Baysian perceptions

10/06/2009 by admin.

There is more from a podcast interview with Chris Frith (here). This time I quote his views on Baysian perception.

…Perception is a two-way process. This is why I talk about Reverend Thomas Bayes, who produced this formula two hundred years ago. What he’s essentially pointing out is that our perception of the world depends on two things: that is to say, the sensory information that’s coming in through our eyes and ears, and our prior expectations and our knowledge of the world. And it’s the balance of these two that creates what we experience.

His formula tells you how much do you have to change your model of the world given the new evidence that’s coming in. So if you have very strong expectations, that will affect what you actually perceive. In a sense you can’t perceive things that you don’t know something about already…

And also, people who study how the brain works suggest that the brain is a Baysian system that is concerned with making predictions, and collecting sensory evidence, and then looking at the prediction errors to decide what to do next. And certainly learning about the world these days is very much conceived in terms of a Baysian process where you predict what’s going to happen and then you adjust your learning on the basis of these prediction errors.

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