4) Sensation & Perception Flashcards
Sensation vs Perception
Sensation is the stimulation of sense organs
Perception is the mental representation after selecting / organizing / identifying / interpreting sensory input
Transduction
process where sensors convert physical signals to neural signals
Sensory Adaptation
gradual decline in sensitivity when stimulated long time
How is sensory adaptation different from habituation?
can’t choose to pay attention to how our senses were before the decline in sensitivity
For habituation, brain filters out unnecessary info but we could pay attention to it if we wanted to
When we first jump into a swimming pool, it feels cold. After 10 minutes, it doesn’t feel cold anymore. This is an example of
sensory adaptation
describe the role of attention
flexible attention is important for survival & well-being
gotta pay attention in order to encode
Information we filtered out is still being processed even if we aren’t aware
Selective Attention vs Inattentional Blindness
Selective attention
- Focus on specific things by choosing one sensory channel & tuning out others
- RAS and forebrain control this by activating regions in cerebral cortex
Typically leads to
Inattentional Blindness
- Fail to detect smt that’s right in front of you cuz too busy focusing on smt else
- change blindness is failing to detect obvious changes in environment
Filter theory of attention
like a bottleneck that info goes through
- pay attention to important stuff
Cocktail party effect
Ability to pick out important message (like our name) in random crowdy convos
Shows that our filter isn’t just on & off, brain is ready to act when it senses smt significant
Bottom up processing
starting with perception of raw stimuli, then synthesizing into smt meaningful
Top down processing
Start with our knowledge and expectations, imposing on raw stimuli
ex/ perceptual constancy, perceptual set
Perceptual set
when our expectation influence our perception
an example of top down processing
Parallel processing
ability to attend to many senses at a time
What is the binding problem?
Things we perceive are processed and stored by diff regions in the brain
How does the brain put them all together?
May be due to rapid & coordinated activity
Explains many aspects off perception & attention
Psychophysics
Study of relationship between perceptions & stimuli
absolute threshold, just noticeable difference, etc
Absolute Threshold
lowest level of stimuli needed to be detected 50% of the time, starting from an intensity of 0
Just noticeable difference
Smallest change in intensity of a stimulus that we can detect
NOT starting from 0!
Signal Detection Theory
Stimuli are detected differently under diff conditions
Signal to noise ratio is important:
harder to detect as background noise increase
Response bias
guessing when unsure
Weber’s law
Change in a stimulus that will be just noticeable is a constant ratio of original stimulus
i.e. ratio of diff in intensity : background intensity
Fechner’s Law
Describe relationship between stimulus magnitude and perceived magnitude
Perceived intensity increases proportionally to log of stimulus intensity
Curved graph!
ex/ light bulb
Steven’s Law
Curved graph but says that diff stimuli causes diff changes in perceived intensity
Ppl don’t notice that some days John wears a bit of makeup and other days he doesn’t. Sometimes he puts on a bit more than usual and some ppl (50%) notice. This is an example of
Fechner’s
Steven’s
Just noticeable difference
Absolute threshold
Weber’s
Absolute threshold
Somatosensory System
responds to stimuli applied to skin
sense of touch, pain, temp
All types of nerve endings are spread unevenly throughout body
Mechanoreceptors
Specialized nerve endings on end of sensory nerves in skin
Free nerve endings
More plentiful
Touch vs pain
touch travels faster and is localized more precisely
Where does pain information go?
somatosensory cortex and limbic system
pain
Personal, subjective experience
Influenced by culture, citation, attention, psychological variables
Intricately tied to emotion & cognition
Diff context changes how much pain they actually feel
Doesn’t always come from physical injuries
What are the different types of pain receptors?
Nociceptors
- Mechanical
Respond to excess pressure, deformation, breaks in skin - Thermal
Activated by different levels of temperature - Chemical
Respond to chemicals like spice, venom, irritants, chemicals from changes in tissues - Polymodal
Senses more than one type of pain stimuli
Pain threshold
point when we perceive smt as painful
diff ppl have diff levels due to genetics
What are the functions of pain expressions?
Evolved, not learned!
- Protect from further harm
- Alert others that we are hurt
- May recruit empathy & care
Explain the different theories of pain
Traditional theory (outdated)
- Pain results from transmission of pain signals from injury to brain
- Amount of pain = amount of tissue damage
Gate control theory
- Pain gate in spinal cord that can open and close to modulate pain experience
- psychological factors play important role
Proprioception
body position
Proprioireceptors
Sends info to somatosensory & motor cortex
- Stretch receptors in muscles
- Force receptors in tendons
Gate Control Theory
- Pain gate in spinal cord that can open and close to modulate pain experience
- These factors play important role:
Physical
Open: extent of injury, activity level
Close: meds, counter stimulation like massage
Emotional
Open: anxiety, worry, depression
Close: positive emotions, relaxing
Cognitive
Open: focus on pain, boredom
Close: distraction, concentration, expectations, beliefs
Traditional theory of pain
- outdated!
- Pain results from transmission of pain signals from injury to brain
- Amount of pain = amount of tissue damage
- Can’t explain headaches or phantom limb pain
Vestibular sense
Balance
Cochlea & semicircular canals in ear filled with liquid helps us maintain balance
Sends info to
- parts of brain stem that control eye muscles & reflexes
- cerebellum for controlling body responses
Limited awareness of this sense cuz doesn’t go to cerebral cortex!
Semicircular canals
3 fluidy canals in inner ear responsible for our sense of balance
