How the Brain ‘Constructs’ the Outside World

The “outside-in” model isn’t sufficient to explain how the brain processes stimuli.

Philosophers going back to Ancient Greece endorsed the tabula rasa concept to describe human cognition. This blank slate inside the skull is painted by experience. This concept persisted for millennia, even permeating neuroscience and psychology. This is why, for decades, neuroscience has labored under the misapprehension that cognitive processes originate with external inputs. These inputs are then sent to a “central processor” for interpretation.

While convenient and easy to explain in principle, this “outside-in” model has a serious flaw: No one knows where that processor resides, or exactly what it does with those inputs. It also assumes that neurons automatically turn simple patterns into complex ones and devise a meaning. But the central processor has eluded science. Was it free will? A homunculus? Executive function? Or just a “black box”? This approach cannot, for instance, explain how light falling on a flower brings to mind a memory of a summer day. The outside-in model can’t be the whole story.

The...