14 Theory of Signal Detection
Physiologist
生理學家
Father of Experimental
Wilhelm Wundt (1832-1920)
研究物理量對人的改變
Physiologist
Ernst Weber (1840-1900)
研究多少的物理量人才能偵測到改變
Just-noticeable-difference (△I)
constant proportion (k)
initial stimulus magnitude (I)
△I / I = k
Father
Gustav Fechner (1801-1887)
Study of the relationship
between stimulus intensity
and subjective experience
(detection) of the stimulus
Psychophysical Law
心理物理學定
Steven’s
log Y = k log(I)
Loudness 0.3 Both ears
intensity增加10 dB
你就會感覺到兩倍大聲
Theory of Signal Detection, TSD
訊號偵測理論
Detectability (可探測性) vs.
Response Bias (反應偏差)
The difference between what you hear and
what you say you hear.
Sonar (聲吶) & Radar (雷達)
Cold War Years
β = Response Bias
d' = Detectability
d' = Z(FA) - Z(HIT)
effect
stimulus strength ↑ → HR ↑, FA ↑
noise ↑ → curves wider → curves overlap ↑
Receiver Operating Characteristic, ROC
describes all possible combinations of hit and false alarm rates yielding a given d’.
criterion ↑ → FA & HR ↓
criterion ↓ → FA & HR ↑
Computation
if Rate>0.5
Z = -Z (←1-Rate)
Z score