Categorical results do not imply categorical perception.

Abstract

Categorical perception refers to the ability to discriminate between- but not within-category differences along a stimulus continuum. Although categorical perception was thought to be unique to speech, recent studies have yielded similar results with nonspeech continua. The results are usually interpreted in terms of categorical, as opposed to continuous, perception of both speech and nonspeech continua. In contrast, we argue that these continua are perceived continuously, although they are characterized by relatively large increases in discrim-inability near the category boundary. To support this argument, the amplitude rise time of a tone was varied to produce either an increase or a decrease in the intensity during the initial portion of the tone. A bipolar continuum of onset times increasing and decreasing in amplitude yielded traditional categorical results. However, when only half of this continuum was tested, subjects perceived the same sounds continuously. The finding of traditional categorical results along the bipolar continuum, when the sounds were shown to be perceived continuously in another context, argues against the use of traditional categorical results as evidence for categorical perception.