Sensation and perception psychology

Sensation is the body's detection of external or internal stimulation (e.g., eyes detecting light waves, ears detecting sound waves). Perception utilizes the brain to make sense of the stimulation (e.g., seeing a chair, hearing a guitar).

Sensation involves three steps:

For example, when touched by a soft feather, mechanoreceptors – which are sensory receptors in the skin – register that the skin has been touched. That sensory information is then turned into neural information through a process called transduction. Next, the neural information travels down neural pathways to the appropriate part of the brain, wherein the sensations are perceived as the touch of a feather.

Children are often taught five basic senses: seeing (i.e., vision), hearing (i.e., audition), tasting (i.e., gustation), smelling (i.e., olfaction), and touching. However, there are actually many more senses including vestibular sense, kinesthetic sense, sense of thirst, sense of hunger, and cutaneous sense to name a few.

Psychologists who specialize in psychophysics measure sensory sensitivity by identifying:

The wavelength, intensity and complexity of Light are detected by visual receptors in the retina of the eye. There are two types of visual receptors: rods and cones. Rods are sensitive to dim light, which makes them useful for seeing at night. Cones are more sensitive to color and bright light, which makes them more useful in daylight. Signals from rods and cones are transduced into useful neural information via the optic nerve. Blindness is the complete or nearly complete inability to see.

The frequency, intensity, and complexity of sounds waves in the external world are detected by auditory receptors (cilia or hair cell receptors) in the ear. Different patterns of cilia movement lead to different neural codes, which ultimately lead to hearing different loudness, pitch, and timbre of sounds. Deafness or hearing loss may occur in one or both ears.

Taste receptors (i.e., taste buds or papillae) are activated by the presence of food or another object on the tongue. Four basic tastes include sweet, salty, sour, and bitter. There is some debate on whether umami, or meatiness, is a fifth basic flavor. Aging is associated with loss of intensity in taste. Complete inability to taste is called ageusia.

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Wikipedia