Psychology Chapter 4 Definitions
sensation: simple stimulation of a sense organ.
perception: the organization, identification, and interpretation of a sensation in order to form a mental representation.
transduction: when sense receptors convert physical signals from the environment into neural signals that are sent to the central nervous system.
sensory adaptation: sensitivity to prolonged stimulation tends to decline over time as an organism adapts to current (un-changing) conditions.
psychophysics: methods that systematically relate the physical characteristics of a stimulus to an observer’s perception.
absolute threshold: the minimal intensity needed to just barely detect a stimulus in 50% of the trials.
sensitivity: how responsive we are to faint stimuli.
acuity: how well we can distinguish two very similar stimuli.
just noticeable difference (JND): the minimal change in a stimulus (e.g. in its loudness or its brightness) that can just barely be detected.
Weber’s law: for every sense domain, the change in a stimulus that is just noticeable is a constant ratio of the standard stimulus, over a range of standard intensities.
Signal detection theory (SDT): a way of analyzing data from psychophysics experiments that measures an individual’s perceptual sensitivity (how effectively the perceptual system represents sensory events).
visual acuity: the ability to see fine detail.
retina: a layer of light-sensitive tissue lining the back of the eyeball.
accommodation: the process by which the eye maintains a clear image on the retina.
cones: detect color, operate under normal daylight conditions, and allow us to focus on fine detail.
rods: become active only under low-light conditions, for night vision.
fovea: an area of the retina where vision is clearest and there are no rods at all.
blind spot: a location in the visual field that produces no sensation on the retina.
area V1: the part of the occipital lobe that contains the primary visual cortex.
color-opponent system: pairs of cone types (channels) work in opposition.
visual receptive field: the region of the visual field to which each neuron responds.
binding problem: how the brain links features together so that we see unified objects in our visual world rather than free-floating or miscombined features.
parallel processing: the brain’s capacity to perform many activities at the same time.
illusory conjunction: a perceptual mistake whereby the brain incorrectly combines features from multiple objects.
feature-integration theory: focused attention is not required to detect the individual features that make up a stimulus (e.g. the color, shape, size, and location of letters), but it is required to bind those individual features together.
attention: the active and conscious processing of particular information.
perceptual constancy: the idea that, even as aspects of sensory signals change, perception remains constant.
perceptual contrast: the idea that, although the sensory information from two things may be very similar, we perceive the objects as different.
perceptual organization: the process of grouping and segregating features to create whole objects organized in meaningful ways.
monocular depth cues: aspects of a scene that yield information about depth when viewed with only one eye.
binocular disparity: the difference in the retinal images of the two eyes.
apparent motion: perception of movement as a result of alternating signals appearing in rapid succession in different locations.
spatial acuity: ability to distinguish two features that are very close together in space.
temporal acuity: the ability to distinguish two features that are very close together in time.
multisensory: stimulating multiple senses at the same time.
ventriloquist illusion: the fact that you depend on your visual system for reliable information about spatial location.
change blindness: when people fail to detect changes to the visual details of a scene.
inattentional blindness: a failure to perceive objects that are not the focus of attention.
pitch: how high or low a sound is, as ordered on a musical scale.
loudness: how humans perceive amplitude.
timbre: the quality of sound that allows you to distinguish two sources with the same pitch and loudness.
cochlea: a fluid-filled tube containing cells that transduce sound vibrations into neural impulses.
basilar membrane: a structure in the inner ear that moves up and down in time with vibrations relayed from the ossicles, transmitted through the oval window.
traveling wave: the up-and-down movement that sound causes in the basilar membrane.
inner hair cells: specialized auditory receptor neurons embedded in the basilar membrane.
area A1: the primary auditory cortex in the temporal lobe.
place code: the brain uses information about the relative activity of hair cells (e.g. which ones are more active and which are less active) across the whole basilar membrane to help determine the pitch you hear.
temporal code: the brain uses the timing of the action potentials in the auditory nerve to help determine the pitch you hear.
haptic perception: the active exploration of the environment by touching and grasping objects with our hands.
tactile receptive field: a small patch of skin that relates information about pain, pressure, texture, pattern, or vibration to a receptor.
referred pain: occurs when sensory information from internal and external areas converges on the same nerve cells in the spinal cord.
gate-control theory: holds that signals arriving from pain receptors in the body can be stopped, or gated, by interneurons in the spinal cord, via feedback from the skin or from the brain.
proprioception: your sense of body position.
vestibular system: the three fluid-filled semicircular canals and adjacent organs located next to the cochlea in each inner ear.
olfactory receptor neurons (ORNs): receptor cells that transduce odorant molecules into neural impulses.
olfactory bulb: a brain structure located above the nasal cavity beneath the frontal lobes.
pheromones: biochemical odorants emitted by other members of an animal’s species that can affect its behavior or physiology.
taste buds: the organs of taste transduction.