The Signal Detection Test Thesis


Page 1 of 1 PSY3002_Cognitive Lab © 2009 South University


The Signal Detection Test: Practical Applications SDT can be used in conditions where people need to determine the presence or absence of certain signals. It has widespread applications ranging from detecting auditory tones in a research laboratory to reading X-rays in a medical laboratory. One important measure in SDT is that of response bias. Depending on the conditions, people might be willing to report the presence of a stimulus even if they’re not sure about it. Other situations might require a person to be more conservative—reporting hits only if they’re absolutely sure that a signal is present.

Response bias can be manipulated by:

• Payoffs

• Motivation

• Sensitivity Levels

Payoffs: For instance, radiologists might have a bias to report tumors even when they are not absolutely sure that the target spot is a tumor. This approach may cause them to report false alarms; however, underreporting tumors could result in higher rates of patient deaths and potential lawsuits. Therefore, a radiologist is motivated to report tumors.

Motivation: For instance, a basic hearing assessment test requires patients to indicate if they heard a tone or not. Tones are usually present in about half the trials. Some patients could be motivated to show that they have normal hearing and report that they hear a tone on every trial.

Sensitivity Levels: For instance, airport security screeners at security checkpoints are expected to constantly be alert in detecting weapons concealed in carry-on baggage. Since people do not frequently carry weapons in their bags and screeners do not often detect concealed weapons in passengers’ baggage, their sensitivity to detect weapons decreases.