The complexity of perceptual processing in the brain shows the implausibility of the traditional
empiricist view that our sense experiences are copies of objects in the world. Without previously
acquired or inherited concepts, we would have a very difficult time dealing with the vast number of
sensory signals that our eyes, ears, and other sensors send to our brains. Perception requires brains to
be able to relate inputs from sensory organs with information they have already stored in the form of
synaptic connections between neurons. Ambiguous examples like the duck-rabbit show that
perception is not just the bottom-up processing of sensory inputs; it also involves top-down
interpretation based on what is already known. Because the brain is a parallel processor capable of
assessing many aspects simultaneously, we do not have to choose between hypotheses that perception
is primarily driven by input to sensory receptors or that it is primarily driven by top-down
interpretation. Rather, brains can perform inferences that simultaneously use both kinds of
information.