Young-Helmholtz trichromatic theory - the retina contains different receptors (cones) each sensitive to a different color
- each receptive to a different wavelength
- when stimulated in combination they produce vision in a wide array of colors
Key Terms:
- Audition
- Frequency
- Pitch
- Middle Ear
- Cochlea
- Inner Ear
- Sensoryneural Hearing Loss
- Conduction Hearing Loss
- Cochlear Implant
- Place Theory
- Frequency Theory
Sound Waves
- Auditory stimulus sends particles through the air, creating waves
- The characteristics of these waves determine the nature of the sound we hear
- Frequency - the number of cycles per second
- Pitch - how high or low a a sound is. It is determined by frequency
- Loudness - measured in decibels and determined by amplitude. 0 dB is the threshold of human hearing
- Amplitude - the height of the sound wave
Olfaction
Pain
Gate Theory
Touch
The Ear
Key Terms
Perceiving Pitch
Place Theory - suggest that we hear different pitches because cells are stimulated on different areas of the cochlea
Module 21: Other Senses
- Is experienced in the brain
- is different for every person
Frequency Theory - the membrane vibrates at the same frequency as the sound wave conveying info about pitch
- Theorizes that the spinal cord contains small, pain carrying nerve fibers and larger fibers that conduct other sensory information
- when small nerves are active then pain is experienced
- When there is competing signals from the large nerve cells, the signal from the small fibers is blocked and pain is reduced or eliminated.
- Gate-control Theory
- Chemical Senses
- Olfactory
- Gustatory
- Kinesthesia
- Vestibular Sense
- Sensory Interaction
- Embodied Cognition
Locating Sounds
- Sensory receptors fire when the surface of the skin is touched
- at least 6 types of receptors
- pain, pressure, temperature
- our ears are able to detect minute differences in the stimulus that reaches each ear
- sound waves hit the closest ear sooner
- sound waves are slightly louder in the closest ear
Hearing Loss
Conduction - caused by damage to the mechanical system that conducts sound waves to the cochlea
Sensorineural hearing loss - caused by damage to the cochlea's receptor cells or to the auditory nerves
Module 20:
Hearing
Smell
Body Position and Movement
- A chemical sense
- Each odor is unique
- Detected by large number of sensory receptors in the top of the nasal cavity
- Carried to the brain by the olfactory nerve
- We are capable of detecting a tremendous number of scents
- Strongly associated with emotion and memory
Kinesthesis - our sense of body position and movement
- sensors are located all over our body in the muscles, joints and tendons
Vestibular sense - the sense of body movement and position. Provides a sense of balance
- a product of the semicircular canals and the vestibular sacs
- fluid in these structures triggers hairlike receptors providing information about the location of the head and, by extension, the body
Module 16: Basic Principles
of Sensation and Perception
The minimum amount of a stimulus that must be emitted for human detection
- Researched by Gustav Fetchner
Absolute Thresholds
Vision A candle flame 30 miles away
Hearing A watch ticking 20 ft away
Smell A drop of perfume in 3 room home
Taste 1 tsp sugar in two gallons of water
Touch The wing of a bee on your cheek
dropped from 1cm
Sensation - The process that occurs when special receptors on the sensory organs are activated, allowing various forms of outside stimuli to become neural signals in the brain
Perception - The method by which the sensations experienced at any given moment are interpreted and organized in some meaningful fashion
Key Terms:
- Sensation
- Perception
- Bottom-up Processing
- Top-down Processing
- Selective Attention
- Inattentional Blindness
- Change Blindness
- Transduction
- Psychophysics
- Absolute Threshold
- Signal Detection Theory
- Subliminal
- Priming
- Difference Threshold
- Weber's Law
- Sensory Adaptation
- Gustav Fechner
- Ernst Weber
Transduction - In sensation the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brains can interpret
Psychophysics - The study of how physical energy related to our psychological experience
- Thresholds are not the same for every person in every situation
- Our ability is influenced by experiences, expectations, and psychological state
- Signal detection seeks to predict when we will successfully detect weak stimulus and correctly reject no stimulus in comparison with failing to detect a stimulus or a false alarm
Top-down Processing - the use of pre-existing knowledge to organize individual features into a unified whole. Using our experience, knowledge, and memory to make meaning out of sensory input.
Aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a total mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.
- Stimulus that falls below the absolute threshold for conscious awareness
- It can be detected some of the time but can it influence us, and if so, how much?
- Priming - unconscious activation of associations, predisposing one's perception, memory, or response
- The minimum difference between two stimuli required for detection 50% of the time
- AKA Just noticeable difference
- Noticed by Ernst Weber
- Two stimuli must differ by a constant proportion not amount in order for the difference to be noticed - Weber's law
Bottom-up Processing - the analysis of the smaller features to build up to a complete perception. We take in information through the senses and then process in the brain's association areas.
Ex.
100lb weight requires 5lb for noticeable difference
200lb weight requires 10lb (not 5)
In the brain information is sent to association areas
Stimulus converted into electrical impulse
Take in sensory information
Selective Attention
The focusing of conscious awareness on a particular stimulus excluding other sensory information
Our sensitivity to a stimulus diminishes as a consequence to constant stimulation
- Sight is different because eyes are constantly moving
- adaptive benefit - being alert to novel stimulus has a survival benefit.
Inattentional Blindness
Failure to see objects when our attention is focused elsewhere
Change Blindness - we don't notice changes after interruptions to the visual field.
ESP
Module 17: Influences on Perception
Key Terms:
- Perceptual Set
- ESP
- Parapsychology
Parapsychology - the study of paranormal phenomena
Perceptual Set
Context Effects
A mental predisposition to see things a certain way
- Influenced by our experiences, assumptions, and expectations
- Prevents us from accurately perceiving the truth
Perception and the Human Factor
- The context of a stimulus influences the way we interpret information. Therefore,
- the same stimulus can evoke different perceptions in different situations
- contextual expectations influence our top down processing
- Motivation and emotion also affect the way we interpret a stimulus.
A concept framework that helps us organize and interpret information
Premonitions and Pretensions
Human Factors Psychology
- Psychics' predictions are seldom true
- Many are often so vague and general that they can be retrofitted to events after something happens
- Limited studies reveal that dreams are not prophetic
- Seemingly prophetic events happen no more frequently than one would expect by chance
- Extra sensory perception
- Telepathy - I can read your mind
- Clairvoyance - I can "see" what's happening somewhere else
- Precognition - I can "see" the future
- Psychokinesis - I can bend your spoon
Types of ESP
Perceptual Illusions
Explores the interaction between people and machines.
- facilitates safe and efficient use of technology
- employs natural mapping to design intuitive controls that require no instruction or labeling
- reduces human error in using complex machinery
We perceive objects as being unchanging even if our sensation of the object changes. Constancies apply to light, color, shape and size
Due to the ways in which our brain typically organizes sensory information, we are susceptible distortions or misinterpretations in our interpretation of visual stimuli
Visual Organization
Module 19: Visual Organization and Interpretation
Size Distance Relationship
Experiments in ESP
Visual Capture - the tendency of vision to dominate the other senses
- Gestalt
- Figure-ground
- Grouping
- Depth Perception
- Visual Cliff
- Binocular Cues
- Retinal Disperity
- Monocular Cues
- Phi Phenomenon
- Perceptual Constancy
- Color Constancy
- Perceptual Adaptation
Gestalt - an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into a meaningful whole
The whole is greater than the sum of its parts
- Daryl Bem, Emeritus Cornell University Psi lab and Charles Honorton- reenacted the Ganzfeld experiments
- Reported a 32% success rate in participants being able to receive psychically transmitted images
- Replication was not successful
- Zener Cards
- Created by paranormal psychologist Carl Zener
- Designed to test esp (used by J.b. Rhine)
- Discredited due to flaws in methodology
- No high scoring subject were ever reliably detected
Form Perception
Perceiving Motion
- Our ability to detect motion is imperfect
- Smaller objects seem to be moving faster than larger objects traveling at the same speed
- Stroboscopic motion - we perceive constant motion in a rapid series of similar images
- Phi phenomenon - the illusion of movement created when neighboring lights blink on and off in rapid succession
Figure and Ground - we first determine what part of the image is the relevant object or figure and what is the background
Grouping - we are wired to make sense of visual stimuli by grouping
- Proximity - nearness
- Similarity - likeness
- Continuity - smooth patterns
- Connectedness - we perceive a link between uniform nearby objects
Binocular Cues
Monocular Cues
Retinal Disparity - we note the differences between the images detected in each eye and use the information to calculate distance
Convergence - we detect tension in our eyes as they turn inward to view closer objects. This allows us to determine distance
- Relative size - closer objects appear larger
- Interposition - closer objects block the view of objects further away
- Relative Clarity - closer objects appear more clearly
- Texture Gradient - texture is more coarse and detailed up close
- Relative Height - objects higher in our visual field are perceived as farther away and objects lower in our visual field as closer
More Monocular Cues
- Relative Motion - as we move stationary objects seem to move with us. Objects nearer than the fixation point move backwards. Objects beyond the fixation point move with you
- Linear Perspective - parallel lines appear to converge as they move into the distance.
- Light and shadow - nearby objects reflect more light so dimmer objects seem farther away
Visual Cliff
- Eleanor Gibson and Richard Walk
- Tests depth perception in infants and young animals
- Depth perception is partially innate
Taste
- A chemical sense
- We have different types of taste receptors that are capable of detecting 5 different tastes
- Our hardwired responses to sweet and bitter flavors had survival value
- Aversions form quickly when we eat something that sickens us
Sensory Interaction
- One sense affects the way we experience another
- Information about taste is combined with information about smell and is processed in the temporal lobe of the brain
- Pupil - Adjustable opening that allows light to enter the eye
- Iris - colored part of the eye that controls the size of the pupil
- Lens - focuses the image onto the retina by changing its curvature (accommodation)
- Retina - The light-sensitive inner surface of the eye that contain the receptor rods and cones which process visual information
- Sclera - The white, protective outer layer of the eye
- Cornea - the transparent covering of the pupil and iris. It contributes to the eyes focusing power
Embodied Cognition
- The influence of bodily sensations, gestures, and other states on cognitive preferences and judgements
- Simply, how sensory input from the environment affects the way we think and reason
- Acuity - Sharpness of vision
- Nearsightedness - inability to see clearly at a distance
- Farsightedness - Inability to focus clearly on near objects
- Optic Nerve - carries visual information to the brain
- Blind Spot - point where the optic nerve leaves the eye. No rods or cones are located here
- Fovea - central focal point in the retina. Rods and cones cluster here
- Rods - detect black, white and grey, necessary for peripheral vision. operates in low light conditions
- Cones - located in the center of the retina, cones provide fine detail and color. Do not operate in low light conditions
Visual Information Processing
Parallel Processing
Feature Detection
- We process various aspects of visual stimulus such as color, depth, movement, and form, simultaneously
- Perceptual processing also occurs at this time, allowing us to interpret and make meaning
Hubel and Wiesel (Nobel Prize 1981)
- feature detecting neurons in the occipital lobes' primary visual cortex are specialized to respond to specific features of visual stimulus such as shape, orientation, or movement
- these neurons send the information to the appropriate association areas in the temporal lobe for more sophisticated processing
- Proposed in 1878 by Ewald Hering in response to lingering questions about color vision such as, "Why are there color combinations we do not see like reddish-green?"
- We have three opponent systems: Red-Green, Blue-Yellow, and Black-White
- Those receptors cannot send out information about more than one color at a time
If you continue to stare at a strong stimulus for a prolonged period of time, you desensitize the neurons
Color Constancy
- We understand that objects have a consistent color, even when light conditions change its color
- We use contextual clues to process visual information
its all about the context clues
Taste
Wavelength - the distance from the peak of one light or sound wave to the peak of the next.
Hue - With visible light wavelength determines hue or color
Amplitude - the height of a wave. It determines a color's intensity (brightness)
Key Terms
- Wavelength
- Hue
- Intensity
- Pupil
- Iris
- Lens
- Retina
- Accommodation
- Rods
- Cones
- Optic Nerve
- Blind spot
- Fovea
- Acuity
- Nearsightedness
- Farsightedness
- Feature Detectors
- Parallel Processing
- Young-Helmholtz Trichromatic (three-color) Theory
- Opponent-process Theory
- David Hubel
- Torsen Wiesel