Wize University Psychology Textbook > Sensation & Perception
Signal Detection Theory
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Signal Detection Theory
Most of the time, sensation and perception are not completely clear cut.
Signal detection theory explains how we make decisions about stimuli in ambiguous situations.
Signal - the thing we are interested in detecting
Example: A knock at the door
Noise - all of the other interfering information that can obscure the signal.
Example: Noise from the tv, people walking down the hallway, ambient noise from appliances
Our decision about whether a signal is present or absent is a function of the strength of the stimulus, the strength of the noise, past experience, and expectations.
Criterion - point at which signal is strong enough for us to say the stimulus is present.
Criterion can be shifted by many things outside of pure sensory processes:
- Consequences of making a mistake (miss or false alarm)
- Past experience
- Expectations, base rates, likelihoods
Practice: Signal Detection Theory
A researcher is designing a signal detection experiment. She decides to tell a participant that she will lose a dollar for every miss she has, but she will not receive any reward for hits. In this instance, the researcher's manipulation of situational factors, such as the cost for a miss, will likely have an impact on the participant's:
Practice: Signal Detection Theory
When a subject detects a signal that is not actually present, we call it a: