Lecture 4 Flashcards
Sensation
What is sensation?
The process by which info is gathered from environment and transmits to the brain for processing
What is perception?
The process by which the brain interprets and organises this sensation (sensory info).
What is the first principle of sensation and perception?
There is no one-to one correspondence between physical and psychological reality. Measuring this different perception of stimuli is psychophysics.
What is the second principle of sensation and perception?
Both are active processes. Actively involve ourselves in stimulus e.g name spoken and we turn to listen /hear.
What is the third principle of sensation and perception?
Sensation and perception are adaptive e.g smell of yuck food = disgust because we should steer clear.
What is the progress of the sensory system towards perception
- Accessory structure modifies energy
- Receptor will transduce energy
- Sensory info transferred to CNS
- Initial processing in thalamus (except for smell) and relays to cerebral cortex
- Processing in cerebral cortex produces perception
How do we sense the environment with the 5 senses?
- Detecting physical energy (light/colour waves)
- Transduction on the basis of intensity and quality of sensory info
- Intensity: Number of neurons and frequency at which they fire
- Quality : Type of receptor involved, i.e colour, pitch, taste, temp
What are thresholds in sensory systems?
Requiring the minimum amount of energy required to activate system e.g tip toeing cant be heard until intensity increases when they are closer
What is decision making in sensory systems?
Determining which environmental stimuli is meaningful or not e.g dog braking outside at night (no response), however a smashing window may require a decision to evoke response.
Provide an example of level changes in stimulation levels? (sensory systems)
Going from a first attempt squat to a second attempt squat by 10kg.
Why do sensory system tune out redundant information?
For more efficient sensory information processing. Turning down the volume on other stuff.
What is encoding?
Translation of a stimulus’ physical properties into pattern of neural activity that specifically identify those properties.
What is nerve specific energy doctrine?
Stimulation of a particular sensory nerve, provides codes for that one sense. e.g rubbing your eyeball with produce light.
What are the two types of stimulus codes?
Temporal code: changes in the timing of firing of neurons.
Spatial code: provides info about stimulus by identifying location of firing neurons relative to their neighbours.
What is sound?
Repetitive fluctuations in the pressure of a medium e.g air.
Distinguish between vibration and wave
Vibration: Requires an object to produce fluctuations in pressure to create sound.
Wave: Repetitive, rhythmic variation in pressure that spreads in all directions.
How and what are the two dimensions in which a wave form is characterised?
Amplitude: intensity - difference in airpressure from it’s baseline to peak.
Wavelength: Distance from one peak to the next.
Frequency (Hz): Number of complete waveforms/cycles that pass every second.
wavelength and frequency are related - longer wavelength = lower frequency
Psychological dimensions of sound - Loudness
- Amplitude
- Measured in dB
Psychological dimensions of sound - Pitch
- Frequency
- Higher or lower tone
Psychological dimensions of sound - Timbre
- Wave patterns added o the lowest/most fundamental wave frequency
- Depends on specialised neurons
Pinna?
- Crumpled part of outer ear
- Collects and shapes sound down to ear canal
Ear canal
The passage by which transfers sound from pinna to middle ear.
Middle ear
- Tightly stretch membrane known as tympanic membrane (eardrum).
- Vibrations from tympanic membrane transferred to three tiny bones - Malleus (hammer ), incus (anvil) and stapes (stirrup).
Inner Ear
- Bones amplify changes in pressure produced by original sounds focusing vibrations of tympanic membrane of oval window - via semi circular canals. Incl. cochlea.
Components of inner ear;
- Cochlea (transduction)
- Basilar membrane
- Organ of corti
- Hair cells
- Acoustic nerve
What is conduction deafness?
- Middle ear bones fuse (Malleus, incus, stapes) and cannot properly amplify vibrations.
What is nerve deafness?
- Results from damage to acoustic nerve and hair cells.
- Occurs with age or through exposure to loud sounds overtime.
What constitutes visible light on an electromagnetic spectrum?
From just under 400 nanometres to about 750 nanometres
What does light intensity vs light wavelength?
- Intensity refers to how much energy the light contains and determines brightness
- Light wavelength depends on what colour you see, with different wavelength producing sensations of different colours.
What are the major structures of the eye?
- Cornea, Iris, Pupil, Lens, Muscles, Retina, Blind Spot
Psychological dimensions of light (Hue)?
- Colour (besides white, black, grey)
Psychological dimensions of light (Colour saturation?)
- Purity of colour
Psychological dimensions of light (Brightness)?
- Intensity of wavelengths
What is the Trichromatic (Young-Helmhotz) theory?
- Short, medium and long wavelengths -visual elements to the eye, each sensitive to different wavelengths.
Short: Sensitive to blue (440 nm) Medium sensitive to green (510 nm) and Long sensitive to reddish - yellow.
What is the Opponent -Process theory of colour vision?
Colour sensitive elements in eye grouped in pairs that oppose each other. One activates when other is no longer stimulated. Red/Green Blue/Yellow Black/White
- Explains afterimages and complementary colours.
What part of brain are sen information from the olfactory bulb?
- Frontal lobe
- Amyglada
(TRUE/FALSE) - Olfactory bulb sends information through the thalamus.
FALSE
What happens if there is a loss of olfactory sense?
Could indicate certain brain diseases that affect memory and emotion.
What are the taste sensations?
Astringent, Bitter, Sweet, sour, salty, Umami
What is papillae?
Grouped taste buds in mouth and throat
What is the cutaneous sense (intensity of the stimulus) encoded by?
Firing rate of individual neurons and the number of neurons stimulated
What are warm fibres?
Increase their firing rates when temperature changes int he range of 95-115 degrees F. Temperatures above this range are painful and stimulate the cold fibres in efforts to remain homeostatic.
