University:
University of California, Berkeley
Course:
PSYCH N1 | General Psychology
Academic year:

2020
Views:

475

Pages:

18
Author:

5CelestialChronicle

Signal-Detection Theory Green & Swets (1966), after Tanner & Swets (1954) • Discriminate between “Signal” and “Noise” • Components of Decision – Sensitivity (Information) – d’ – Bias (Criterion) – β • Expectation • Motivation The Signal Detection Paradigm Green & Swets (1966) Signal On Off (Catch Trials) “Yes” HIT FALSE ALARM “No” MISS Correct Rejection Response An Observer with High Sensitivity Hit Rate = 100%; False Alarm Rate = 0% Stimulus Response On Off “Yes” 50% 0% 50% “No” 0% 50% 50% 50% 50% An Observer with Less Sensitivity Hit Rate = 80%; False Alarm Rate = 0% Stimulus Response On Off “Yes” 40% 0% 40% “No” 10% 50% 60% 50% 50% “Liberal” Bias toward Yes Hit Rate = 80%; False Alarm Rate = 80% Stimulus Response On Off “Yes” 40% 40% 80% “No” 10% 10% 20% 50% 50% “Conservative” Bias toward No Hit Rate = 30%; False Alarm Rate = 30% Stimulus Response On Off “Yes” 15% 15% 30% “No” 35% 35% 70% 50% 50% Sensitivity + “Liberal” Bias Hit Rate = 80%; False Alarm Rate = 40% Stimulus Response On Off “Yes” 40% 20% 60% “No” 10% 30% 40% 50% 50% Sensitivity + “Conservative” Bias Hit Rate = 50%; False Alarm Rate = 10% Stimulus Response On Off “Yes” 25% 5% 30% “No” 25% 45% 70% 50% 50% Inducing Liberal Response Bias by Decreasing Catch Trials Stimulus Response On Off “Yes” 52% 18% 70% “No” 18% 12% 30% 70% 30% 100% Inducing Conservative Response Bias by Increasing Catch Trials Stimulus Response On Off “Yes” 18% 12% 30% “No” 12% 58% 70% 30% 70% 100% A Balanced Payoff Matrix Stimulus Response On Off “Yes” +25¢ -25¢ 0 “No” -25¢ +25¢ 0 0 0 A Payoff Matrix Inducing “Liberal” Bias Stimulus Response On Off “Yes” +25¢ -10¢ +15¢ “No” 0¢ 0¢ 0¢ A Payoff Matrix Inducing “Conservative” Bias Stimulus Response On Off “Yes” +10¢ -25¢ -15¢ “No” 0¢ 0¢ 0¢ Signal Detection as Decision Under Uncertainty • Detection not simply a matter of intensity – Judgment Under Uncertainty • Example: Mammography – Family History – Cost/Benefit Analysis • Determinants of Decisions – Expectations – Motives Radiological Society of N.A. Implications of Signal Detection Theory • Detection Not a Simple Matter of Intensity • Passive vs. Active Observer – Expectations, Motives • “Lower” vs. ‘Higher” Mental Processes – Proximity to Physical Stimulus – Ties to Sensory Physiology • Sensory Detection as Judgment – Decision-Making Subliminal Perception? Herbart (1819); Kihlstrom et al. (1992) • Threshold = Limen • Conscious Perception – Conscious Awareness of Distal Stimulus • Subliminal Perception – Change in Experience, Thought, or Action • Attributable to Stimulus – No Conscious Awareness of Stimulus – Perception Implied by Changes in Task Performance Judgment Accuracy at Zero Confidence Peirce & Jastrow (1884) 100 % Correct 80 60 40 Chance 20 0 1.06 1.03 1.02 1.015 Ratio of Weights 1.101 1.005 Scope of Subliminal Perception Kihlstrom et al. (1992) • Methodological Variations – Weak Intensity – Short Duration – “Masking” – Unattended • Not Simple Guessing – Hits > False Alarms • Analytic Limitation – Exaggerated Claims for Subliminal Influence