Signal Detection Theory Overview

Study Notes

Signal Detection Theory

Predicts detection of faint stimuli (signal) amidst background noise.
Detection influenced by experience, expectations, motivation, and alertness.
No absolute threshold exists; detection varies with context and observer.

Practical Applications

Used in TSA procedures at airports to identify potential threats.
Employed by doctors to interpret EKGs for heart conditions.
Relevant in aviation, with pilots detecting signals during flight.

Key Terminology

Signal: The desired stimulus that the observer attempts to identify.
Noise: Both internal (e.g., biases, distractions) and external (e.g., environmental sounds) interference affecting detection.
Criterion: An observer's personal internal threshold for determining signal presence; can adjust based on context and individual differences.

Decision Outcomes

HIT: Signal correctly detected; observer answers "yes" when signal is present.
FALSE ALARM: Observer mistakenly identifies a signal when none is present.
MISS: Signal present but not detected; observer answers "no."
CORRECT REJECTION: No signal detected and accurately reported; observer answers "no" when signal is absent.

Sensitivity and Measurement

Sensitivity (d' prime): Reflects the observer's ability to detect signals; higher sensitivity indicates clearer discrimination between signal and noise.
Greater gap between d' prime thresholds indicates a higher sensitivity due to larger differences in noise.

ROC Curve

Graphically represents an observer's responses in a signal detection experiment.
Visual tool for analyzing trade-offs between HIT rates and FALSE ALARM rates.

Influencing Factors

Sensitivity Factors:
- Level of background noise affects detection capacity.
- Strength of the stimulus plays a role in recognizability.
- Redundancy within a stimulus can enhance detection rates.
Criterion Factors:
- Observer's expertise impacts judgment frequency and accuracy.
- A high propensity to say "yes" increases likelihood of identifying signals.
- Attention levels and motivation directly influence detection effectiveness.

Description

Explore the fundamental concepts of Signal Detection Theory through flashcards. This quiz provides definitions and real-life examples, helping you understand how we detect faint signals against background noise. Perfect for students and professionals in psychology and related fields.