# Perceptual Set
Our perception is defined by what cognitive psychologists call a “perceptual set".
Perceptual set is a tendency to perceive or notice some aspects of the available sensory data and ignore others.
Perceptual set works in two ways:
- The perceiver has certain expectations and focuses attention on particular aspects of the sensory data
- The perceiver knows how to classify, understand and name selected data and what inferences to draw from it
## References
- [Perceptual Set](http://www.simplypsychology.org/perceptual-set.html), by Saul McLeod