Sensation And Perception Flashcards
What is information?
Anything that reduces uncertainty
What is sensation?
Awareness resulting from stimulation of sense organ
What is perception?
The organisation and interpretation of sensations
Psychophysicists
Psychologists that explore changes in physics state corresponding to changes in mental state
Absolute threshold
The intensity of a stimulus that allows an organism to just barely detect it 50% of the time
Weber fechner law relies on the idea that we all have different threshold to the exact same stimulus at different times. What is the law?
Just noticeable different (JND) is NOT fixed. It is a constant proportion of the baseline against which the comparison is being made
Weber fraction
Delta l divided by l = k
Signal detection theory
Differentiates between two independent components that make up a person performance
- Sensory sensitivity (precision)
- Cognitive response (bias)
What limits sensory sensitivity?
Quality of organs
What influences someone’s decisions?
Confidence, motivation, desire to not miss a stimulus, desire to avoid incorrectly detecting a stimulus
What is signal detection theory helpful for?
It helps distinguish between a person sensitive and bias by combing their hit rate with their false alarm rate
Electrochemical activity
How the neutrons interact with environment
Senses detect:
Useful information through physical energy from the environment and convert into electrochemical activity
Sensory transduction
Conversation of physical energy into neural energy
Sensory receptors are:
Class of cells that perform sensory transduction
What are the three sensory receptors?
SES
Simple
Encapsulated
Specialised
Simple receptors describe and function
Free nerve endings
Dendrites exposes to raw environment - touch, pain and pressure
What are Unspecialised cell types
Different environmental stimuli can elicit them / making them imprecise
Encapsulated receptors
Neuron with specialised dendrites
More specialised than free nerve endings ie responds to rapid vibrations
Specialised receptors
Dendrites have been modified making them highly responsive to a specialised environmental stimulation
Specialised senses are:
Vision
Hearing
Smell
Taste
Balance
Touch and pain
Why did specialised senses develop?
Due to evolutionary past which needed to excel in a particular domain
Light
Photons of electromagnetic energy that oscillate with a particular wavelength
Wave length of light
Determine perceived colour
Amplitude of light
Determines its perceived intensity
What do photoreceptors consist of?
Rods and cones
What are the three cones and what are they sensitive to?
Where are they located and what do they do?
Red, green and blue
Sensitive to particular wave lengths
Densely packed in retina providing high resolution neural responses to a visual image
What do rods do? Where are they located?
More sensitive to light
Precedent in retina
Useful for at night
Explain the process of vision
Light refracted by cornea, enters pupil, refracted by lens to cast clear image in retina at the back of the eye
Accomodation is
Lens adjusting thickness to refractive power
What is more powerful lens or cornea? And what makes it more powerful?
Cornea more optically powerful than lens. Refracts incoming light to a far greater extent
Where are rod and cones located?
Deepest layer of retina
What are retinal ganglion cells and where are they located?
Axons of ganglion cells in retina carry visual information from each eye to brain by optic nerve
Located: upper most layer of retina
Optic nerve
Bundled axons of ganglion cells
What is the blind spot?
Area where the axons of the retinal ganglion cells leave the eye in the periphery of the eye
What do visual cortex neurons respond to? And what are they often refered to as as a result?
Patterns of light and dark, direction of motion Signal presence Basic visual feature Orientation Width Direction of motion
Detector neurons
Myopia
Only see objects close
Cornea/lens too strong or eyeball is too large
Hyperopia
Able to see object far
Cornea/lens too weak or eyeball is too small
Presbyopia
Lens unable to increase in thickness thus person can’t see nearby object as it moves closer
What fraction of people are deficient in their red or green cone?
1/50
What is ishihara?
Most widely used colour vision test
Key forms of visual
Information?
Colour
Form
Depth
Motion
How many colours can the 3 cones code for?
16 million
Trichromacy theory
The colour we perceive a colour to be depends on the relative activity of our three types of cones
Opponent process theory:
The colour we perceive depends on the relative activity of three pairings of colour sensitive neurons, in which the activity of one member of each pair inhibits activity of the other member of that pair
How do we perceive visual shapes?
By organising basic visual feature information by neuron of the visual cortex
Gestalt principles help the process of organising basic visual features of information provided by neurons of the visual cortex, what are they?
Group features into:
Figure vs ground object perception
Similar in shape
Close in coherent objects
In a way that favour continuity
What do Monocular depth cues do and what are they?
Guide the way in which visual information is perceived 3D if we are using one eye
Pictorial
Physiological
Motion
Pictorial cues
Relative
Position/height Relative size Linear perspective Light and shadow Interposition/occlusion Aerial perspective
Physiological cues to depth
Accomodation
Explain binocular cues
When objects are close or further away from fixation point the two images start to diverge or converge. Specialised neuron invisual cortex compares inputs from each eye and Devine depth detectors
What do motion detectors do?
Responds to any shape size, shape or pattern only when it is moving in a particular direction and at a particular speed
Beta effect
Series of still images in quick succession with location change slight rah time - create illusion of fluid movement
Phi phenomenon
Two seperate images flicker on and off in alternation perceiving the illusion of motion between two images
What is persistence of vision?
Activation of the motor neurons in the cortex
What is sound?
Vibrational energy in the form of pressure wave emanating from
Some vibrating source
How are pressure waves carried?
Air molecules
What is amplitude of sound, how it is measured and how is it perceived?
Corresponds with intensity of sound and is measured in decibels and perceived as loudness
What is frequency of sound? How is it measured? How is it perceived?
Perceived tone or pitch and measured as hertz - cycles per second
What are mechanoreceptors
Each mechanoreceptor is a cilia that transducers vibrational energy into neural activity
Basilar membrane
Cilia sit
Tectorial membrane
Cilia embedded
How is sound carried?
Enter pinnae in ear canal causing tympanic membrane to vibrate which. Malleus, incus, stakes oscillated and amplified the sound. Stairs creates push pull on oval window of cochlea which causes vibrational energy to pass down basilar and tectorial membrane jerking back and forth results in electrochemical impulses from hair cell.
How are. Shrine of auditory cortex arranges?
Tonitpically
What does tonitopically
Mean?
Neurons of auditory cortex arranges like a keyboard with sensitivity to higher pitch move along surface of cortex towards back of brain
What causes conductive hearing loss?
Inability for tympanic membrane to vibrate sufficiently or ina import for ossicles to transmit vibrations to cochlea
What is sensorineural hearing loss?
Damage to cilia from prolonged loud noise
Tinnitus
Bussing or ringing from damaged cilia
How does a cochlear implant work?
Strip of electrode bypasses damaged cilia. Electrode implanted alongside basilar membrane and directly stimulates cochlear nerve cells
What is binaural perceptual ability
Inputs fromcochlear nerve combine inputs from two ears. Beauties receive stimulation from both ears and allow us to compare sounds from two ears. 2D to 3D
What does vibrational frequency correspond to?
Perceived pitch
What is frequency theory?
Frequency of oscillation of the basilar membrane will produce the same frequency of the basilar membrane
What is the maximum frequency one cilia can detect
100Hz
What is the volley principle?
Between 100-400Hz results in ensembles of cilia firing in response to vibrations sound energy and collectively code the frequency of the sounds
What is place theory?
Base of basilar
Membrane closest to ova
Window is stiffer than apex which is looser thus vibrates more
Location of cilia on basilar membrane can code for up to what frequency?
20000 Hz
What is detecting pure tones important?
Pure tones together produce complex vocalisation type sounds - speech sounds
What is taste?
Chemicals dissolved in saliva
What is smell
Airborne molecules
What do chemoreceptors that makeup taste buds on the tongue do?
Transducer presence of chemicals dissolved into neural impulses
What do chemoreceptors in each of the olfactory bulbs of the brain do?
Transducer presence of chemical in the air we inhale into neural
Impulses
Why is lock and key insufficient to intimating electrochemical impulses?
Chemoreceptors in mouth and nose produce short lived response
Chemicals often get stuck in receptor site thus new chemicals cannot bind to site
Taste bud and epithelial cells
Fastest growing cells in the body
Often absorbed back in the body and recycled
Taste bud
Each bud is made up seperate receptor cells and supporting cells
Taste pore
Exposed receptors of embedded taste bud and this is where sensory transduction occurs
Sensory transduction
Receptors exposes to dissolved chemicals
In saliva turn into neural
Impulses
Olfactory receptor cells
Extension of olfactory nerves into the olfactory membrane of each bulb
What are at the end of each olfactory receptor cell?
Tendrils
What do the tendrils do
They process receptor sites which airborne molecules bind and trigger neural impulses in tonthe receptor sites
Gustatory cortex
Cortical region devoted to processing taste information
Olfactory cortex
Cortical region devoted to processing odour information
Both gustatory and olfactory are between temprable and frontal lobes what else does this connect them with?
Spatial information, spatial memories, things that are relevant to generating emotional responses to stimuli and emotions
Why is it important that smells and taste are linked to memory?
Protect us from bad food
Fitness potential of mate
Infant
Proximal stimulus
Chemical stimulus makes direct contact ie food in taste bud
Distal stimulus
Location of chemical
Uncertain ie smell is airborne
Types of energy sources
Mechanical
Thermal
Chemical
Mechanoreceptors in skin do:
Transducer pressure, vibration, stretch, texture
Proprioceptors
Location: muscles, tendons, joints
Function: respond to position, movement and strain
Most important proprioceptors
Muscle spindle organ
Golgi tendon
Muscle spindle organ
Sits in normal muscle and responds to change in length of
Muscle
Golgi tendon organ
Sit in tendon and responds to stretch and strain in tendon
Function of mechanoreceptors in vestibular system
Detect rushing of fluid in canals due to movement of head
Nocioreceptors
Free nerve endings in skin and throughout the body
Which receptors does the spinal cord receive inputs from and where does it convey it?
Proprioceptors and mechanoreceptors send inputs to spinal cord and then conveys it to somatosensory cortex
Reflex
Information from thermoreceptors go straight to spinal cord and not the brain
Gate control theory of pain
Neuronal signs for pain compete along the way to the brain with touch, pressure and vibration. Thus why we put pressure on something when it’s painful
Nocebo
Experience of pain due to anticipation/expectation of administering painful stimulus
Sensory process
Detect potentially useful info to form patterns of physical energy
Perceptual processes
Organise information into coherent object precepts and then integrate this information with cognitive information
Key feature of perception
Bottom up - occur automatically without cognitive effort (perceptual reflexes)
Key features of perception
Requires integration with cognitive systems in order to achieve object understanding
Visual agnosia
Perceptual problems - difficulty in organising objects that is greater than visual deficiency ie difficulty with object that are cluttered, shadowed etc
Associative agnosia
Deficiency in the integration of perceptual information with cognitive information ie can discern between shapes, patterns and colour but can’t identify function of objects
Prosopagnosia
Inability to recognise faces
Integrative agnosia
Combination of associative and integrative agnosia
Auditory agnosia
Can’t understand/recognise common sounds
Tactile agnosia
Difficulty in recognising objects by touch
Anosognoaia
Deficits in perceiving damage or illness in ones own body
