SENSATION AND PERCEPTION

Sensation and perception let us to understand each other and the world around us.

Sensation: is the activation of the sense organs by a source of physical energy. Perception is described as the sorting out, interpretation, analysis, and integration of stimuli by the sense organs and brain.

Each sense organ is activated by different types of stimuli. Stimulus is called energy that produces a response in sense organ.

Light stimuli activate eyes, smell stimuli – smell and so on, so because of sense organs’ ability react to different type of stimuli, we can differentiate one stimulus from others. More over stimuli can be differed in intensity, relating how strong a stimulus needs to be before it can be detected. In stimulus type and intensity is interested psychophysics, this is study of the relationship between the physical aspects of stimuli and our psychological experience of them.

Each person is differently sensitive for the same stimulus. This level of sensitive is described as absolute threshold – the smallest intensity of a stimulus that must be present for the stimulus to be detected.

Talking about vision, main thing to know is that, there are receptors called rods and cones. Cones are responsible for color perception. There are 3 kinds of cones in the retina, each of which responds primarily to a specific range of wavelengths. That’s mean there are 3 main colors: red, blue and green. This is trichromatic theory of color vision.

People can hear different frequency of sounds. Sound- is the movement of air molecules brought about by a source of vibration.

There are 2 theories of hearing: Place (low-frequency sounds) and Frequency (high-frequency sounds). Higher frequency of sounds can hear just some animals, but not us.

Other two senses smell and taste are closely related. Human sense of smell permits us to detect more than 10.000 separate smells. Also we have good memory for smells. What about sense of taste so it involves receptor cells that respond to four basic stimulus qualities: sweet, sour, salty and bitter. There is fifth sense of taste called umami. According to how we recognize what kind of taste is it, there are 2 theories, one says that each part of tongue can detect different taste; it just depends on which area of tongue is stimulating. Another one claims that 4 different taste receptors cells are situated on the all tongue, just in one area one kind of cells are situated bushier than in others.

All our skin senses – touch, pressure, temperature, and pain, play a critical role in survival, making us aware of potential danger to our bodies. Each our bodies’ area is differently sensitive to stimuli. For example, fingertips have many more receptors cells sensitive to touch and are more sensitive than other areas of the body. In addition, most sensitive skin’s receptors are pain receptor cells. Gate-control theory of pain claims that particular nerve receptor in the spinal cord lead to specific areas of the brain related to pain.

                                                             

Gestalt laws of organization

Some of the most basic perceptual processes can be described by a series of principles that focus on the ways we organize bits and pieces of information into meaningful wholes. According to gestalt laws of organization - information processing is dived into top-down or bottom-up processing.

First one is perception that is guided by higher-level knowledge, experience, expectations, and motivations. Bottom-up processing is described as perception that consists of the progression of recognizing and processing information from individual components of a stimuli and moving to the perception of the whole. But perceiving and processing information sometimes can befall mistakes of perception, such as visual illusion: physical stimuli that consistently produce errors in perception. An example of illusion could be railroad tracks that seem to join together in the distance

All things considered, studying perception and sensation system in this chapter we have seen how external stimuli evoke sensory responses and how our different senses process the information contained in those responses. Also, these systems play very important role in our life: help us to adapt, to understand environment and to survive.