Chapter 3 Slides.pptx

Sensation and Perception Chapter 3 Sensation and Perception • Sensation - The process of ­ receiving stimulus energies from the external environment and transforming those energies into ­neural energy. • Perception - The process of organizing and interpreting sensory information so that it makes s...

Sensation and Perception Chapter 3 Sensation and Perception • Sensation - The process of ­ receiving stimulus energies from the external environment and transforming those energies into ­neural energy. • Perception - The process of organizing and interpreting sensory information so that it makes sense. Sense Organs Eyes Ears Nose Skin Tongu e Sensations and The Brain • Sensory receptors recognize the information and sends it to the correct nerve and brain area. Classes of Sensory Transmitted Information • Photoreception: detection of light, perceived as sight • Mechanoreception: detection of pressure, vibration, and movement, perceived as touch, hearing, and equilibrium (or balance) • Chemoreception: detection of chemical stimuli, perceived as smell and taste Visual System • Light travels through wavelengths • Steps • Light enters the eye • Passes through the cornea, anterior chamber, lens, and vitreous • Finally reaches the photoreceptor cells of the retina Visual Systems • Retina - records electromagnetic energy and converts it to neural impulses for processing in the brain • Rods - sensitive to light but not very useful for color vision. • Cones - allow for color perception • Optic nerve - Carries visual information to the brain for further processing. Visual Processing Color Theories • Young-Hemholtz • Trichromatic Theory • The retinas contain three types of cone cells, each responding best to a particular wavelength of light 1. Short wavelengths (blue light) 2. Medium wavelengths (green light) 3. Long wavelengths (red light). • “Other colors” are perceived through the mixing of signals from the cones. Color Theories Cont. • Opponent process theory • Two-color processes: • one for red versus green • one for yellow versus blue perception • In the thalamus, some neurons are turned on by red but off by green, for example, which helps explain afterimages. • The negative color after-image of the U.S. flag is a great demonstration of this. Color Theories Cont. • How we perceive color is informed by types of color blindness. • Monochromatic color blindness - the person cannot see any color at all. • Dichromatic color blindness - the person perceives only two of the three visual pigments. Problems with Vision • Cataracts: clouding of the lens of the eye; affects acuity and color vision • Retinopathy: damage to the small blood vessels; begins to leak and may cause blurred vision, blind spots, or floaters • Glaucoma: fluid pressure builds up inside the eye, damaging the optic nerve; blurred vision and loss of peripheral vision Problems with Vision • Macular degeneration: inability to see objects clearly; distorted vision and dark spots in the center of vision • Hyperopia (farsightedness): focusing the image behind the retina; difficulty in seeing objects close up • Myopia (nearsightedness): focusing the image in front of the retina; difficulty in seeing objects far away Auditory System It all starts with a sound! • Sound - a mechanical energy typically caused by vibrating objects. • Vibrations produce movement of air molecules (sound waves). • Moving one’s head helps in detecting the source of a sound. Structures of the Ear Structures of the Ear • Pinna: external (visible) flap of skin and cartilage • Auditory canal: part of outer ear along with pinna, leads to tympanic membrane • Tympanic membrane: also called eardrum, separates outer ear from middle ear and vibrates with reception of sound content outline • Ossicles: three bones in middle ear (malleus/incus/stapes or hammer/anvil/stirrup) set in motion by ear drum that transmit sound vibrations to the cochlea • Cochlea: a part of the inner ear, contains fluid and receptors Auditory Theories 1. Place theory: Differences in pitch result from stimulation of different areas of the basilar membrane. 2. Frequency theory: Differences in pitch are due to rate of neural impulses traveling up the auditory nerve. Taste (Gustation) • Taste cells are chemical-sensitive receptors located in taste bud clusters. • Five Basic Qualities: • • • • • Sweetness Saltiness Sourness Bitterness Umami - glutamates Smell (Olfaction) • Receptors for smell are located on the olfactory epithelium, a thin membrane found in the upper nasal cavity. • Olfactory cells carry information to the olfactory bulb • The olfactory bulb activates the prefrontal cortex. • Olfactory receptor neurons have a life cycle of about 30 days and are continually created. • Olfactory cells in the olfactory epithelium are stimulated by gases dissolved in the fluid covering the membrane. Somesthesis • Somesthesis - the mechanical senses, including kinesthesis, vestibular sensation, and the skin senses. • Kinesthesis • Communicates information about movement and location of body parts • Receptors found in joints and ligaments Helpful Video