We take it for granted that we see the world as it actually is, but in fact, we do not. Our perception of the world is the brain’s best guess at what is actually happening, based on the information it receives through the senses. Optical illusions clearly demonstrate that the brain does not always interpret sensory information correctly, by producing a discrepancy between what we see and and how we perceive.
These discrepancies usually occur because the visual information is incomplete and the brain has to fill in the gaps. But our perceptions can be influenced by many factors, even under normal circumstances – we know, for example, that how we feel affects what we see, and that music affects how we perceive facial expressions.
A new study now shows that visual working memory can influence our perceptions, so that mental images in the mind’s eye can alter the way we see things.
Working memory refers to our ability to hold and manipulate limited amounts of information for a short period of time. This information is usually relevant to the task at hand – when making a phone call, for example, you might repeat the number to yourself several times until you have dialled it; once you’ve dialled the number, you stop the repetition and then quickly forget it. In exactly the same way, visual working memory allows us to retain visual information as mental images in the mind’s eye.