Sensation and perception

Definitions Sensation The detection of physical energy emitted or reflected by physical objects. Occurs when energy in the external environment or the body stimulates receptors in the sense organs. Perception The process by which the brain organizes and interprets sensory information.

Our Senses Vision Hearing Taste Smell Touch

Specific nerve energies Different sensory modalities exist because signals received by the sense organs stimulate different nerve pathways leading to different areas of the brain. Synesthesia A condition in which stimulation of one sense also evokes another.

Absolute threshold The smallest quantity of physical energy that can be reliably detected Vision A single candle flame from 30 miles on a clear night Hearing The tick of a watch from 20 feet in total quiet Smell One drop of perfume in a 6-room apartment Touch The wing of a bee on the cheek, dropped from 1 cm Taste One teaspoon of sugar in 2 gallons of water

Difference threshold The smallest difference in stimulation that can be reliably detected by an observer when two stimuli are compared. Also called the Just Noticeable Difference (JND).

Sensory adaptation and deprivation Adaptation The reduction or disappearance of sensory responsiveness when stimulation is unchanging or repetitious. Prevents us from having to respond continuously to unimportant information. Deprivation The absence of normal levels of sensory stimulation.

Sensory overload Over-stimulation of the senses. Can use selective attention to reduce sensory overload. Selective attention: the focusing of attention on selected aspects of the environment and the blocking out of others.

What we see Hue Visual experience specified by color names and related to the wavelength of light. Brightness Visual experience related to the amount of light emitted from or reflected by an object. Saturation Visual experience related to the complexity of light waves.

Trichromatic theory Young (1802) and von Helmholtz (1852) both proposed that the eye detects 3 primary colors. Red, blue, and green All other colors derived by combination.

Ambiguous Figure Also known as ambiguous illusions are pictures or objects that elicit a perceptual 'switch' between the alternative interpretations. –The brain can interpret the ambiguous cues in two different ways.

Distorting Illusions Characterized by distortions of size, length, or curvature.

Visual constancies The accurate perception of objects as stable or unchanged despite changes in the sensory patterns they produce

Color in context The way you perceive a color depends on the color surrounds.

What we Hear Loudness The dimension of auditory experience related to the intensity of a pressure wave. Pitch The dimension of auditory experience related to the frequency of a pressure wave. Timbre The dimension of auditory experience related to the complexity of a pressure wave.

What we Taste Five basic tastes Salty, sour, bitter, sweet, and umami Umami is one of the five basic tastes sensed by specialized receptor cells present on the human Umami is a Japanese word meaning savory, a "deliciousness" factor deriving specifically from detection of the natural amino acid, glutamic acid, or glutamates common in meats, cheese, broth, and other protein-heavy foods. Glutamate appears in foods and food ingredients such as –soy sauce –fish sauce –parmesan –anchovies –monosodium glutamate (MSG)

Different people have different tastes based on Genetics Culture Learning Food attractiveness

What we Smell Airborne chemical molecules enter the nose and circulate through the nasal cavity. Vapors can also enter through the mouth and pass into nasal cavity. Receptors on the roof of the nasal cavity detect these molecules.

Somatosensory System Widespread and diverse sensory system –touch –temperature –pain –kinesthesia (body position and movement) –equilibrioception (balance)