Read Incognito for Free Online

lines, but you cannot tell me
how many
without considerable effort. You can know some things abouta scene without knowing other aspects of it, and you become aware of what you’re missing only when you’re asked the question.
    What is the position of your tongue in your mouth? Once you are asked the question you can answer it—but presumably you were not aware of the answer until you asked yourself. The brain generally does not need to know most things; it merely knows how to go out and retrieve the data. It computes on a
need-to-know basis
. You do not continuously track the position of your tongue in consciousness, because that knowledge is useful only in rare circumstances.
    In fact, we are not conscious of much of anything until we ask ourselves about it. What does your left shoe feel like on your foot right now? What pitch is the hum of the air conditioner in the background? As we saw withchange blindness, we are unaware of most of what should be obvious to our senses; it is only after deploying our attentional resources onto small bits of the scene that we become aware of what we were missing. Before we engage our concentration, we are typically not aware that we are not aware of those details. So not only is our perception of the world a construction that does not accurately represent the outside, but we additionally have the false impression of a full, rich picture when in fact we see only what we need to know, and no more.
    The manner in which the brain interrogates the world to gather more details was investigated in 1967 by the Russian psychologistAlfred Yarbus. He measured the exact locations that people were looking at by using an eye tracker, and asked his subjects to gaze atIlya Repin’s painting
An Unexpected Visitor
(below). 11 The subjects’ task was simple: examine the painting. Or, in a different condition, surmise what the people in the painting had been doing just before the “unexpected visitor” came in. Or answer a question about how wealthy the people were. Or their ages. Or how long the unexpected visitor had been away.

     
    Six records of eye movements from the same subject. Each record lasted three minutes.
     

     
    1) Free examination. Before subsequent recordings, the subject was asked to: 2) estimate the material circumstances of the family;
     

     
    3) give the ages of the people; 4) surmise what the family had been doing before the arrival of the “unexpected visitor”;
     

     
    5) remember the clothes worn by the people; 6) estimate how long the “unexpected visitor” had been away from the family. From Yarbus, 1967.
     
    The results were remarkable. Depending on what was being asked, the eyes moved in totally different patterns, sampling the picture in a manner that was maximally informative for the question athand. When asked about the ages of the people, the eyes went to the faces. When asked about their wealth, the focus danced around the clothes and material possessions.
    Think about what this means: brains reach out into the world and actively
extract
the type of information they need. The brain does not need to see everything at once about
An Unexpected Visitor
, and it does not need to store everything internally; it only needs to know where to go to find the information. As your eyes interrogate the world, they are like agents on a mission, optimizing their strategy for the data. Even though they are “your” eyes, you have little idea what duty they’re on. Like a black ops mission, the eyes operate below the radar, too fast for your clunky consciousness to keep up with.
    For a powerful illustration of the limits ofintrospection, consider the eye movements you are making right now while reading this book. Your eyes are jumping from spot to spot. To appreciate how rapid, deliberate, and precise these eye movements are, just observe someone else while they read. Yet we have no awareness of this active examination of the page. Instead it seems as though ideas simply