SENSATION AND PERCEPTION Flashcards
SENSATION + PERCEPTION
- feeling from physical stimulation
- how we organize or experience the sensations
3 Steps in Sensation
1) Reception
2) Sensory transduction
3) Neural pathways
Reception
- receptors for sense detect stimulus
Receptive field
- part of world that triggers neurons
Sensory transduction
- physical senstion is changed into electrical messages and brain can understand
Neural Pathways
- info is understood
Nativist theory
- perception and cognition are innate
Structuralist theory (bottom up or top down?)
- perception is sum total of sensory input
- world is understood by bottom-up processing
Gestalt psychology (bottom up or top down?)
- revolves around perception and that people see world as organized wholes
- world is understood through top down processing
Current thinking of sensation and perception theory?
- perception is innate and learned/conceptual
Perceptual development
- increasing ability for child to make finer discrimination among stimuli
James Gibb
- perceptual development
Optic array
- all of a thing a person sees
Photons and waves
- measure brightness and wavelengths
Hue
- color
- dominant wavelength of light
Brightness
-physical intensity
Cornea
- clear protective coating on eye
Lens
- located behind cornea
Ciliary muscle
- bend the lens to accommodate and focus image of outside world onto retina
Retina
- back of the eye that receive lights images from lens
- composed of photoreceptor cells
Receptor cells
- on the retina are responsible for sensory transduction
How does sensory transduction occur?
- through chemical alteration of photopigments
Rods
- sensitive to dim light and used for night vision
- concntrated on sides of retina for periperal vision
Cones
- concentrated on center of retina (fovea)
- greatest visual acuity for fine detail
- sees color and daylight
- better than rods because there are fewer cones per ganglion cell
Fovea
- center of retina where cones are concentrated
Process of light passing through receptors
- after light passes through receptors ==> horizional cells ==> bipolar cells ==> amacrine cells ==> ganglion cells (make up the optic nerve)
Describe the visual pathway starting from the eyes
- eyes connect to cerebral cortex through visual pathway
- consist of optic nerve connects each eye to brain ==> optic chiasm (half of fibers from optic nerve cross) ==> striate cortex ==> visual assocation areas of cortex
Optic chiams
- where 50% of fibers from one eye cross over and join optic nerve from other eye
- ensures brain see full picture
- left visual field is processed in right side of brain and vice versa
Opponent-color or opponent process
- theory by Ewald Hering
- 2 types of color sensitive cells exists = blue-yellow and red-green
- one color is stimulated then other color is habituated
Afterimage
- Ewald Hering
- focusing on one color then looking at white image will produce afterimage of the habituated color e.g. red ==> wall ==> green afterimage
Tri-color theory or component theory
- Young and Helmholtz
- 3 types of receptors in retina:
1) red cones
2) green cones
3) blue cones
Young and Helmholtz
- Tri-color theory or component theory
Where does the opponent process theory
- at work in lateral geniculate body
Where does the tri-color theory seem to be at work?
- in the retina
Lateral inhibition
- eyes to see contrast and prevents repetitive information from being sent to brain
- once receptor is stimulated the nearby ones are inhibited
What is Helmholtz famous for?
- discovering color blindness
Davic Hubel and Torsten Wiesel
- cells in visual cortex are complex and specialized to respond to certain types of stimuli
e. g. vertical lines
Visual Field
- entire span that can be percieve or detected by eye at given moment
Figure an Ground Relationship
- relationship between meaningful part of picture (figure) ad background
Binocular disparity
- most important depth cue
- view objects from 2 different angles which allow us to create a 3D picture
Apparent size
- clues about how far away an objects is by knowing how big the object should be
Interposition
- overlap of objects shows which object is closer
Linear perspective
- showing us features we are familiar with
e. g. 2 lines converging in the distance
Texture gradient
- how we see texture or fine detail differently from different surfaces
Motion Parallax
- how movement is percieved through the displacement of objects over time
- motions seems different for nearby and far away places e.g. fa away ships sem to move more slowley
Gibson and walk
-visual cliff apparatus study to see if depth perception is innate
Afterimage
- aka McCollough effect are percieved bc of fatigue receptors
- oppositional system for eeing color = once one is overstimulated it can no longer response and is overshadowed by it’s opposite
Dark adaptation
- regeneration of retinal pigment
Mental set
- why we see what we expect to see
Pragnanz
- overarching Gestalt idea that experience will be organized as meaningful, symmetrical and simple whenever possible
Closure
- tendency to complete incomplete figures
Proximity
- tendency to group together items that are near eachother
Continuation or good continution
- tendency to crate a whole or detailed figure based on our expectations rather than what is seen
Symmetry
- tendency to make figures out of symmetrical images
Constancy
- how people percieve objects in way that they are familiar with them regardless of changes in acual retinal image
e. g. book is always percieved as rectangle
Size constancy
- knowing that an elephant is large no matter how it might appear
Color constancy
- knowing the color of object even with tinted glass
Minimum principle
- tendency to see what is easiest of logical
Ambiguous figures
- percieved as 2 different things depending on how you look at them
Figure- ground reversal patterns
- ambiguous figures percieved as 2 different things depending on which part you see as the figure and which part you see as the background
Impossible objects
- been drawn and can be perceived but are geometrically impossible
Moon illusion
- shows how context affects perception
- moons look larger when seen on horizon than seen in te sky
- visual cues make moon seeem more distant than sky
Phi phenomenon
- tendency to percieve smooth motion
- explains why motions if inferrd when there is none by flashing lights
Apparent motion
- when motion is inferred when there is non
e. g. in cartoons
Muller-Lyer illusion
- most famous visual illusion
- 2 horizontal lines of equal lengths appear unequal because of orientation of arrow that marks the end
- inward arrows make line seem shorter
Ponzo illusion
- 2 horiztontal lines of equal length appear unequal becuase of 2 vertical line that slant inward
Autokinetic effect
- single point of light viewed in dark will appear to shake or move
- reason is constant movement in our own eyes
Purkinje shift
- way that percieved color brightness changes with level of illumination in room
- lower illumination the extreme colors are less bright
Pattern recognition
- explained by template matching and feature detection
Template matching
- pick out shapes that match what you are looking for
Feature detection
- concentrate on shape you are looking for to scan
Prosopagnosia
- inability to recognize faces
Robert Fantz
- infants prefer complex and sensical displays
Absolute threshold
- minimum amount of stimuli that can be detected 50% of time
Differential threshold
- AKA just noticable difference
- minimm difference that occur between 2 stimuli for them to percieve as different
- defined by E.H. Weber
E.H. Weber
- differential threshold or just noticable difference
Terminal threshold
- upper limit above which the stimuli can no longer be percieved
Weber’s law
- stimulus need to be increased by a constant fraction of original value in order to be noticed as different
==> K(the constnt fraction) = change in increase in intenity for JND/original intensity
Fechner’s law
- more complicated tan Weber’s law
- strenght of stimuli must be signiicantly increased to produce a slight difference in sensation
==> S(sensation strengh) = K log R (a logarithm of the original intensity)
J.A. Swet’s Theroy of Signal Detection (TSD)
- subjects detect stimuli because they want to
- factors in motivation
- explains why subjects respond inconsistently
Response bias
- related to theory of signal detect
- interplay between response bias and stimulus intesnsity determines response
False alarm
- detect stimulus that is not there
Hit
- correctly sensing a stimulus
Miss
- failing to detect a present stimulus
Correct rejection
- Rightly stating that there is no stimulus
Receiver operating characteristic (ROC)
- graphical representations of a subject’s sensitivity to a stimulus
What 2 things are humans sensitive to in sound?
- pitch and loudness
Amplitude
- physical intensity of sound wave that determines loudness
Frequency
- pace of vibrations per second for sound that determines pitch
- low frequency = low pitch
How is frequency measured?
- in hertz (Hz)
- humans best hear around 100 Hz
What are the 3 major part of the ear:
1) Outer ear
2) Middle ear
3) Inner ear
Outer ear
- conists of parts you can see
- pinna and auditory canal
- vibrations travel down the canal to the middle ear
Middle ear
- begins with the tympanic membrane (aka eardrum) that is stretched behind the auditory canal
- 3 small bones (ossicles) the last which is stapes is behind the tympanic memrane
- vibrations bump into membrane and ossicles
Ossicles
1) Malleus
2) Incus
2) Stapes
- found behind the tympanic membrane
Inner ear
- responsible for hearing a balance
- begins with oval window (tapped upon by stapes)
- vibrations are sent to cochlea (contain basilar membrane and organ of corti for hearing) by activating the hair-cell receptors
Traveling wave
- movement from basilar membrane’s hair-cell receptors
Vestibular sacs
- respond to hair movement and sensitive to tilt to give us sense of balance
Receptor cells (in ear)
- activate nerve cells that change information into electrical message that brain processes
What consists of the auditory system that leads to the auditory cortex?
- olivary nucleas
- inferior colliculus
- medial geniculate body
Helmholtz famous for what beside color blindness?
- place resonance theory of sound perception
Place resonance theory of sound perception
- different parts of basilar membrane respond to different frequencies
Sound localization
- achieved in various ways
- e.g. degree in which sounds are more intense than others give us an idea of the origin of sound
- high frequencies = localized by intensity
- low frquencies = localized by phase differneces
Dichotic presentation
- used to study auditory perception and selective attention
Selective attention using dichotic presentation
- verbal messages are presented into ear
- message are different and subject is asked to shadow (repeat) after one message
- process of tuning in to something specific
What is the most primitive sense?
Olfaction
Olfactory bulb
- hair recptors send their message to
- lies in base of the brain
- strongly connected to memory and perception of taste
Gustation (name 5)
1) sweet
2) bitter
3) sour
4) salty
5) umami
Papillae
- aka taste buds
- saliva mixes with food so flavour can flow into papillae
What 4 sense can human skin feel?
- touch
- pain
- warmth
- cold
Free nerve endings
- detect pain and changes in temperature
Meissner’s corpuscles
- detect touch or contact
Pacinian corpuscles
- touch receptors that respond to displacement of skin
- 2 point threshold
- the size of 2 point threshold for touch is largely determined by density and layout of nerves in skin
Physiological zero
- temperature that is sensed as neither warm nor cold
Ronald Melzack and Wall’s
- Gate control theory of pain
- pain is a process vs. simple sensation
- interaction of large an small nerve fibers that run to and from spine
- pain percieved depending on various factors e.g cognition
Phantom limb pain
- feel sensation of pain in limbs that don’t exist in amputees
Endorphins
- neuromodulators that kick in to reduce perception of pain
Orientating reflex
- tendency to turn toward an object that has touched you
Simulations
- perceptual cue that make artifical situations seem real
Subliminal perception
- perceiving a stimulus without conscious awareness
Kinesthetic sense or proprioception
- information from receptors in joints and muscles telling you where the position of your body is
Osmoreceptors
- deal with thirst
Afterimage AKA
The McCollough effect
