## Forced-Choice Recognition Testing

The simplest way to test recognition is to present a stimulus and ask, "Do you recognize this?" Unfortunately, this yes/no method does not take into account the probabilistic nature of recognition. On a true/false quiz, some people are very conservative and will say False if they are not sure of their recognition judgment. They want to avoid false positives, and that is their bias.

What is the drawback of the yes/no method?

Others have a bias toward saying True. Perhaps they want to be agreeable. This can vary between ethnic groups. One pollster found that people of Japanese ancestry had a bias toward saying Yes in opinion polls, perhaps because it was considered more polite, and this threw off the accuracy of results. One person might require only 70% confidence before saying Yes (or True). Another person might say Yes only when he or she is 95% sure. You cannot compare the recognition accuracy of different people unless you know the confidence level each requires for a Yes judgment, and that is something that could change even within an experiment.

One solution is to use the Theory of Signal Detection and present a subject with a range of biasing conditions so the D prime statistic can be calculated. However, a simpler solution is to use a forced-choice method of recognition testing.

In the forced-choice method, what is the target? The distracter?

In a force-choice procedure, subjects are faced with two or more stimuli, only one of which is "old." The old item is called the target item; the other items are called distracters. To give yourself a forced choice recognition test, decide which of the following items was used earlier in this chapter.

VEW      DOX       XAJ

What are advantages of the forced-choice method?

In a forced choice test, you must guess even if you are not sure. This solves the problem of response bias, because everybody just say Yes to one and only one item. This also makes forced-choice testing a very sensitive measure of recognition memory, because people are forced to make a guess even if they are not sure about the answer, and usually they will guess at a better-than-chance level.

Write to Dr. Dewey at psywww@gmail.com.

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