Chapter 4: Sensing & Perceiving Our World Key Terms Flashcards
Sensation:
A physical process involving the stimulation of our sense organs by features of the outer world.
Perception:
A psychological process involving the act of organizing and INTERPRETING sensory experience.
Sensory adaptation:
The process by which our sensitivity diminishes when an object constantly stimulates our senses.
Transduction:
The conversion of physical into neural information.
Example: cells in the retina change light waves to neural energy.
Absolute threshold:
The lowest intensity level of a stimulus a person can detect 50% of the time.
Signal detection theory:
The viewpoint that both stimulus intensity and decision-making processes are involved in the detection of a stimulus.
Difference threshold:
The smallest amount of change between two stimuli that a person can detect half of the time.
Just noticeable difference (JNS):
The difference threshold that is the smallest change in a stimulus that can be perceived most of the time, another name for difference threshold.
Weber’s law:
The finding that the size of a JND is a constant fraction of the intensity of the stimulus.
Cornea:
The clear, hard covering that protects the lens of the eye.
Pupil:
The opening in the iris through which light enters the eye.
Iris:
The muscle that forms the colored part of the eye; it adjusts the pupil to regulate the amount of light that enters the eye.
Lens:
The structure that sits behind the pupil; it bends the light rays that enter the eye to focus images on the retina.
Accommodation:
The process by which the muscles control the shape of the lens to adjust to viewing objects at different distances.
Retina:
The thin layer of nerve tissue that lines the back of the eye.
Photoreceptors:
Cells in the retina (called rods and cones) that convert light energy into nerve energy.
Rods:
Photoreceptors that function in low illumination and play a key role in night vision; responsive to dark-and-light contrast.
Dark adaptation:
The process of adjustment to seeing in the dark.
Cones:
Photoreceptors that are responsible for color vision and are most functional in conditions of bright light.
Fovea:
A spot on the back of the retina that contains the highest concentration of cones in the retina; place of clearest vision.
Visual acuity:
The ability to see clearly.
Optic nerve:
The structure composed of the axons of ganglion cells from the retina that carry visual information from the eye to the brain.
Blind spot:
The point at which the optic nerve exits the eye; has no receptor cells and therefore nothing is seen.
Optic chiasm:
The point at which strands of the optic nerve from half of each eye cross over to the opposite side of the brain.
Feature detectors:
Neurons in the visual cortex that analyze the retinal image and respond to specific aspects of shapes, such as angles and movements.
Fusiform face area:
A region in the temporal lobe that primarily responds to and recognizes faces.
Trichromatic color theory:
The theory that all color that we experience results from a mixing of three colors of light (red, green, and blue).
Opponent-process theory:
The theory that color vision results from cones linked together in three pairs of opposing colors (blue/yellow, red/green, and black/white), so that activation of one member of the pair inhibits activity in the other.
Depth perception:
The ability to see things in three dimensions and to discriminate what is near from what is far.
Dependent on binocular and monocular depth cues
Binocular depth cues:
Aids to depth perception that rely on input from BOTH eyes.
Binocular disparity:
The difference in retinal images due to the fact that our two eyes are separated by a few inches; this factor is an important cue in depth perception.
Monocular depth cues:
Aids to depth perception that do NOT require two eyes.
Perceptual consistency:
The ability of the brain to preserve perception of objects in spite of changes in retinal image when an object changes in position or distance from the viewer.
Similarity:
A Gestalt law that says we tend to group like objects together in visual perception.
Continuity:
The Gestalt law that says we see points or lines in such a way that they follow a continuous path.
Proximity:
A Gestalt law that says we tend to group objects together that are near one another.
Law of closure:
The tendency to perceive a whole object in the absence of complete information.
Figure:
A specific object in front of an unformed background.
Ground:
The background behind objects or figures.
Timbre:
Is the quality or “color” of a particular sound and is a result of the sound’s complexity or number of sound frequencies.
Tympanic membrane:
The eardrum.
Semicircular canals:
A structure of the inner ear involved in maintaining balance.
Cochlea:
A bony tube of the inner ear, which is curled like a snail’s shell and filled with fluid.
Basilar membrane:
A membrane that runs through the cochlea; contains the hair cells.
Hair cells:
Inner ear sensory receptors for sound that transduce sound vibrations into neural impulses.
Auditory nerve:
The nerve that receives action potentials from the hair cells and transmits auditory information to the brain.
Bodily senses:
The senses based in the skin, the body, or any membrane surfaces.
Touch, temperature, pain, position/motion, balance, and interoception (perception of bodily senses)
Mechanoreceptors:
Receptor cells in the skin that are sensitive to different tactile qualities, such as shape, grooves, vibrations, and movements.
Pain:
A complex emotional and sensory experience associated with actual or potential tissue damage.
Phantom limb pain:
Occurs when a person who has lost an arm or leg continues to feel pain in the lost limb.
Nociceptive pain:
Pain from skin and/or tissue damage or injury.
Heat, cold, chemical irritation, and pressure.
Gate control theory of pain:
The idea that the SPINAL CORD regulates the experience of pain by the BALANCING OF SIGNALS to the brain from small pain nerve fibers and larger non-pain fibers. The pain “gate” opens when more pain signals are sent to the brain than non-pain signals. Pain is blocked when the reverse happens.
Olfactory sensory neurons:
The sensory receptors for smell that reside high up inside the nose.
Olfactory bulb:
A FOREBRAIN structure that sends information either directly to the smell-processing areas in the cortex or indirectly to the cortex by way of the thalamus.
Papillae:
Textured structures on the surface of the tongue; contain thousands of taste buds.
Taste buds:
Structures inside the papillae of the tongue that contain the taste receptor cells.
Taste receptor cells:
Sensory receptors for taste that reside in the taste buds.
Gustatory cortex:
The cortical region of the brain located in the insula area of the frontal lobe where taste sensations are processed and interpreted.
Synesthesia:
An unusual sensory experience in which a person experiences sensations in one sense when a different sense is stimulated.
Afterimages:
Visual images that remain after removal of or looking away from the stimulus.
