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Transcript
Vision Visual Process… light enters…the cornea passes through the pupil (controlled by the iris) reflects off of the lens to the retina o once in the retina… the light is detected by rods or cones → bipolar cell → ganglion cell (whose axons make up the optic nerve) → thalamus → visual cortex Rods vs. Cones (color) CONES Number Location Color sensitive? Sensitivity in dim light? Ability to detect detail? Number of bipolar cells? RODS Vision HEARING (Audition) Physics of sound… ● Frequency (pitch): number of cycles completed by a wave in a given amount of time, usually a second ● wavelength: the distance from the peak of one wave to the peak of the next. ● long wavelengths = low frequency/pitch ● short wavelengths = high frequency/pitch ● Amplitude/Intensity (Loudness): physical strength in a wave, usually determined by the height of the wave (from peak to valley) ● decibel: measuring unit for sound strength/energy Auditory process ● outer ear (pinna) → auditory canal → tympanic membrane (eardrum) → ossicles (bones) of the middle ear → oval window → cochlea → basilar membrane (hair cells) → auditory nerve → auditory cortex Perceiving Pitch ● 2 theories ● Frequency theory: the basilar membrane vibrates at the same rate as incoming sound waves, triggering neural impulses at the same rate ● explains low-pitched sounds ● Place theory: different frequencies cause vibrations at different locations (hair cells) along the basilar membrane, triggering the neurons at that place ● explains high-pitched sounds Hearing Loss ● As we age, we lose the ability to detect the higher frequency/pitch sounds ● Why? ● Conduction deafness: inability to hear resulting from damage to the structures of the middle ear ● Sensorineural deafness (nerve deafness): inability to hear resulting from damage to the cochlea, hair cells or auditory nerve ● Cochlear implant? Good or bad? Vision Blind spot? Place where your optic nerve exits retina…no receptors Visual information processing o feature detectors – neurons in the visual cortex that respond to specific features…edges, lines, angles and movements ▪ from these, the brain (frontal, parietal and temporal lobes) assembles the image ● parallel processing – the brain processes several aspects of a problem simultaneously Color vision o Young-Helmholtz Trichromatic theory: sensation of color is due to 3 cones in the retina – red, blue, green ▪ color deficiency (color blindness) because of lack of or weakened cone, usually red or green cone o Opponent-process theory: color is the product of opposing pairs of receptors – black/white, yellow/blue and red/green ▪ color is produced when one receptor is stimulated and one is inhibited ● afterimages – occur when active color receptors become “tired” Color constancy – the color of an object will remain roughly constant as the lighting and wavelengths change/shift