sensations: the elementary component of an experience such as light and dark, bitter taste and change in temperature
perception: the collection of processes used to arrive at a meaningful interpretation of sensations
5 senses: touch, sight, smell, taste, hearing
psychophysics: a field in psychology in which researchers search for ways to describe the transition from physical stimulus to psychological experience of the stimulus.
transduction: the process by which external messages are translated into the external language of the brain.
absolute threshold: the intensity level at which people can detect the presence of the stimulus 50% of the time
signal detection: technique used to determine the ability of someone to detect the presence of a stimulus.
difference threshold: the smallest detectable difference in the magnitude of 2 stimuli.
weber’s law: the ability to notice a difference in the magnitude of 2 stimuli is a constant proportion of the size of the standard stimuli. 
sensory adaptation: the tendency of sensory systems to reduce sensitivity to a stimulus source that remains constant.
light: the small part of the electromagnetic spectrum that is processed by the visual system.
hue: the dimension of light that produces color
brightness: aspect of the visual experience that changes with light intensity
accommodation: in vision, the process through which the lens changes its shape temporarily to help focus light on the retina
rods: that transduce light energy into neural messages; these visual receptors are highly sensitive and are active in dim light.
cones: that transduce light energy into neural messages; they operate best when light levels are high, and they are primarily responsible for the ability to sense color and fine detail
blind spot: the point where the optic nerve leaves the back of the eye
Receptive field: in vision, the portion of the retina that, when stimulated, causes the activity of higher order neurons to change
Dark adaptation: the process through which the eyes adjust to dim light
Trichromatic theory: theory of color vision proposing that color information is extracted by comparing the relative activations of three different types of cone receptors
Bottom-up processing: processing that is controlled by the physical message delivered to the senses
Top-down processing: processing that is controlled by one’s beliefs and expectations about how the world is organized
Gestalt principles of organization: organizing principles of perception proposed by Gestalt psychologists.These principles include the law of proximity, similarity, closure, continuation and common fate
Recognition by components: the idea proposed by Biederman that people recognize objects perceptually via smaller components called geons
Geons: simple geometrical forms; short for “geometrical icons”
Monocular depth cues: require input from only eye. Includes: relative size, overlap, linear, perspective, shading, and haze
Binocular depth: depend on comparisons between the two eyes
Convergence: cue based on the extent to which the two eyes move inward, or converge, when looking at an object
Phi phenomenon: an illusion of movement that occurs when stationary lights are flashed in succession
Perceptual Constancy: perceiving the properties of an object to remain the same even though the physical properties of the sensory message are changing
Perceptual illusions: inappropriate interpretations of physical reality. Perceptual illusions often occur as a result of the brain’s using otherwise adaptive organizing principles
Sound; the physical message delivered to the auditory system.
Pitch: the psychological experience that results from the auditory processing of a particular frequency of sound frequency is measured in hertz (Hz)
Intensity: pressure amplitude; psychologically changes in intensity are experienced as changes in loudness wave amplitude is measured in decibels (dB)
Place Theory: the idea that location of auditory receptors cells activated by movement of the basilar membrane underlies the perception of the pits
Frequency Theory:the idea that pit perception is determined partly by the frequency of neural impulses traveling up the auditory path
Botton-up processing: controlled by the physical message delivered to the senses
Top down processing: controlled by one’s belief s and expectations
Cold fibers: neurons that respond to a cooling of the skin by increasing the production of neural impulses
Warm fibers: neurons that respond vigorously when the temperature of the skin increases
Pain: an adaptive response by the body to any stimulus that is intense enough to cause tissue damage
Nociceptors: neurons that respond to extreme heat, severe pressure or internal damage such as inflammation
Gate-control theory: the idea that neural impulses generated by pain receptors can be blocked, or gated in the spinal cord by signals produced in the brain
The Pain Path way: site of injury, spinal cord, brainstem, cerebrum
Kinesthesia: in perception, the ability to sense the position and movement of one’s body parts
The vestibular system: receptor system that responds to movement, acceleration and changes in upright posture
part of the ear!- vestibular sacs in the semicircular canals