psychophysics and psychoacoustics Flashcards
thresholds
finding the limits of what can be perceived
not absolute
scaling
measuring private experience, your own qualitative experience
signal detection theory
measuring difficult decisions
ie/ seeing smt that might be cancer, but you are not 100 percent sure
makes a distinction between an observer’s ability to perceive a signal and their willingness to report it
sensory neuroscience
the biology of sensation and perception
neuroimaging
an image of the mind
ie/ binocular rivalry, showing two different images to your eyes and they compete to dominate your eye
what is psychophysics
the study of the relation between the physical stimulus and the psychological (experience we have, subjective) sensations - how these things work together
mental life and physical world. relationship between mind and body using mathematics
gustav fechner
1801-1887
invented psychophysics and could be considered the true founder of experimental psychology
what is the content of psychophysics
detection - tell smt is out there
discrimination - difference between stimuli
identification
scaling
detection
determining the minimum amount of a particular stimulus that is required for the individual to say a stimulus is present
absolute threshold
the stimulus energy above which the stimulus is detectable
Method of constant stimuli
fixed set of stimuli,ranging from rarely to almost always perceivable, are choseen in advance.
each presented one at a time, many times in random order.
each intensity, multiple times, in a random order.
create many stimuli with different intensities, in order to find the tiniest intensity that can be detected.
The problem of background noice
Variability-and nerons firing
internal and external sources
All of our sensory systems have evolved to account for the “spontaneous firing or resting rate” of our normally functioning neurons-meaning that our sensory systems are going to be more or less sensitive at different times
Internal sources
You can always hear something even in the quitest of places
need to detect presence of internal noise.
external sources
unintentional
sometimes they are not a problem
problem when stimuli magnitude is greater
method of limits
the magnitude of a stimulus is varied incrementally until the participant respond differently
more efficient if the experiment begins with the same stimuli of varied intensity
when they can hear a tone, tones presented in increasing intensity (when can you hear tone) or vice versa (when no longer hear tone)
change stimulus until person changes their response - transition from change in response in their threshold
ascending trials - no -> yes
descending trials - yes -> no
errors:
error of preservation
error of anticipation
controlling for errors
method of adjustment
similar to method of limits, but the participant control the stimulus directly
ie/ like adjusting the radio volume
to study how we perceive things we need to study
the properties of the physical world
the properties of our sensory system - convert neural impulse to something we can interpret
the higher - level processing which allows us to interpret the symbolic signals
Sensitivity
a value that defines the ease with which an observer can tell the difference between the presence and absence of a stimulus or the difference between two stimuli
how easy can you pick up signals(or difference) in the world.
Criterion
an internal threshold that is set by the observer
If the internal response(in nervous system) is above criterion< the observer gives one response.
Below criterion, the observer gives another response.
Discriminability
How well an observer can seperate the presence of a signal from its absence
measured by d’ (discriminability index, also called sensitivity)
Receiver Operating Characteristic(ROC)
plot false alarms on x-axis against hits on y-axis
Just-noticeable difference(JND)
the smallest detectable difference between two stimuli, or the minimum change that can be correctly judged as different from a reference stimulus(also known as difference threshold)
half of the interval of uncertainty
changed in a systematic way
webers law
the smallest change in a stimulus that can be detected is a constant proportion of the stimulus level.
delta I/I =k - fechner found a way to describe the relationship between mind and matter
Sound
The physical stimulus for the ear: vibratory pressure waves
Sounds cause molecules in the objects medium(usually air)
Vibrations cause pressure changes(waves)
Sound becomes less prominent as we move farther from the source
Sound waves move faster in denser substances