stands out when human-generated feedback is valuable in training models to achieve better performance in specific tasks.

Q5. Why is RLHF better than supervised?

A. RLHF offers advantages over supervised learning, allowing the model to learn from a wider range of human-generated data. It enables the model to explore different possibilities and make adjustments based on feedback, leading to improved performance in complex tasks where supervised approaches may fall short.

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