Signal Detection Theory and Psychophysics - Andrei Gorea

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SDT: THE STANDARD MODELOptimal criteria“One very desirable objective, were it possible, would be to maximize p(S|s) whileminimizing p(S|n). A (…) weaker, but feasible, objective is to maximize the quantity{p(S|s) – p(S|n)}where is a constant, > 0. This is a reasonable goal, since it is achieved whenwhen p(S|s) is large <strong>and</strong> p(S|n) is small. The parameter establishes the relativeimportance of these two objectives in the sense that when p(S|s) is increased by anamount , then p(S|n) should increase by no more than / for the change to bedesirable.” (Green & Swets, 1966, p 20)The optimal given payoffs isβ opt =V CR + V FA p(n)V H + V omiss p(s)Where V is the value of the payoffs. When the payoffs (gains & costs) are balanced,the eq. above reduces toβ opt = p(n)p(s)
Measured vs. Optimal criterion ()Observers are close tooptimal for p(S) = p(N) butbecome more <strong>and</strong> moresuboptimal with theincreasing differencebetween p(S) & p(N)Green & Swets (1966)
Page 1 and 2: THEORIE DE LA DETECTION DU SIGNALLa
Page 4 and 5: PhysicalWorldSensoryProcessesInfere
Page 6 and 7: z-ScoreOu « score normal » ou «
Page 8 and 9: P(z)p N (z=c)SIGNAL DETECTION THEOR
Page 10 and 11: Criterion settingObservers set a cr
Page 14: z(FA)1 - p > .5p < .51 - p < .5p >
Page 17 and 18: P(zpHReceiving Operating Characteri
Page 19 and 20: pHP(z)ROC & the Rating experimentOU
Page 21 and 22: PROBABABILITÉd’ with unequal var
Page 23 and 24: d’ with unequal varianceszH210-1-
Page 25 and 26: HIGH-THRESHOLD THEORY*The HTT propo
Page 27 and 28: P(z)pHP(z)pHIn the rest of thedecis
Page 29 and 30: RRRResponsed’TRANSDUCTION & THRES
Page 31 and 32: RRResponsed’TRANSDUCTION & THRESH
Page 33 and 34: LA RELATION ENTRE Y/N & 2AFC1 20 SA
Page 35 and 36: P(z)P(z)P(z)Reasons for “invisibi
Page 37 and 38: P(z)% YESCRITERIONThe response crit
Page 39 and 40: CHANNELS, NOISEandSIGNAL DETECTION
Page 41 and 42: RESPONSE NORMALIZATIONNormalization
Page 43 and 44: RESPONSE (e.g. s/s)CHANNELS & RESPO
Page 45 and 46: RR = kIlog (I )RTRANSDUCTIONR kIs
Page 47 and 48: RR = log(I)log (I )RTRANSDUCTIONR
Page 51: Temps. RéactionTemps. RéactionTre
Page 54: Temps. RéactionTemps. RéactionTem

Signal Detection Theory and Psychophysics - Andrei Gorea

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