Sensation and Perception Information in this presentation is taken from UCCP Content.

What is it? Sensation is simply the conscious experience associated with a stimuli. We have the utmost faith in our senses and that is crucial to our survival. Sensory stimulation provides us with basic data that we use to make hypotheses about the nature of the world. These hypotheses form our perceptions of the world. Sensation alone cannot explain our experiences as humans. We must also determine how well the world that our senses create actually corresponds to reality. Sensation is the process of detecting a physical stimulus, such as light, sound, heat, pressure or smell. Perception is the process of integrating, organizing and interpreting sensations.

Types of Processing There are many theories of how perception and pattern recognition operate. These theories can be categorized into two broad approaches: bottom-up processing and top-down processing. Perception involves both sensory information about the outside world and prior knowledge from the individual’s inner world. These two aspects are differently weighted by the two approaches to processing which are named to illustrate their emphases.

Types of Processing Bottom-up processing, also called data-driven processing, stresses the importance of the stimulus, and begins with the senses receiving information about the stimulus. This information starts the pattern-recognition process which combines information about the simple, basic features of the stimulus into a more complex, organized idea of the whole object. Top-down processing, also known as conceptually driven processing, stresses the role of an individual’s prior knowledge of concepts and organization of the environment in perceiving an object. Our experiences in the world have provided us with a set of expectations that help us recognize patterns quickly. That is, we expect certain objects to be found in certain locations, so this information will help us rapidly identify patterns in the environment.

Types of Processing It would be impossible for either of these approaches to processing alone to account for the complexities of perception. Rather, these two types of processing always work together. For example, when recognizing a face both processes work simultaneously. Because of top-down processing the shapes of different features (e.g. nose, mouth) are instantly recognizable partially because they are in a certain location on a face. Bottom-up processing is also at work as we combine the different features into our overall perception of the face. Thus the stimulus and the context are both very important contributors to perception.