PSYC 4031 : Sensation And Perception Test 1 Most Notes
Document Summary
Three classical methods of psychophysics that we have examined have a common goal: locating a threshold. Signal detection theory - argues that the thresholds obtained by classical psychophysical methods are composites of two separate processes: 1) the observer"s sensitivity to the stimulus and: the observer"s decision-making strategy or criterion. Signal - where a weak physical stimulus is present. Noise - where no physical stimulus is present, only background noise. The physical stimulus alone is not sufficient to determine perception - mental factors are also critical. (s/n) signal to noise ratio. Receivers often report sensitivity in terms of s/n ratio, with higher numbers indicating increased sensitivity. When you expect a stimulus, you shift your criterion. Criterion - willingness to say that you detect a stimulus. Signal + noise - a set of trials that include both the signal that one is supposed to detect as well as the background noise.
