Sensation & Perception Flashcards
Sensation
Transduction - conversion of information from our internal and external environment to electrical signals in the nervous system
Perception
Processing to make sense of sensations, interpret them and their significance
Sensory Receptors
Respond to stimuli and trigger electrical signals
Ganglia
Transmit data from receptors to the Central Nervous System
Photoreceptors
Detect electromagnetic waves (vision)
Hair Cells
Fluid in inner ear responsible for hearing, linear and rotational acceleration
Nocioreceptors
For painful or Noxious stimuli
Thermoreceptors
Detect changes in temperature
Osmoreceptors
Detect the osmolarity of blood; responsible for water homeostasis
Olfactory Receptors
Detect volatile compounds through smell
Taste Receptors
Detect dissolved compounds through taste
Threshold
Minimum amount of stimuli resulting in perception of difference
Absolute Threshold
Minimum stimuli needed to stimulate / activate a sensory system where the stimulus is converted into action potentials; It is the amount of stimulus that an individual can perceive
Conscious Perception
Evoke action potentials long enough to be noticed
Difference Threshold
Minimum difference between 2 stimuli necessary to be perceived by the organism
Weber’s Law
Constant ratio between stimuli to produce a just noticeable difference
change in Intensity of Stimuli (a jnd)
_____________________________ x 100 = K
Intensity of original stimuli
Signal Detection Theory
Changes in our perception of the same stimuli depending on nonsensory internal factors (memories, motive, experiences, expectations etc…) and external (environmental) context
Adaptation
Physiological (sensory) component and psychological (perceptual) component changes our detection of stimuli over time
Cornea
Clear dome-like window in the front of eye
*Gathers and focuses incoming light
Pupil
Hole in the iris
*Allows passage of light from anterior to posterior chamber; contracts in bright light and expands in dim light
Iris
Colored part of the eye
*Controls the size of the pupil thus the amount of light entering the eye
Ciliary Body
Provides aqueous humor (clear liquid in the front of the eye between the lens and the cornea)
Canal of Schlemm
Drains the aqueous humor (clear liquid in the front of the eye between the lens and the cornea)
Lens
Lies right behind the Iris
*Refracts and Controls the curvature of light coming in and can focus near or distant objects on the retina
Retina
In the back of the eye
*Detects images through rods and cones
Sclera
Structural Support
Visual Pathway
Cornea Lens Vitreous Retina (rods and cones) Bipolar Cells Ganglion Cells Optic Nerve Optic Chiasm Optic Tract Lateral geniculate nucleus (LGN) of thalamus Radiation through temporal and parietal lobes Visual cortex (occiptal lobe)
Rods
Are responsible for Night Vision (active at low levels of light): Light and dark
- Increase in number toward the edge (periphary) of the eye
Cones
Are responsible for color detection and fine details (active at higher levels of light)
- Centered in the fovea
Duplicity Theory of Vision
Rods (dim light) and cones (bright light) both create vision
- Light passes through intermediate sensory neurons before reaching and stimulating photoreceptors
Fovea
Middle section of the Retina
Center of eye; only cones (best in daylight vision)
Optic Nerve
Contains no photocepetors; formed bu groups of ganglion cells
Ganglion Cells
Grouped together to form the Optic Nerve
*Receives visual information from photoreceptors via two intermediate neuron types: bipolar cells and retina amacrine cells.
Bipolar Cells
Highlight gradients between adjacent rods and cones
Horizontal Cells (Amacrine)
Important for edge detection and perception of contrasts
Parallel Processing
Simultaneously analyze and combine information regarding
- color (cones)
- shape (parvocellular cells)
- motion (magnocellular cells)
Parvocellular Cells
Responsible for shape; see fine detail in stationary or slow moving objects
Magnocellular cells
Responsible for motion; blurry but moving image
Pinna (Auricle)
Cartilage (fleshy part of the outer ear) that channels sound waves into the external auditory canal
Tympanic Membrane (Eardrum)
- Divides outer ear from middle ear
- Vibrates in phase with the incoming sound wave
Ossicles
3 Smallest bones in the middle ear that transmit and amplify vibrations to the inner ear
- Malleus (hammer)
- Incus (anvil)
- Stapes (stirrup)
Eustacian Tube
Equalizes pressure between middle ear and environment
Endolymph
K+ rich fluid that fills the membranous labyrinth of the ear
Perilymph
Transmits vibrations via fluid from outside world and cushions the inner ear
Organ of Corti
Actual hearing apparatus; hair cells (receptors of hearing) bending is converted from physical stimulus into an electrical signal carried along the nerve fiber connecting to the auditory nerve and the Central Nervous System
Vestibule
Composed of the Utricle and Saccule; sensitive to linear acceleration, balance, determines ones orientation; hair cells resist the motion
Semicircular Canals
Sensitive to rotational acceleration; endolymph resists the motion
Auditory Pathway
Pinna External Auditory Canal Tympanic Membrane Malleus Inca Stapes Oval Window Perilymph Coclea Basilar Membrane Hair cells Vestbulocochlear Nerve Brainstem Medial geniculate nucleus (MGN) of thalamus Auditory Cortex (Temporal Lobe)
Tonotopically
Organization of the cochlea (basilar membrane and apex) allows hair cells to vibrate
Basilar Membrane
High frequency base of the cochlea
Apex
Low Frequency top of the cochlea
Smell
Olfactory chemoreceptors respond to volatile or aerolized compounds
Pheremones
Secreted by an organism to compel another organism to behave a certain way
Olfactory Pathway
Nostril Nasal Cavity Olfactory Chemoreceptors Olfactory bulb Olfactory tract Higher order brain regions (Limbic system)
Tastes
- Sweet
- Salty
- Sour
- Bitter
- Umami (savory)
Somatosensation
Sensitive to pressure, vibration, pain and temperature
Pacinian Corpuscles
Detects deep pressure and vibration
Messiner Corpuscles
Detects light touch
Merkel Discs
Detects deep pressure and texture
Ruffini Endings
Detects stretch
Free Nerve Endings
Detects pain and temperature
2 Point Threshold
Minimum distance between two points of stimulation felt as two distinct stimuli
Physiological Zero
Normal temperature of the skin (86-97 degrees F)
Gate Theory of Pain
- Special “gating” mechanism (located in the spinal cord) can block sensory input from large, thick sensory fibers before the pain is able to receive the pain signals
- Turns pain signals on and off and determine whether we receive it
Kinesthetic Sense
- Perception of the body’s movements and where it is in space; detected by propioceptors (movement sensors)
- Specifically muscle, tendon and joint position
Bottom Up (Data Driven) Processing
- Individual sensory stimuli that combines to create a cohesive image before determining what the object is
- Object perception that responds directly to the components / specific parts of an incoming stimulus on the basis of fixed rules; Then summing up the components to arrive at the whole pattern or object
Top Down (Conceptually Driven) Processing
Object perception that is guided by conceptual processes (memories, expectations, etc…) that allow the brain to recognize the whole object quickly before recognizing its components / specific parts
Perceptual Organization
2 Above processes in tandem with other sensory clues will create a complete picture or idea
Gestalt Principles
Ways for the brain to infer missing parts of a picture when a picture is incomplete
- Proximity
- Similarity
- Good Continuation
- Subjective Contours
- Closure
- Prägnanz
Proximity Principle
Components close together are seen as one unit
Ex; . . . . . . . . . . dots close together seen as one unit not separate dots
Similarity Principe
Similar components (color, shape, size) tend to be grouped together
Good Continuation Principle
Components that appear to follow the same path / direction are grouped; continuation is more likely than abrupt changes in pattern
Ex: ~~~~~~~~~ seen as a continuous squiggle rather than separate components
Subjective Contour Principle
Edges and shapes not actually present are implied by the surrounding objects
Closure Principle
Space enclosed by contour line is perceived as a complete figure
Ex: < > shows a diamond despite not being connected
Prägnanz Principle
- Gestalt Laws operate to create the most stable, consistent and simple figures possible within a given array
- Perceptual organization - regular, simple and symmetrical
Psychophysics
Measures the relationship between physical stimuli and psychological responses to stimuli
Limen
Another word for Threshold
Subliminal Perception
Perception of stimuli below the threshold of conscious awareness
Standard Stimulus
Basis of comparison for other stimuli
Comparison Stimulus
Different from the value of the standard stimulus
Just Noticeable Difference (JND)
Amount of change necessary to predict the difference between two stimuli
Weber’s Constant (Weber’s Fraction
K: the smaller the value the better the sensitivity
change in Intensity of Stimuli (a jnd)
_____________________________ x 100 = K
Intensity of original stimuli
Fechner’s Law
- Expresses the relationship between the intensity of the sensation and the intensity of the stimulus
- Sensation increases more slowly as intensity increases
Response Bias
Tendency of subjects to respond in a particular way due to nonsensory factors (motives, experience, expectations, memories, etc…)
Noise Trial (Catch Trial)
Trial in which the stimulus is NOT presented
Signal Trial
Trial in which the stimulus IS presented
Hits (Trial)
Signal (stimulus) is presented and the subject perceives the stimulus
Misses (Trial)
Signal (stimulus) is presented and the subject does not perceive the stimulus
False Alarm (Trial)
No signal (stimulus) is presented and the subject perceives a stimulus
Correct Negative (Trial)
No signal (stimulus) is presented and the subject does not perceive the stimulus
Sensitivity
Measures how well the subject can sense the stimulus
Receiver Operating Characteristic (ROC) Curve
Graphically summarizes a subject’s response in a signal detecting experiment
Sensory Information Processing Steps
- Reception
- Transduction
- Electrochemical energy is sent to various Projection Areas
- Electrochemical energy sent along varoius Neural Pathways to be processed by the Nervous System
Reception
Receptors react to physical external energy
Transduction
Translation of physical energy into neural impulses or action potentials (electrochemical energy)
Projection Areas
Brain areas that further analyze sensory input
Optic Chiasm
Fibers from the nasal half of both retinas cross paths
- Nasal fibers from the right eye go to the left side of the brain
- Nasal fibers from the left eye go to the right side of the brain
Temporal Fibers
Temporal Fibers of both retinas remain on the same side
- Temporal fibers from the right eye go to the right side of the brain
- Temporal fibers from the left eye go to the left side of the brain
Feature Detection Theory
Cetain cells in the cortex are maximally sensitive to certain features of stimuli
Simple Cells
Give information about orientation and boundaries of an object
Complex Cells
Give more advanced information about orientation such as movement
Hypercomplex Cells
Give information about abstract concepts such as object shape
Illumination
Physical, Objective measurement that is simply the amount of light falling on a surface
Brightness
Subjective impression of the intensity of a light stimulus
Rhodopsin
Photopigment found in Rods
- Contains Retinal (Vitamin A derivative)
- Contains Opsin (protein)
Bleaching
When a molecule of rohodpsin absorbs a photon of light and the pigment is decomposed or split into Retinene and Opsin
- Takes time for the pigments to regenerate
Simultaneous Brightness Contrast
Target area of a particular luminance appears brighter when surrounded by a darker stimulus than when surrounded by a lighter stimulus
Lateral Inhibition
- Adjacent retinal cells inhibit one another; if a cell is excited, neighboring cells will be inhibited
- Sharpens and highlights the borders between dark and light areas
Trichromatic Theory (Young-Helmholtz)
- Retina contains 3 different types of color receptors (cones) sensitive to different colors: Red, Blue and Green
- All colors are produced by combined stimulation of these receptors; ratio of activity in the receptors that determines color
Opponent-Process Theory of Color Vision
- (Ewald Hering)
Color receptors are arranged in opposing pairs: Red-Green, Blue-Yellow and Black-White; one color inhibits the pair and the other excites the pair
AfterImages
Visual sensation that appears after prolonged or intense exposure to a stimulus
Interposition (Overlap)
Cue for Depth Perception; when one object (A) covers or overlaps with object (B) we determine object (A) as being in front
Relative Size
Cue for Depth Perception; as an object gets farther away the image gets smaller on the retina
Linear Perspective
Cue for Depth Perception; Convergence of parallel lines in the distance
Texture Gradients
Cue for Depth Perception; Variations in perceived surface texture as a function of the distance from the observer
Motion Parallax
When an observer moves; the apparent relative motion of several stationary objects against a background hints to their relative distance
Kinetic Depth Effect
When the object (not the observer) moves; the motion of that object gives us cues about the relative depth of parts of the object
Binocular Disparity (Stereopsis)
Cue for Depth Perception requiring 2 eyes; Distance between the eyes provides us with two slightly disparate view of the world
Figure
The integrated visual experience that stands out at the center of attention (what we focus on)
Ground
Background against which the figure appears
Real Motion
Actually moving the light
Apparent Motion
Illusion that occurs when two dots flashed in different locations on screen seconds apart are perceives as one moving dot
Induce Motion
Illusion of movement occuring when everything around the spot of light is moved
Autokinetic Effect
Illusion that occurs when a spot of light appears to move erratically in a dark room, simply because there is no frame of reference
Motion Aftereffect
When you first view a moving pattern and then you view a spot of light; the light will appear to move in the opposite direction of the pattern
Distal Stimulus
The actual object or even out there in the world
Proximal Stimulus
The information our sensory receptors receive about the object
Habituation (Visual Perception in Infants)
- When a new stimulus (A) is presented the infant will orient toward it. When the infant stops attending to the stimulus (A) a new stimulus (B) will be introduced - if the infant orients toward the newest stimulus (B) it is inferred that the infant can tell the difference between the 2 stimulus (A and B)
Preferential Looking
Visual Perception in Infants:
- When two different stimuli are presented side by side - the one the infant looks at the longest is the preferred stimuli
- Generally prefer looking at relatively complex and socially relevant stimuli
Frequency
Number of cycles per second (measure in Hertz (Hz))
- the shorter the wavelength the higher the frequency
- Humans sensitivity ranges from 20Hz - 20,000Hz
Intensity
Amplitude or height of the air-pressure wave (measured in bels or decibels (dB)
- The more dB the noisier the sound is
Loudness
Subjective experience of the magnitude or intensity of the sound
Pitch
Subjective experience of the frequency of the sound
Timbre
Quality of a particular sound; related to the complexity of the sound wave or the mixture of frequencies
Cochlea
Part of the inner ear filled with saltwater-like fluid called Cochlear Fluid
Place Theory
Each different pitch causes a different place of the basilar membrane to vibrate; The place of disturbances causes different hair cells to bend
Frequency Theory
Basilar membrane vibrates as a whole - that rate of vibration equals the frequency of the stimulus and is directly translated into the appropriate number of neural impulses per second
Taste Buds
found in little bumps on the tongue called Papillae
Smell Receptors
Located in the upper nasal passage of the nose called the Olfactory Epithelium
Vestibular Sense
Sense of balance and of our bodily position relative to gravity; Receptors for balance are found in the semicircular canals in the inner ear
Selective Attention
Filter between sensory stimuli and our processing systems; Controls loudness that dampens (but does not completely block out) ancillary stimuli