Week 6 - Sensation And Perception 2 Flashcards
Properties of sound
Sound is caused by vibrations (wave frequency is I second)
Physical feature: Psychological dimension:
Wave frequency (Hz) = pitch Wave amplitude (dB) = loudness Wave complexity = timbre
What is our audible spectrum?
The human ear is sensitive to mechanical vibration from about 20 to 20 000 Hz.
Auditory perception
Different tones excite different areas of the basilar membrane and primary auditory cortex (tonotopic organisation)
Describe the place theory (in pitch perception)
For high pitch, hairs in specific areas of basilar membrane activate specific regions in the primary auditory cortex (5000- 20 000 Hz)
Describe the frequency theory (in pitch perception)
For low pitch, the rate of action potentials signals frequency of sound wave (up to 100 Hz)
Describe the volley theory (pitch perception)
Combinations of action potentials slights de-synchronised collectively signals the frequency of sound wave (100-5000 Hz)
Describe conductive hearing loss
Problems in the outer/middle ear:
-amplification of sounds (ie hearing aids) can be helpful
Describe sensorineural hearing loss
Problems in inner ear, auditory nerve and auditory cortex can be more complex
-cochlear implants
what’re some Causes of hearing loss
Genetic/congenital
Disease/injury
Noise induced
Medications/substances
Age related
Basics of smell and taste
Olfaction (smell) and Gustation (taste) are “chemical senses”.
Work together to enhance liking or disliking of some foods
Evolutionarily beneficial - critical role in sampling food before swallowing
Olfaction
Olfactory receptors code for one odour
-lock and key analogy
Humans can identify ~2000-4000 odours
Some people have better olfaction than others (young people, females, non smokers)
We adapt rapidly to smell
-perfume, our own body odours
Gustation
Sweet, sour, bitter, salty
- now also umami (Japanese name for miso soup type taste)
- some early evidence for fatty acid receptors
But, taste is only a small part of the eating experience
What is the “tongue map myth”?
The myth that certain parts of the tongue are responsible for different types of flavour
Olfactory and gustatory perception
Smell and taste converge on parts of the limbic system (orbitofrontal cortex, amygdala)
Strong link between smell, taste and emotion
Somatosensory system
Specialised receptors within the skin detect physical stimuli from the external environment
There are 3 classes of skin receptors:
- pressure: “mechanoreceptors”
- temperature: “thermoreceptors”
- pain: “nociceptors”
What is the phantom limb illusion?
Phantom limb pain of amputees can be relieved with a mirror box
What is congenital pain insensitivity?
- issac brown was born with a congenital insensitivity to pain
- Isaacs parents had to teach him to identify injuries
What is proprioception? - body position
Basically the awareness that we exist and move within space
Kinaesthetic sense
Proprioceptors (stretch and force) are located in the joints, muscles, and tendons providing feedback to the brain.
Vestibular system - balance
Vestibular control
-balance:
- inner ear: semicircular canals and otoliths
- information sent to the brain stem and cerebellum to cooordinate/ajust eye, head and body movements.
Basics of Perception
Organisation of sensations into meaningful units that can then be interpreted by the brain
An active process by which the brain selects, organised and interprets sensory information
There’s no “one to one” correspondence between the sensory stimuli and the perception (percept)
what are some principles of perceptual organisation:
-Top down and bottom up processing
perceptual sets/context (generally occur simultaneously)
- Perceptual constancy
- Gestalt principles
- Motion perception
- Depth or distance perception
Gestalt principles
Gestalt = whole
Theory developed by German psychologists in 1920s
‘Gestalt principles’ or rules describe how visual elements are organised into groups or unified wholes
Whole is greater than the sum of its parts
Key Gestalt principles:
-simplicity, proximity, similarity, continuation, closure, symmetry, figure ground
Motion perception
Visual system is organised to detect motion
- some cells in the retina are sensitive to motion
- neurons (feature detectors) in visual cortex respond to motion
Two ways of detecting movement
- A: eye is stationary as object moves on the retina
- B: eye moves to maintain object at same place on the retina
Depth (or distance) perception
The organisation or perception into three dimensions
Two kinds of visual cues enable us to judge depth and distance
Binocular cues: visual input from two eyes
Monocular cues: only one eye provides visual input
