On Intelligence: How a New Understanding of the Brain Will Lead to the Creation of Truly Intelligent Machines

by Jeff Hawkins

intelligence is not just a matter of acting or behaving intelligently. Behavior is a manifestation of intelligence, but not the central characteristic or primary definition of being intelligent. A moment’s reflection proves this: You can be intelligent just lying in the dark, thinking and understanding. Ignoring what goes on in your head and focusing instead on behavior has been a large impediment to understanding intelligence and building intelligent machines.

there are four attributes of neocortical memory that are fundamentally different from computer memory: • The neocortex stores sequences of patterns. • The neocortex recalls patterns auto-associatively. • The neocortex stores patterns in an invariant form. • The neocortex stores patterns in a hierarchy.

Memories are stored in a form that captures the essence of relationships, not the details of the moment. When you see, feel, or hear something, the cortex takes the detailed, highly specific input and converts it to an invariant form. It is the invariant form that is stored in memory, and it is the invariant form of each new input pattern that it gets compared to. Memory storage, memory recall, and memory recognition occur at the level of invariant forms. There is no equivalent concept in computers.

The three properties of cortical memory discussed in this chapter (storing sequences, auto-associative recall, and invariant representations) are necessary ingredients to predict the future based on memories of the past.

the cortex evolved primarily to provide a memory of the world. An animal with a large cortex could perceive the world much as you and I do. But humans are unique in the dominant, advanced role the cortex plays in our behavior. It is why we have complex language and intricate tools whereas other animals don’t. It is why we can write novels, surf the Internet, send probes to Mars, and build cruise ships.

With humans the cortex has taken over most of our motor behavior. Instead of just making predictions based on the behavior of the old brain, the human neocortex directs behavior to satisfy its predictions.

Your cortex creates a model of the world in its hierarchical memory. Thoughts are what occur when this model runs on its own; memory recall leads to predictions, which act like sensory inputs, which lead to new memory recall, and so on. Our most contemplative thoughts are not driven by or even connected to the real world; they are purely a creation of our model. We close our eyes and seek quiet so that our thinking will not be interrupted by sensory input.

To the cortex, our bodies are just part of the external world. Remember, the brain is in a quiet and dark box. It knows about the world only via the patterns on the sensory nerve fibers. From the brain’s perspective as a pattern device, it doesn’t know about your body any differently than it knows about the rest of the world. There isn’t a special distinction between where the body ends and the rest of the world begins. But the cortex has no ability to model the brain itself because there are no senses in the brain. Thus we can see why our thoughts appear independent of our bodies, why it feels like we have an independent mind or soul. The cortex builds a model of your body but it can’t build a model of the brain itself. Your thoughts, which are located in the brain, are physically separate from the body and the rest of the world. Mind is independent of body, but not of brain.