Sensation And Perception Flashcards
Sensation
Taking in physical, auditory, visual, electromagnetic and other kinds of stimulus from internal and external environment and converting it into electrical signals/action potential and transmitting it to the CNS
Perception
This is defined as the processing of the info that has been transmitted to CNS. Basically make sense of the information received
Sensory receptors
Are neurons that pick up stimulus by triggering electrical signals that carry info to CNS
Distal stimuli
These are outside the body. These do not interact directly with the sensory receptors. They produce photons, heat, light etc which then interact with sensory receptors
Proximal stimuli
These kind of stimuli directly interact with and are sensed by sensory receptors. These could be sound waves, light, heat etc
What is the name of the study that deals with the relationship between physical nature of stimuli and the way we sense and perceive it?
Psychophysics
Transduction-
This process converts stimulus to electrical signals or action potential
Ganglia
Cluster of nerve cells found outside CNS
Name the 7 important sensory receptors in humans
MN2OP2T
- photoreceptors
-mechanoreceptors - thermoreceptors
- nocicreceptors
- osmoreceptors
- taste receptors
- olfactory receptors
Photoreceptor
Respond to light and electromagnetic waves in visible spectrum (basically sight)
Mechanoreceptor
Respond to pressure or movement. Like hair cells in inner ear detect motion of fluid
Nociceptor
Respond to painful and harmful stimulus
Somatosensation
Sensing a stimulus against our own skin
Olfactory receptors
Respond to volatile compounds THAT IS BASICALLY SMELL
Thermoreceptors
Respond to heat and temperature change
Osmoreceptors
Respond to osmolarity of blood
Taste receptors
Respond to dissolved compounds BASICALLY TASTE
Threshold
Minimum amount of a stimulus required to render perception
What are three types of thresholds?
- absolute threshold
- threshold of conscious perception
- threshold difference
______ is the minimum amount of stimulus energy required to activate sensory receptors and take up the sensations and convert them into action potential to reach CNS through ganglia?
Absolute threshold
What is threshold of conscious perception ?
It is the minimum stimulus that can generate enough action potential to reach the CNS and be perceived
Threshold difference?
Minimum difference between two stimuli that can help differentiate between the two
What law explains that noticeable differences between two stimuli is best explained in ratios and remains constant ?
Weber’s law
Relation of adaption and threshold
Adaptation increases the threshold because as we get more adapted to a stimulus, it is less likely to notice difference when the fluctuations are small
Relationship between adaptation and threshold
Threshold increases as we get adapted to a stimuli
Signal detection theory
Studies how internal and external factors influence thresholds of sensation and perception
Signal detection trial with signal present
Noise trial
Signal detection trial with signal a absent
Catch trial
Outcomes for signal detection theory
- hit- signal present and detected
- miss- signal present but not detected
- false alarm - signal absent but detected
- correct negative- signal absent and not detected
Thick outer layering of eye
Sclera
Nutrition is supplied to the eyes by
- retinal vessels
- choroidal vessels
Layer before sclera
Choroid
Innermost layer of the eye
Retina - contain photoreceptors
Cornea
Dome like window in front of the eye - gathers and focuses incoming light
Front of the eye is divided into
2 parts
Anterior chamber and posterior chamber
Pupil
The whole through which light enters - surrounded by iris
Iris
Coyotes part of the eye
- made of up
• dilator pupillae- pupil opens under sympathetic stimulation
• constrictor pupillae- pupil dilates under parasympathetic stimulation
Ciliary body
• produces aqueous humor (present in front part of the eye
• ciliary muscles - helps in accommodation in the eye by stretching suspensory ligaments
Aqueous humor drains into?
Canal of schlemm
Accomodation
Lens changing shape to focus on objects at different distances
Vitreous humor
Inside the eye - supports retina
Duplicity theory of vision
Retina contains 2 photoreceptors
• rods- light and dark
• cones - color
Facts about rods
- signal pigment rhodopsin
- more functional
- do not detect fine details well
Central section of retina that contains cones
Macula
Center of macula
Fovea
Region devoid of photoreceptors
Blind spot
Photoreceptor connection
Rods/cones ——> bipolar cells——> ganglion cells ——-> optic nerve
Amacrine and horizontal cells
-Helps edge detection
- received info from retinal cells
Visual pathway
Connector of eye to brain and flow of visual info along these connections
Describe Visual pathway
Cornia~pupil~lens~retina ~ rods/cones~bipolar cells~ganglion cells~optic nerve~optic chiasm~optic tract~ lateral geniculate thalamus ~occipital lobe through parietal and temporal lobe
Basic working of eye
Right side object is formed on the left side of the retina
LGN is located in
Thalamus
Optic chiasm
Crossing of nasal retinal fibers from both eyes
Optic tract
Pathway after optic chiasm
When color, form, motion and depth are processed simultaneously. What is the name of the processing
Parallel processing
Cones perceive
Color
Form is perceived by
Parvocellular cells
Movement is perceived by
Magnocellular cells
Depth is perceived by
Binocular neurons
Feature detector cells
Detects very particular individual features
Ear has dual functions
- hearing
- vestibular sense (balance, detection linear and rotational acceleration)
Parts of an ear
OUTER MIDDLE INNER
Structure of the ear that collects sound
Pinna
Pinna is connected to?
External auditory canal
Pinna —> auditory canal ——> ?
Tympanic membrane (eardrum)
Parts of outer ear
Pinna, external auditory canal and eardrum
High frequency =
More vibrations
Ossicles
3 little bones in middle ear
-malleus
-incus
-stapes
Oval window
Point where base of stapes connects to cochlea
Eustachian tube
Connects middle ear to nasal cavity
Inner ear
Bony labyrinth - contains cochlea, semicircular canals, and vestibule
Membraneous labyrinth- all three structures form this
Perilymp
Fills bony labyrinth
Endolymph
Potassium rich fluid fills membraneous labyrinth
Cochlea is divided into
3 scalae
Main hearing part of cochlea
Middle scala
Tectorial membrane - immobile and on top of organ of corti
Organ of corti - main organ, contains hair cells bathed in endolymp
Basilar membrane - thin membrane on which organ of corti sits
Purpose of round window
Permits perilymph to move why dislocating
Vestibule
Utricle + saccule - contain special hair cells covered with otoliths(which resists motion when body is moving and send s signal to brain
Linear acceleration
Rotational acceleration is perceived by
Semicircular canals
- each end is swelled called ampulla containing hair cells
Auditory pathway
Pinna ~ external auditory canal ~ eardrum ~ ossicles ~oval window~ perilymph cochlea ~basilar membrane~ organ of corti~hair cells~ vestibulocochlear nerve~brainstem~ medial geniculate nucleus in thalamus ~ temporal lobe
Superior olive
Auditory
- localizes sound
Inferior colliculus
In mid brain
For reflex actions
_________is present over hair cells
Stereocilia
Hair cells on tectorial membrane function
Amplifying sound
Place theory
Pitch of the sound is determined by the location of the hair cells on basilar membrane
How is cochlea organised
Tonotypically
What does tonotypically organized mean
Low pitch cause hair cells to vibrate at the bottom
High pitch cause hair cells to vibrate at the apex
What is the only sense that does not pass through thalamus
Smell
Smell sense
Responds to volatile and aerosolized compounds
Smell receptors are called
Olfactory Chemoreceptors
Olfactory Chemoreceptors location?
Upper part of nasal cavity on epithelium
Chemical releases by the body outside in the environment
Pheromones eg - sweat, urine, body oil etc
Olfactory pathway
Nostril - nasal cavity - olfactory chemoreceptors - olfactory bulb- higher order brain regions and limbic system
Basic tastes
Sweet
Sour
Salty
Savoury
Bitter
Taste receptors
Chemoreceptors or taste buds (cells)
Chemoreceptors are sensitive to
Dissolved chemical
Taste buds are found
On bumps on tongue called papillae
Somatosensation has 4 modalities. Name them
PPVT
PRESSURE
PAIN
VIBRATION
TEMPERATURE
5 cells under somatostatin
Pacinian corpuscles - deep pressure and vibration
Merkel - deep pressure and testure
Ruffini - stretch
Open nerve endings - pain and temperature
Meissner corpuscles - mild touch
Two point threshold
Minimum distance which needs to be there between two different point of stimulation on to distinguish between the two stimuli
Physiology zero
Normal body temperature
Gate theory of pain
Pain signal can be turned on or off
Spinal cord has the ability to modulate the pain before sending signals to the brain
Kinesthetic sense
Ability to tell where the body is in space
Kinesthetic sense is also called
Proprioception
Proprioception receptors are called
Proprioceptors
Bottom up processing
Parallel processing + feature detection takes place then the whole object is identified
Top down processing
First object is identified through memory and recognition and then the components are identified.
When bottoms up and top down processing are combined
Perceptual organisation
Gestalt principles
Help fill gaps
What are the two visual cues ?
- Monocular cues
- Binocular cues
Monocular cues
Require one eye
-interposition - objects overlap and find one in front appears to be closer
-linear perspective-parallel lines converge at distance
-motion parallax - objects closer seem to move faster
- relative size - objects appear larger than they are
Binocular cues
Needs two eyes
- retinal disparity
- convergence
Binocular cues
Needs two eyes
- retinal disparity
- convergence
Retinal disparity
There is a slight difference between the images produced at two retinas
Convergence
Brain detects the angle between objects and bring the object into focus
Constancy
Perceiving an object same in different environment
Gestalt principles
- Law of proximity
- Law of similarity
- Law of closure
- Law of contour/subjective contour
- Law of good continuation
Law of proximity
Objects close to each other are considered unit
Law of good continuation
Elements that appear to follow the same path seems to be together
Law of subjective contour
Contours/ shapes are seen even if they are not drawn
Law of similarity
Elements that look alike are grouped together
Law of closure
If there is a space between contours, it’s perceived as if the shape is closed
What is law of pragnaz?
That perceptual organisation will always be regular, simple, and symmetric
