Types of perception: can be bottom up processing: involves taking individuals top down process: is where sensory info is interpreted in terms of existing knowledge, concepts, ideas or expectations. Attentions refers to processes of focusing on one stimuli while ignoring the rest attention bias: when a person fails to notice an unexpected stimuli in plain sight. Change blindness: is a perceptual phenomenon that occurs when a change in visual stimulus is introduced and the observer does not notice it. Holistic processing: gestalt psychology: suggests that the whole is often more than foreground relations. Suggests that the foreground figure is usually on top of the background. Proposed 4 gestalt laws: 1) the law of similarity. Constancies: regardless in actual sensation changes, we can still perceive stimuli as itself: size, brightness, direction, other constancies (taste, song) Image on retina is 2dbut we live in a 3d world.