Lecture Week 1 Flashcards
Define Sensation
- Being able to detect a sensation through your receptors
- Transduce that into electrical energy
- Then process that in the brain
- Becomes a personal experience such as a memory or observation
Define Perception
- Perception is what we do with the stimulation of sensation
- How we interpret sensation and give meaning to input
Define Transduction
- Sensation occurs via transduction
- Converts one energy to another
- Pressure converts to electical energy
- This causes action potentials in the axons
- We percieve the sensation then the brain can recognise the sensation
- Finally the brain takes an action based upon the recognition.
The 7 Steps of the Perceptual Process
- Environmental Process
- Stimulus is transformed into electrical energy
- Receptor processes
- Neural Processing
- Perception
- Recognition
- Action
Sensation is. . .
The stimulus being transformed into electrical energy and going to the brain
Perception is . . .
- Occurs in the higher levels of the brain
- Recognising objects
- Decide to take an action
Sensation and Perception precedes . . .
Everything we do in psychology.
How are sensation and perception received
- Bottom up path to processing
- Move from sensation to perception to cognition
- Some Top Down processing
- Existing Knowledge can influence sensation
- Existing knowledge affects our gaze direction
- In hearing, cochlear is finely tuned to hear and amplify sounds that we have become conditioned to hear.
eg: hearing your name in a crowd.
Psychophysics
- The science of defining quantitative relationships between physical and psychological events
- How we measure perception objectively?
- How can we be sure that we all see the colour green in the same way
Qualia
- a quality or property as perceived or experienced by a person
Absolute Threshold
- The minumum amount of stimulus necesary to perceive a sensation.
- needs to be perceived 50% of the time
Method of Constant Stimuli
- most commonly used to measure absolute threshold
- give participants a range of stimuli one at a time
- vary randomly between not perceivable and always perceivable
Method of Limits
- Present the stimulus incrementally until the participant can detect it
- Usually presented from least perceivable tone to always perceivable tone.
- Often there is an overshoot, it will take a participant a while to hear it unlike the other methods that are used
Method of Adjustment
- Simmilar to Method of Limits except participants have control of the dial
- They can adjust the sound as they hear or do not hear the stimulus tone
Measuring Perception
Participant Detects a change in stimulus
- Participants given a weight to lift a number of times
- The weight is then changed without the participant noticing
- Given another weight,
- at what weight difference can the participant detect the change.
- What is the minimum weight difference that can be detected
Just Noticeable Difference (JND)
- The smallest detectable difference between two different stimuli
Weber’s Law
- Found the JND is a constant fraction of the comparison stimulus.
- In weight the JND is 1/40 of the comparison weight.
- JND = 1/40*Weight
Fechner’s Law
- Found Weber’s Law doesn’t work for High and low intensities
- 1/40 Law doesn’t hold true at these ends of the spectum
- Fechner came up with a logarithmic rule
- Instead of a straight line relationship in Weber’s Law, the JND increases proportionally to the intensity of the stimulus
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Steven’s Power Law
- Fechner’s logarithmic calculation of the proportional JND doesn’t hold true for all modalities
- If we double the intensity of a light does it look twice as bright?
- Looking for a qualitative measure for a subjective experience of the magnitude of the stimulation
- The magnitude of the subjective sensation is in proportion with the stimulus magnitude offered to participant
- Participants subjective experience of changes in the magnitude of sensation differs in the modality we are talking about.
Cross-Modality Matching
- The ability to match the intensities of sensations that come from different sensory modalities.
- Can our different sensations be cross matched?
- can we quantify; does taste have a value of sound
- Helps to explore whether or not we have the same experiences.
- Is sensation a universal or unique experience
Signal Detection Theory
- There are four options possible when a stimulus is present
- Detection of a stimulus depends on the participants sensitivity to the stimulus and the participants response criterion
- Depends on
- presence of a signal
- expectation of signal.
- Response criterion
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Criterion
- A standard of judgement or criticism
- An established rule or principle for testing anything
(d) prime value
- Look at the proportion of hits & correct rejections vs miss & false alarms to calculate (d) prime value
- The larger the (d) prime the more certain the participant is that the signal is actually there.
Odourant
- A molecule capable of being translated into the perception of smell by the nervous system
- Must be small enough, be able to fly thought the air and be water repellent
Odour
Once an odourant is transduced into a sensation of smell by the nose it is now called an odour
Olfactory System
- Detects molecules in the air and allows for sense of smell
- Converts an odourant into an odour
Olfactory Cleft
- Narrow space at the back of the nose
- About 2 ¾ inches above the nostril
- Contains the Olfactory epithelium
Olfactory Epithelium
- The seat of transduction
- Where Olfactory Sensory Neurons are located
- Odour molecules are transduced into sense of stimulation or the odour
- Contains around 5-10 Million OSNs
- OSNs regenerate every 2 months or so
Olfactory Bulbs
- Receptor cells send transduce odourant into neural firing to olfactory bulbs
- Olfactory Bulbs are an extension to the brain that receive the axons from OSNs
- About the size of a blueberry
- Sit just above the olfactory epithelium
Turbinates
- Ridges inside the nose that add turbulence to the air before it reaches the olfactory cleft
- Puffs air right up into the olfactory cleft so it can stick to the mucous patch of the olfactory epithelium
- Olfaction begins when the odourant travels to the olfactory cleft and then activates transduction in the OSNs
Glomerulus
- Collects activation from OSNs
- Gathers and combines all that electrical information and sends it on to the brain.
- Happens in 400 ms to travel to the brain
- In terms of sensory activation this is considered slow
- Olfactory bulb sends information to the Primary Olfactory Cortex
Primary Olfactory Cortex
- Receives electrical energy from olfactory bulb
- Located in the Limbic System
- Same area as the amygdala and the hippocampus
- Considered part of the basic brain structures from and evolutionary perspective
- Primary olfactory cortex projects to the Orbitofrontal Cortex both directly and via the amygdala
Tip of the Nose Phenomena
- Linguistic Processing is highley disconnected from Olfactory experience
- We do not have language to appropriatley describe smells
Smells and Memory
- Smell is durble and stable over the long term
- This is not so for other senses
- Smell is a more emotionally intense memory inducement
Pheromones
- chemicals emitted by one member of a species to attract an opposite member of that species
- Androstadienone is an endogenous steroid that has been attributing potent pheromone activity in Humans
Androstadienone
- Chemical wih potent pheromone like activity in humans
- Has been added to male scents claiming to make the wearer more sexually attractive to women
- Studies demonstrate that this does not work as it is a chemical mostly attrubited to pigs not humans
Chemosignals
- Chemicals released by humans
- Detectable by the olfactory system
- Have an effect on mood, behaviour, hormonals status and possibly sexual arousal of other humans