Our perception of an object (or a situation) depends upon our knowledge of that object (or that situation) and how it relates to our experiences.
There were two schools of thought regarding the roles of the brain vs. the heart in defining human nature. Plato believed that the rational part of our soul resided in the brain, while the courageous nature of humans was dictated by the heart. Aristotle believed that it was the heart that controlled all our feelings, thought processes and actions. This sounds silly to us now, but thousands of years ago, the only information available about physiology was that which was readily perceived by direct observation. Imagine presenting someone who had no knowledge of insects with a green, hairy caterpillar. The person would be able to describe its physical characteristics, perhaps have an emotional reaction to it only because he has experience with the color green, with hair, and with the emotions that creepy crawling things elicit. Since he knows nothing about the life cycle of caterpillars, his knowledge is limited to what is directly observable. However, someone familiar with caterpillars would see beyond the directly observable and would wonder what kind of moth or butterfly it would become.