Uniquely human intelligence arose from expanded information capacity - Nature Reviews Psychology

🌈 Abstract

The article discusses theories of how human cognition is unique, arguing that the evidence supporting domain-specific theories is confounded by general information-processing differences. It proposes that human uniqueness arises through genetic quantitative increases in global information processing capacity, which explains differences across cognitive domains, behavioral comparisons between species, and child development phenomena.

🙋 Q&A

[01] Theories of Human Uniqueness

1. What are the main types of theories proposed to explain human uniqueness? The article discusses two main types of theories:

• Domain-specific theories that propose a single, specific adaptation or 'instinct' as the central catalyst of human-like thought (e.g. social reasoning, hierarchical syntax).
• Alternatives that propose more general learning adaptations, such as the cultural intelligence hypothesis, which suggests humans are unique due to their social learning ability and accumulation of cultural knowledge.

2. What are the key challenges faced by domain-specific theories? The article outlines three key challenges:

1. The key behaviors that set humans apart must be acquired, and the specific representations possessed seem unconstrained.
2. The uniquely human domains are diverse, and a single adaptation is unlikely to account for all of them.
3. Different domain-specific theories propose different adaptations as the 'silver bullet', contradicting each other.

3. How do cultural intelligence theories differ from domain-specific theories? Cultural intelligence theories emphasize evolutionary expansions in general cognitive mechanisms like learning, memory, and executive function as the foundation for human innovation, complex communication, and flexibility. They propose that general cognitive processes, rather than domain-specific adaptations, are the key to human uniqueness.

[02] Information Capacity Theory

1. What is the core proposal of the information capacity theory? The information capacity theory proposes that human uniqueness largely results from a global adaptation for increased information processing capacity, which alters human cognition profoundly and qualitatively. This quantitative change in information processing capacity is argued to be sufficient to account for the diverse range of uniquely human cognitive abilities.

2. What are the three key predictions of the information capacity theory?

1. Non-human primates will show some degree of success on tasks previously thought to require domain-specific human adaptations.
2. There will be continuous, quantifiable advantages for humans relative to non-human species on basic cognitive tasks.
3. small increases in information capacity can yield qualitative changes in behavior in humans, non-human animals, and computational systems.

3. How does the information capacity theory differ from other domain-general theories? The information capacity theory is a strict continuity theory, proposing that quantitative changes in global information processing capacity, rather than qualitative changes in domain-specific mechanisms, are the key to human uniqueness. It builds on but expands upon ideas from the cultural intelligence hypothesis by providing a cognitive explanation for how quantitative changes in capacity can lead to the emergence of diverse new cognitive abilities.

[03] Evidence for Information Capacity Theory

1. What evidence is provided for continuity of ability across species? The article reviews evidence showing that non-human primates exhibit some degree of success on tasks related to social reasoning, relational reasoning, causal reasoning and tool use, and symbolic thought and language. The differences are often quantitative rather than qualitative, with non-human primates showing more limited capacities compared to humans.

2. What evidence is provided for differences in capacity limitations across species? The article reviews literature demonstrating systematic performance gaps between humans and other species on basic cognitive tasks involving simple learning rates, memory capacity, cognitive control, and sequence learning and memory. These domain-general differences in information processing capacity are argued to underlie the qualitative differences in cognition between humans and other species.

3. How does the article demonstrate that quantitative changes in capacity can yield qualitative changes in behavior? The article discusses how developmental changes in children's information processing capacity are linked to qualitative conceptual changes, such as the emergence of theory of mind. It also reviews computational evidence showing how small changes in memory capacity can lead to dramatic differences in the types of computations a system can perform.

[04] Conclusion

1. What is the key proposal of the information capacity theory regarding the evolution of human uniqueness? The information capacity theory proposes that uniquely human cognitive abilities arise from a global, genetic adaptation for increased information processing capacity, rather than from domain-specific evolutionary changes. This quantitative change in capacity is argued to be sufficient to account for the diverse range of qualitative differences between human and non-human cognition.

2. How does the information capacity theory relate to prior theories of human uniqueness? The information capacity theory is synergistic with versions of the cultural intelligence hypothesis that emphasize the role of expansions in general learning and memory capacities. However, it goes beyond prior theories by providing a cognitive explanation for how quantitative changes in capacity can lead to the emergence of new, qualitatively distinct cognitive abilities.

3. What are the key implications of the information capacity theory for understanding the evolution and development of human intelligence? The theory suggests that differences in degree (information capacity) can yield differences in kind (qualitative cognitive abilities) both across species and during human development. It highlights how expansions in general information processing capacity, rather than domain-specific adaptations, were likely a key driver of the unique features of human cognition that emerged through cultural evolution.