Unit 3 - Sensation and Perception Flashcards
Sensation
Process by which we detect physical energy from the environment and encode it as neural signals.
Perception
Process by which the brain organizes and interprets sensory information.
Bottom-up processing
Analysis begins with the sense receptors and works up to the brain’s integration of sensory information; inductive reasoning (logical thinking begins with details and then forms broad perceptions or generalization) is an example of bottom-up processing.
Top-down processing
Information processing guided by higher-level mental processes; deductive reasoning (logical thinking approach that begins with a general idea and then develops specific evidence to support/refute it) is an example of top-down processing.
Absolute Threshold
Minimum stimulation needed to detect a stimulus 50 percent of the time.
Just Noticeable Difference (jnd)
Minimum difference between TWO stimuli that a subject can detect the difference between the two stimuli.
Weber’s Law
States that the just noticeable difference between two stimuli is a constant minimum percentage of the stimulus; If the difference of 105 in weight is noticeable, Weber’s Law predicts a person could discriminate 10 and 11 pound weights or 50 and 55 pound weights.
Sensory adaptation
Decreased sensitivity that occurs with continued exposure to an unchanging stimulus.
Sensory habituation
Our perceptions of our senses depend on how focused we are on them; for example, you may no longer hear the trains going by our home after living in that house for a period of time.
Transduction
Process by which receptor cells in the eye, ear, skin, and nose convert environmental stimuli into neural impulse.
Hue
The color we experience, comes in the basic colors of red, green, or blue.
Wavelength
Distance from one peak of one light or sound to the next; gives rise to the perceptual experiences of hue (color) and pitch (sound).
Intensity
Determined by amplitude of the waves (brightness of color or loudness of sound); any sound that exceeds 85 decibels in amplitude or intensity will damage the auditory system.
Cornea
Transparent structure that covers the front of the eye.
Pupil
Adjustable opening in the eye through which light enters.
Iris
Ring of muscle tissue that forms the colored part of the eye and controls the diameter of the pupil.
Lens
Transparent structure of the eye behind the pupil that changes shape to focus images on the retina.
Accomodation
Process by which the lens of the eye changes shape to focus near objects on the retina.
Retina
Light-sensitive, multilayered inner surface of the eye that contains the rods and cones as well as neurons that form the beginning of the optic nerve.
Fovea
The central point of focus in the retina around which the eye’s cone cluster.
Rods
Retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision when the cones don’t respond; you have 120 million of them.
Cones
Retinal receptors that are concentrated near the center of the retina and that function in daylight or in well-lit conditions; detect fine detail and give rise to color sensations; you have 6 million of them.
Optic Nerve
Carry neural impulses from eye to brain.
Blind spot
Region of retina where optic nerves leave the eye; no rods or cones are in this area = no vision here.
Nearsightedness
Condition in which nearby objects are seen clearly but distant objects are blurred because light rays reflecting from them converge in front of the retina; also called myopia.
Farsightedness
Condition in which distant objects are seen clearly but nearby objects are blurred because light rays reflecting from them strike the retina before converging; also, called presbyopia.
Young-Helmholtz Trichromatic Theory
Three color theory – retina contains red, green, and blue-sensitive color receptors that in combination can produce the perception of any color; explains first state of color processing and color blind.
Monochromatism
Complete color-blindness in which all colors appear shades of grey from white to black.
Dichromatism
Color deficiency because only two of the three primary colors can be detected.
Opponent-process theory
Color vision depends on pairs of opposing retinal processes in the brain (red-green, blue-yellow, black-white); explains the second stage of color processing and afterimages.
Prosopagnosia
Inability to recognize faces as familiar due to an issue with the connection within temporal lobe, occipital lobe, and fusiform gyrus.
Blindsight
Neurological condition where one can perceive the location of an object despite being blind.
Color constancy
Perception that familiar objects have consistent color despite changes in illumination that shift the wavelengths they reflect.
Audition
Sense of hearing
Pitch
A sound that is determined by its frequency or number of complete wavelengths that can pass a point in time. Frequency is directly related to wavelength. The longer waves produce lower pitch; shorter waves produce higher pitch.
Amplitude
Affects loudness meaning how much pressure is being forced through the air; measured in decibels (dB).
Frequency
Number of wavelengths cycles in a unit of time; measured by hertz (Hz) and humans here from 20 to 20,000 Hz.
Auditory Canal
Used to catch sound and direct it into the ear.
Middle Ear
Chamber between the eardrum and cochlea containing the ossicles or the three bones. (Hammer, anvil, stirrup) that concentrate the eardrum’s vibrations on the cochlea’s oval window.
