Flashcards in Week 1 Deck (14):
What is psychophysics?
A study of the quantifiable relationship between a stimulus and perception.
The minimum stimulus magnitude at which a stimulus can be reliably detected is know as the _____?
Describe the procedure involved with a method of constant stimuli?
1. Construct a set of stimuli with a range of magnitudes.
2. Present stimuli in random order
3. Plot the results
4. Threshold is taken as the magnitude at which the stimuli is detected at a pre-determined proportion of the time. (e.g. 50%)
Describe some ads and disads of the method of constant stimuli.
Ads- allows shape of psychometric function to be established, provides an accurate estimate of threshold.
DisAds- time consuming, requires pre-testing to establish threshold region, wastes trials, difficult to measure changes over time.
Describe method of limits protocol.
Asc or desc, presents stimuli at sub threshold level, increase until the participant can detect. this is the threshold
Describe some ads and disads of the method of limits
Doesn't plot shape of psychometric function. Quicker. Habitual 'yesses' or 'nos' not so accurate, still wastes trials.
Describe the adaptive staircase procedure
staircase run until a reversal is evident. Staircase direction changes. procedure is terminated after a criterion number of reversals.
The mathematical formula for determining what threshold the adaptive staircase is measuring is:
n square root 0.5
The two conditions in Signal Detection Theory are:
Catch Trials, Signal Trials
Activity that stimulates our sensory system and results in a positive response during a catch trial is called:
What does dprime measure in signal detection theory?
The sensitivity, the difference between the noise and signal + noise distribution. Big prime means the experiment is easy - the trial is easy to detect or reject - big distinction.
Why might you use the double adaptive staircase method?
If you suspect there might be strong participant bias - prevents against anticipation
How do you measure d prime?
The difference between correct rejection and hits.