Midterm 1 Flashcards
(190 cards)
What is phenomenology?
focuses on the expereince of stimulus
person expereinces stimulus than describes it
What are some cons of phenomenology?
poor control over the stimulus, cannot easily repeat observations, relies on introspective reports
What role does phenomenology have?
useful if followed up by systematic controlled expereiments to verify
What is psychophysics?
The study of the relationship between the physical stimulus
and our perception of that stimulus
Who developed the original set of psychophysical methods?
Gustav Fechner
What is the absolute threshold?
smallest amount of energy needed to
detect a stimulus
What would a graph of the idealized absolute thershold look like?
no one would notice a stimulus and then once the threshold is reached everyone would detect it
What is the method of adjustment?
psychophysics
The observer ‘adjusts’ the stimulus intensity until the stimulus is
detectable
What is a pro and a con of the method of adustment?
PRO: fast and easy for observer to perform
CON: open to bias, more variable than other methods
What is the method of limits?
uses ascending and descending series, alternates between gradually increasing or decreasing the intensity of a stimulus until a participant can just detect it
What is the simple staircase procedure (method limits)?
trials begin above/below threshold, continues to increase/decrease stimulus until observer changes answer, direction is reversed, and so on
What is an interleaved staircase procedure?
two staircases at the same time, one starts high the other starts low
What is the method of constant stimuli?
uses range of values that brakcet threshold presented in a random order
What is the point of subjective equality?
PSE (50%)
intensity at which you cannot differentiate between the stimulus
and noise, or when you cannot tell the
difference between two stimuli
What does a steep slope on a psychometric function mean?
high precision (low variability)
What is the purpose of signal detection theory?
used to
assess thresholds independently of the response criteria
What are the 4 responses in signal detection theory?
hit (correct), miss (no when stimulus), false alarm, correct rejection
In signal detection theory every trial is (equation)?
signal + noise (S+N)
What does liberal criterion look like on the distribution?
N results in high probability of false alarms, S+N result in high hits
What does conservative criterion look like on the distroibution?
N presents few false alarms, S+N results in low hits
A persons sensitivty is indicated by what on probability distribution?
the distance (d’) between the peaks of N and S+N distributions
How can we use signal detection theory experimentally?
measure the ROC curve by manipulating the reward/cost of
hits and false alarms
measure hits and false alarm rates assuming a neutral
criterion. This provides one point on the ROC curve, a
mathematical formula can be used to compute
What is another name for difference threshold?
DL (differece limen), just noticable difference (JND)
What is Weber’s Law?
JND/S = K
K is a constant
as stimulus size increases so does JND