Chapter 5:Sensation
Terms
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- Additive Color Mixing
- The mixing of different frequencies of light that combine to form a new color; this kind of color mixing can be observed when different colors of light mix.
- The Inner Ear
- The innermost area of the ear that contains the Cochlea, the Semicircular Canals, and the Vestibular Sacs.
- Sensorineural Hearing loss
- Loss of hearing due to the destruction of the hair cells or neurons in the Cochlea or in the Auditory Nerve.
- Difference Threshold
- The minimum difference in the intensity of a stimulus that can be detected.
- Feature Detectors
- Specialized neurons in the Visual Cortex that react to certain features of visual stimuli, such as lines, objects, angles, shapes, etc.
- Bottom-up Processing
- Analysis of sensations that begins in the sensory organs that transduced the stimuli and ends in the brain.
- Basilar Membrane
- Membrane in the center of the Cochlea that is lined with thousands of tiny cilia, or hair cells, that, when vibrating, cause neural signals to be sent down the auditory nerve.
- Audition
- Another word for hearing.
- The Iris
- A colored muscle that contracts to control the size of the pupil, and thus the amount of light that reaches the retina.
- Nearsightedness
- A condition that results from an excess curvature of the cornea, causing light to be focused at a point in front of the retina; this causes a difficulty to focus on objects that are at a substantial distance.
- Proximal Stimulus
- The stimulus that is interpreted by a sensory organ, which differs from the distal stimulus.
- Acuity
- Sharpness of vision.
- Subtractive Color Mixing
- Mixing of certain frequencies of light that cancel each other out, leaving a new frequency different from either of the original frequencies; this type of color mixing can be observed when mixing pigments.
- Blind Spot
- The area of the retina where the optic nerve leaves the eye, and where no rods or cones exist.
- Signal Detection Theory
- The theory that an Absolute Threshold varies with one's psychological state and past experiences.
- Hue
- Another term for color, which is dependent on the frequency of the light.
- Absolute Threshold
- The minimum intensity of a stimulus that can be detected 50% of the time.
- Distal Stimulus
- The actual stimulus energy that comes from an object or source.
- Perception
- The brain's interpretation of a sensation.
- Conduction Hearing Loss
- The loss of hearing due to the destruction of the mechanisms that conduct vibrations to the cochlea; such mechanisms include the eardrum, the hammer, the anvil, and the stirrup.
- Sensation
- The neural signals that directly result from external stimulation.
- Subliminal
- Describes a stimulus with an intensity below that of the absolute threshold.
- Ganglion Cells
- Cells that receive signals from bipolar cells and send them to the Visual Cortex; the axons of all the ganglion cells make up the Optic Nerve.
- Pitch
- The tone of a sound, which is dependent on the frequency of the sound wave.
- Intensity
- A property of either light or sound that depends on the amplitude of the light- or sound-wave.
- Young-Helmholtz Trichromatic Theory
- The theory that there are three types of color-receptive tissues; those that detect red, those that detect blue, and those that detect green.
- Fovea
- The area of the retina that receives the most focused light; this area contains a high concentration of cones.
- Kinesthesis
- The sense of body position, or the position of our individual body parts relative to one another.
- The Retina
- The back section of the eye that contains photosensitive tissues which transduce light.
- Weber's Law
- The principle that the difference threshold for any stimulus varies directly with the size of the stimulus.
- Farsightedness
- A visual disability that is caused by insufficient curvature of the cornea, and which causes light to be focused at a point behind the eye; this results in a difficulty in focusing on nearby objects.
- The Middle Ear
- Area just beyond the eardrum that contains the hammer, the anvil, and the stirrup.
- Eardrum
- Thin tissue at at the end of the Auditory Canal that vibrates when a sound reaches it and conducts these vibrations to the Hammer.
- Bipolar Cells
- Neurons that relay signals from rods and cones to ganglion cells.
- Frequency Theory
- The theory that we are able to perceive a sound's pitch because the cochlea's neurons (or pairs of them) send signals at the same rate as the frequency of the sound.
- Transduction
- The conversion of external energy into neural signals, in the form of electro-chemical energy.
- Prosopagnosia
- An odd disorder that prevents one from recognizing a face that should be familiar.
- Wavelength
- A property of waves that is inversely proportional to its frequency.
- The Lens
- A transparent organ in the eye, just behind the pupil, that bends and focuses light onto the retina.
- Frequency
- A measure of the number of oscillations per second of a wave; a property of both light and sound-waves that affects our perceptions of such waves.
- Parallel Processing
- The simultaneous processing of several types of information; the default mode that our brains process information.
- Rods
- Photosensitive neurons that detect white, black, and shades of gray; their absolute threshold is below that of cones, which allow them to function in dim light.
- Sensory Interaction
- The effect of one sense on another.
- Color Constancy
- The perception that a color is the same, even if presented in different contexts (such as lighting and object background).
- Pupil
- Opening in the eye that allows light to reach the retina.
- Vestibular Sense
- The sense of the head's angle relative to the horizon; stimuli relevant to this sense are transduced by the Semicircular Canals and the Vestibular Sacs.
- Cones
- Photosensitive neurons that are receptive to color and detail.
- Top-down Processing
- Analysis of sensations that begins in the brain.
- Place Theory
- The theory that we are able to perceive the pitch of a sound because different pitches resonate at different places inside the Cochlea.
- Psychophysics
- The study of how certain characteristics of stimuli affect our perception of those stimuli.
- Sensory Adaptation
- Diminishing sensory reactivity to repetitive or constant stimuli.
- Opponent Process Theory
- The theory that certain neurons are activated by one color and inhibited by its opposite or complementary color.
- Accomodation
- The process by which the lens adjusts its curvature to focus light coming from different distances.
- The Cornea
- The transparent protective layer covering the eye, which also bends light through the pupil and into the lens.
- Gate Control Theory
- The theory that the spine contains a pain gate that opens to let pain signals pass to the brain on thin nerve fibers, but that block pain signals when too many large fibers are active (large fibers are active when receiving sensory informations other than pain, or when the brain is sending a lot of information to the body through the spinal chord).
- The Optic Nerve
- A bundle of axons that send neural information from the retina to the visual cortex.