Sensation and Perception Flashcards
Sensation
conversion of physical, electromagnetic, auditory and other information from our internal and external environments to electrical signals in the nervous system
Perception
processing of information to make sense of its significance
Distal stimuli
originate outside of the body. These are a part of the outside world
Proximal Stimuli
directly interact with and affect the sensory receptors
Psychophysics
relationship between the physical nature of stimuli and the sensations/perceptions that they evoke
Ganglia
collection of neuron cell bodies found outside of the CNS
Photoreceptors
respond to electromagnetic waves in the visible spectrum
Hair Cells
respond to movement of fluid in the inner ear structure (hearing)
Nociceptors
respond to painful or poisonous stimuli (somatosensation)
Thermoreceptors
respond to changes in temperature (thermosensation)
Osmoreceptors
respond to the osmolarity of the blood
Olfactory Receptors
respond to volatile compounds (smell)
Taste Receptors
respond to dissolved compounds (taste)
Threshold
minimum amount of stimulus that renders a difference in perception
Absolute Threshold
Minimum stimulus energy that is needed to activate a sensory system
Subliminal perception
perception of a stimulus below a given threshold
Threshold of Conscious Perception
minimum stimulus required to consciously perceive the stimulus
Discrimination Testing
way to analyze the
limit in human perceptive ability
Difference Threshold or Just-Noticeable Difference (jnd)
minimum difference in magnitude between two stimuli before one can perceive the
difference
Weber’s Law
states that there is a constant ratio between the change in stimulus
magnitude needed to produce a jnd and the magnitude of the original stimulus
Signal Detection Theory
focuses on the changes in our perception of the same stimuli depending on both
internal (psychological) & external (environmental) context
response bias
tendency of subjects to systematically
responds to a stimulus in a particular way due to non-sensory factors
Catch Trials
stimulus is presented
Noise Trials
signals are not presented
Sclera
- white of the eye
- covers the exposed portion of the eye and is a thick structural layer
Retina
- the innermost layer of the eye and this contains the actual photoreceptors that transduce light into electrical information that the brain can process
- convert incoming photons of light to electrical signals
Duplexity (duplicity theory of vision)
- states that the retina contains two kinds of photoreceptors:
- One set of photoreceptors for light and dark detection
- One set of photoreceptors for color detection
Dilator pupillae
muscle that opens the pupil under sympathetic stimulation
Constrictor pupillae
muscle that constrict the pupil under parasympathetic stimulation
Lens
Controls the refraction of incoming light and lies directly behind the iris
Ciliary Muscle
component of the ciliary body and is under parasympathetic control
Vitreous
Transparent gel that lies behind the lens and supports the retina
Cones
- used for color vision and to sense fine details.
- most effective in bright light
- Come in three forms, and the forms are named after the wavelength of light that they best absorb: S (blue), M (green), L (red)
Rods
- more functional in darkened conditions
- Only allow for sensation of light and dark
- Contain single pigment that is called rhodopsin
- Low sensitivity to detail and not involved in color vision
Fovea
centermost point of the retina that contains only cones
Bipolar Cells
- connect with rods and cones
- These highlight the light gradient between adjacent rods or cones
Ganglion cells
- where bipolar cells synapse to
- These group together to form the optic nerve
Amacrine & Horizontal Cells
- receive input from multiple retinal cells from the same area
- accentuate any slight differences between the information in each bipolar cell, before the input is passed to the ganglion cells
optic chiasm
fibers from the nasal half of each retina cross paths
optic tracts
Reorganized pathways after leaving the optic chiasm
Parallel Processing
ability to simultaneously analyze and combine information regarding color, shape and motion
parvocellular cells
- detect shape
- have high color spatial resolution, which permits them to see very fine detail when an object is thoroughly examined
- only work with slow or stationary object since they have low temporal resolution
magnocellular cells
- detect motion
- have very high temporal resolution, but low spatial resolution
Pinna/auricle
- structure where sound wave first reaches
- The cartilaginous outside part of the ear
- channel sound waves into the external auditory canal
Eustachian tube
- connects the middle ear to the nasal cavity
- Helps equalize pressure between middle ear and environment
endolymph
fluid contained in the membranous labyrinth of the inner ear
perilymph
- extracellular fluid located in the bony labyrinth within the inner ear
- transmits vibrations from the outside world and cushions the inner ear structures
Round Window
permits the incompressible fluids to move within the cochlea
otoliths
- covers modified hair cells in the utricle and saccule
- resist accelerative motion which causes a bend in the underlying hair cells
Vestibule
- portion of bony labyrinth that contains the utricle and saccule
- sensitive to linear acceleration and are used as part of the balancing apparatus and to determine one’s orientation in 3-D space
Place Theory
- location of a hair cell on the basilar membrane determines the perception of pitch when the hair cell vibrates
- Based on the fact that the basilar membrane changes its thickness depending on the location in the cochlea
tonotopically organized
specified hair cells determine the pitch of the sound that the brain interprets
Chemical sense
Responds to incoming chemicals from the outside world
Olfactory Chemoreceptors (nerves)
located in the olfactory epithelium in the upper part of the nasal cavity
Pheromones
ability of smell to carry interpersonal information
Olfactory Pathway
odor molecules are inhaled into the nasal passage and then come into contact with olfactory nerves. Receptor cells are activated and this sends signals to the olfactory bulb. Signals are then relayed via the olfactory tract into higher regions of the brain (including the limbic system)
Somatosensation
Four components: pressure, vibration, pain, and temperature
Pacinian Corpuscles
respond to deep pressure and vibration
Meissner Corpuscles
respond to light touch
Merkle cells (discs)
respond to deep pressure and texture
Ruffini Endings
respond to stretch
Free Nerve Endings
respond to pain and temperature
Two-Point Threshold
minimum distance necessary between two points of stimulation on the skin so that the point will be felt as two distinct stimuli
Physiological Zero
normal temperature of the skin
Gate Theory of Pain
proposes that there is a special “gating” mechanism that can turn pain signals on and off, which would affect whether or not pain is perceived
Kinesthetic Sense/ Proprioception
- Ability to tell where one’s body is in space
- receptors found mostly in the muscle and joints
- role in hand-eye coordination, balance and mobility
Bottom-Up (data-driven) processing
- object recognition by parallel processing and feature detection
- Brain takes the individual sensory stimuli and combines them together to create a cohesive image before determining what the object is
Top-down (conceptually driven) processing
driven by memories and expectation that allow the brain to recognize the whole object and the recognize the components based on these expectations
Perceptual Organization
ability to use the two processes in tandem with all of the sensory clues about an object to create a complete picture or idea
Depth Perception
relies on both monocular and binocular cues
Monocular cues
relative size of objects, partial obscuring of one object by another, convergence of parallel lines at a distance, position of an object, and lighting/shadowing
Binocular cues
slight difference between images projected on the two retinas, and the angle required between two eyes to bring an object into focus
Constancy
idea that we perceive certain characteristics of objects to remain the same
Gestalt Principles
Ways for the brain to infer missing parts of a picture when the picture is incomplete
Law of Proximity
elements close to one another tend to be perceived as a unit
Law of Similarity
similar objects tend to be grouped together
Law of Good Continuation
elements that appear to follow the same pathway tend to be grouped together
Subjective Contours
Contours or shapes are perceived when they are not actually there
Law of Closure
When a space is enclosed by a contour, it tends to be perceived as a complete figure
law of pragnanz
Perceptual organization will always be as regular, simple and symmetric as possible
