Motivation and background#

The concept of agency and goal-directed behavior in large language models (LLMs) has been a topic of ongoing debate and investigation within the AI alignment community. While there are a diverse set of opinions on the subject, a challenge for researchers is that the internal processing of large language models is largely opaque, and in the case of recent models such as GPT-4 the training procedures themselves are also subject to a degree of secrecy. Therefore, objective assessment of the capabilities of large-language models cannot be conducted through inductive reasoning starting from first principles, but instead is a matter of empirical investigation, with experiments being the ultimate arbiter of what they can or can’t do, e.g. [Google, 2023].

Reinforcement learning (RL) has been widely studied as a method for training AI agents to learn goal-directed behavior. Though LLMs like GPT-3 are not directly trained using RL to adapt their responses in an online manner, recent studies suggest that they might acquire RL-like mechanisms through zero-shot learning, allowing them to perform downstream tasks such as solving n-armed bandit problems [Binz and Schulz, 2023]. This capacity for adaptation raises the possibility that LLMs could exhibit goal-like behaviors without explicit instruction.

Large-language models have been rapidly deployed into many real-world applications where they typically interact with and assist human users. Therefore, a key principle in assessing any emergent goal-like behaviour for these use-cases is to evaluate artificial agents in multi-agent tasks where outcomes depend not only on actions taken by artificial agents, but also their human counterparts. When evaluating incentives, the aspect of the outcome that is of interest is the expected utility obtained by each party, and the theoretical study of such tasks falls within the remit of game-theory, while the empirical study falls within the remit of experimental economics. Our research falls under the latter, and our goal is to systematically evaluate the propensity of large-language models to cooperate in a wide variety of multi-agent task environments with different experimental conditions.

Many scenarios discussed in the AI alignment debate focus on competitive zero-sum interactions. For example, a common analogy is competition for resources between different species occupying a particular niche; for example, [Tegmark, 2023] argues

We humans drove the West African Black Rhino extinct not because we were rhino-haters, but because we were smarter than them and had different goals for how to use their habitats and horns. In the same way, superintelligence with almost any open-ended goal would want to preserve itself and amass resources to accomplish that goal better.

In an AI safety context, the intuition behind such arguments is that AI systems have been to shown to outsmart humans in zero-sum games such as Chess and Go, and therefore if AI systems find themselves in situations in which they are competing with humans, the AI “species” will clearly out-compete inferior humans.

However, many interactions in both natural and artificial settings are characterized by non-zero-sum payoff structures [Phelps and Russell, 2015]. A famous example that was used to analyse existential risk of nuclear conflict during the cold war is the Prisoner’s Dilemma [Axelrod, 1997]. In an ecological context a related non-zero-sum game, the Hawk-Dove game, also known as the Chicken game, was introduced by [Maynard-Smith, 1973] as a way to analyse the outcomes of competition for resources among animals. In certain payoff structures, limited conflict can be an evolutionary equilibrium of this game when interactions are repeated within a large population. This game has been also applied to an analysis of existential risk in nuclear conflict; [Dixit et al., 2019] argue that the Cuban missile crisis can be analysed as a high-stakes dynamic chicken game in which neither the USSR nor the USA wanted to “blink” first.

Interestingly, in a one-shot version of the game, behaving irrationally by limiting one’s options can be a superior strategy. This is because in the absence of such limiting, attempts to manipulate the other player through brinkmanship are not credible threats. For example, in a game of Chicken where two opposing drivers are on a collision course and neither driver wants to be seen as the “chicken” by swerving, if we limit our choices by removing the steering wheel, and make this common knowledge, then the opposing driver’s best response is to swerve. Similar arguments were used during the cold war to remove rational deliberation from the decision whether to retaliate in the event of a preemptive strike by the enemy by “taking the human out of the loop” and putting systems on automated hair-trigger alert to make the threat of mutually assured destruction credible [Kahn, 1960]. Thus, in contrast to chess or Go, in non-zero-sum interactions, the most ruthless agents, or those with superior cognitive capacity, do not necessarily prevail.

Moreover, in both one-shot and iterated Prisoner’s Dilemma games with the number of rounds being common knowledge, the rational strategy is to defect, but experiments have shown that real people tend to cooperate, albeit conditionally. The fact that real people cooperate in these scenarios, despite the seemingly rational strategy to defect, highlights the importance of social norms in shaping human behavior [Fehr and Fischbacher, 2004]. Norms can facilitate cooperative outcomes by providing a shared understanding of acceptable behavior and allowing for the enforcement of rules through social sanctions.

In the context of AI alignment and non-zero-sum games, this underscores the importance of considering not only the cognitive capacity of AI agents but also their understanding and adherence to social norms. The ability of AI systems to adapt their behavior based on natural language prompts and to engage in reciprocal cooperation is crucial for creating AI agents that can better align with human values in complex, non-zero-sum settings.

By investigating the behavior of AI-generated agents in the iterated Prisoner’s Dilemma and other social dilemmas such as the ultimatum game we can contribute to a more comprehensive understanding of AI alignment in various interaction scenarios. This knowledge can, in turn, inform the development of AI systems that are better equipped to navigate the complexities of human cooperation and competition, while adhering to social norms and human values.

Researchers have argued that the prompt itself plays a crucial role in shaping the emergent behaviour from the model; for example, the default “helpful assistant” behavior of AI chatbots such as GPT-3 has been noted to differ from that of specific simulacra instantiated by user prompts (c.f. prompts used to “jail-break” GPT models) [0xk1g0, 2023, Janus, 2023]. More generally, LLMs can be arbitrarily scaffolded by injecting contextual information [Beren, 2023]. A particular use-case of a scaffolded LLM involves injecting information about a world-state, together with a persona that incorporates specific goals, which can be used to instantiate autonomous agents, either in the real-world [Richards, 2023], or in mult-agent simulations [Park et al., 2023].

From an AI alignment perspective, the fact that large language models can easily be scaffolded to deploy autonomous goal-oriented agents into production at very little cost highlights the need to systematically evaluate the conditions in which LLM-instantiated agents have a propensity or otherwise to cooperate in social dilemmas.

Given that the nature of an LLM agent depends on the persona and context introduced in the initial prompt, a key question is to what extent the level of cooperation elicited from the AI depends on features of the prompt. In particular, we are interested in whether large language models are capable of translating concepts such as altruism and selfishness, as expressed in natural language, into corresponding action policies in social dilemmas. This question is important, as the ability to operationalise these concepts in a variety of contexts would demonstrate the LLMs are capable of understanding and acting on cooperative norms that underpin human social behavior. This is the key research question investigated in our paper.