Chapter 1 Flashcards
Introduction to Sensation and Perception
sensation
the process bu which a receptor (i.e. sensory organs) detects stimuli and creates a process of neural activity
Perception
the act of giving meaning to a detected sensation
perception _______ sensation, but not __:___
interprets; 1:1
while stimuli in the world follows the laws of physics, our _________ of them does not
perception
t/f: our visual system is great at detecting large changes in our immediate environment
false; monkey business video!
t/f: our sensory systems are relatively independent
false; McGurk Effect
McGurk Effect
visual and auditory systems interacting, video audio saying “ba” but when visual shows someone mouthing “fa” you hear “fa” even when audio doesn’t change
t/f: our perceptual system can cause us to perceive things that aren’t really there
true; ex) seeing Jesus in toast because you want to
t/f: our perceptual abilities are innate and don’t need to be learned
bit of both!
hard wired to see, hear, etc. but specific structures support perception
ex) visual cortex = vision, but in blind people this part of the brain can respond to auditory/tactile information
even with neuroimaging, we don’t really get to see….
your mental perception and have to make inferences and theories instead
_______________ is critical for understanding how we perceive the world
scientific approach
5 ways we measure sensation/perception
thresholds
scales
signal detection
cellular/neuronal neuroscience
systems neuroscience
psychophysics
invented byt Fechner
the science of defining quantitative relationships between physical and psychological/subjective events
showed that the mind can be studied and quantified
dualism
the mind exists separately from the material world and thus is not a pure representation of it / 1:1
thresholds
generally the minimum difference between stimuli needed to be detected as different
two point threshold
within the realm of touch, this is the minimum distance at which two separate sensations can be distinguished
use compass-like device to test this, different parts of the body have more or less sensitivitiesjust
noticeable difference (JND)
the smallest detectable difference between two stimuli, or the minimum change in a stimulus that can be correctly judged as different from a reference stimulus
i.e. difference threshold
example of JND
how much can you cut back on salt in a recipe before you notice the difference in taste
absolute threshold
minimum amount of stimulation necessary for a person to detect a stimulus 50% of the time
why does absolute threshold have 50% of the time rather than 100%
to account for other factors as it is impossible to have perfect conditions when testing psychology
key point about thresholds is
that they are quantifiable measurements of out perceptual abilities
are thresholds always the same?
NO!
Weber’s Law
the principle describing the proportional relationship between stimulus and resulting sensation that says the JND is a constant fraction of the comparison
larger stimulus values have larger JNDs and smaller stimulus values have smaller JNDs
Weber’s law example
if you are already wet, it will take more rain drops to notice it is raining than if you are dry
Fechner’s law
formalized weber’s law into mathematical terms, such that magnitude of subjective sensation increases proportionally to the logarithm of the stimulus intensity
threshold method of constant stimuli
test many stimuli, one at a time, across range including barely perceptible to always perceptible
ex. eye test at doctors
threshold method of limits
vary the magnitude of a stimulus (or difference between two) until participant notices
ex. experimenter turns on stimulus, changes it until participant realizes change
threshold method of adjustments
same as method of limits but instead of the experimenter altering the stimuli, the participant alters it themselves
scales
measure the “strength” of your sensation, rather than threshold of detection
t/f: all sensations have the same scale
false
magnitude estimation
give participants a sensation and have them rate its strength, can be freeform or give starting baseline
ex) when a doctor asks to rate your pain on a scale of 1-10, a baseline could be a headache
Steven’s power law
scale based on power/exponent equation
on a scaling methods chart in relation to steven’s power law, which causes the most stimulus energy?
brightness
sweetness
comparison of lines
electric shock
electric shock
2 similarities between steven’s power scale and fechner’s log scale
both make broad assumptions about the “fit” of data to their metrics and about the scales they work on
both are only approximations of data and turn out to not really be “laws” (don’t apply directly to human experiences)
main takeaways from thresholds and scales
- people’s internal perception can be modeled
- sensation is proportional to other parameters
Signal detection theory (SDT)
ability to detect a signal amongst noise
SDT accounts for
amount of noise
discriminability of the signal
biases in the person’s response patterns
criterion
value that is somehow determined by observer, can change depending on situation
i.e. your threshold for deciding if you detected a sensation
hit
there was a sensation and you detected it
ex) your phone buzzed and you checked it
correct rejection
there was no sensation and you didn’t detect it
ex) your phone did not buzz and you did not check it
false alarm
there was no sensation but you detected one
ex) your phone did not buzz but you checked it
miss
there was a sensation but you didn’t detect it
ex) your phone did buzz but you did not check it
sensitivity in SDT
how discriminable the target is from the noise
distance between two peaks in the graph (closer together = less sensitivity and vice versa)
receiver operating characteristic (ROC) curves
demonstrate both the sensitivity and criterion in one line
plots hits and false alarms (both yes responses)
with greater sensitivity, curve moves closer to top left corner, criterion is represented by point on the curve
transduction
physical stimuli being converted to biochemical/electrical signals in our nervous system
parts of the neruon
dendrites - receiving info from other neurons
axon - signals go down
axon terminals - carry signal to other neuron’s dendrites
neurons generally transmit signals via ____________ at the _______
neurotransmitters; synapse
synapse
space between two neurons
pre-synaptic neuron _______ neurotransmitters into the synapse while post-synaptic neuron has ______
releases; receptors
neurotransmitters trigger an electrical shift in the post-synaptic neuron, leading to the neuron “firing” an ___ _______
action potentials
neurons fire in an ___ __ ____ fasion for each action potential/spike
all-or-none
how to tell how excited the neuron is during action potential
the number of spikes per second
each action potential starts where and ends where?
starts: near cell body of neuron
goes down axon
ends: axon terminal
what neurotransmitters does the electrochemical process involve?
Na+ (sodium) and K+ (potassium) ions
3 steps of depolarization in neurons to send signals
- Na+ rushes in
- inflow of Na+ depolarizes the membrane to carry the signal
- neuron recovers by quickly sending K+ out of the cell to get back to resting potential
neuronal signals often compete, having excitatory and inhibitory signals, meaning
excitatory - increase in action potential
inhibitory - decrease in action potential
2 types of nerves and what they control
afferent (send information to the brain), control sensory function
efferent (send information from the brain), control motor function
electroencephalography (EEG)
electrodes on scalp to directly measure the electrical activity generated by neural firing of a large population of neurons
can assess ERPs
event-related potentials (ERP)
change in EEG signal as a result of an event, such as sensation
EEGs have excellent _________ and poor __________
temporal resolution; spatial resolution
Magnetic Resonance Imaging (MRI) - structural
uses magnets to assess the atomic structure of tissue
no radiation but dangerous if metals brought in
MRI - functional / fMRI
tracks blood oxygen level-dependent (BOLD) signal, which is the ratio of oxygenated to deoxygenated hemoglobin that shifts in response to neural activity (i.e. when neurons fire more, they require more oxygen)
an indirect measure of brain activity
fMRI has excellent ________ but poor __________
spatial resolution; temporal resolution
opposite of EEG
PET and MEG
PET: similar to fMRI but based on metabolism of brain cells
MEG: changes in magnetic activity across populations of many neurons in the brain
Velma is searching for clues with Scooby and the Gang, when she, as always, breaks her glasses. According to signal detection theory, what MUST have changed with regards to her vision by losing access to her glasses?
A) Her criterion becomes more lax, and she is more likely to accept stimuli as real even if they are not.
B) Her criterion becomes more strict, and she is less likely to accept stimuli as real, even if they really are.
C) Her sensitivity increases, as she is more able to distinguish between signal and noise
D) Her sensitivity decreases, as she is less able to distinguish between signal and noise
D) Her sensitivity decreases, as she is less able to distinguish between signal and noise
Bjorn is expecting a phone call. After repeatedly accidentally checking his phone, he has started using a stricter criterion, wanting to avoid false alarms.
Which of the following statements reflects what may also happen now that he has a stricter criterion?
A) He is more likely to false alarm to noise, accepting as signal.
B) He is less likely to detect a real call, missing it as noise.
C) He is more likely to detect a real call, discriminating it from noise.
D) He is less likely to correctly reject noise, mistaking it as a phone call.
B) He is less likely to detect a real call, missing it as noise
Which statement is true about EEG:
A) It is a direct measure that has good spatial resolution
B) It is an indirect measure that has good spatial resolution
C) It is a direct measure that has good temporal resolution
D) It is an indirect measure that has good temporal
resolution
C) It is a direct measure that has good temporal resolution
