Categorical perception occurs in newly learned faces, other-race faces, and inverted faces

Abstract

On the basis of findings that categorical perception (CP) is possible in complex visual stimuli such as faces, the present study tested for CP on continua between unfamiliar face pairs. Results indicate that CP can be observed for unfamiliar faces, in both familiar (same-race) and unfamiliar (other-race) groups. In addition, significant CP effects were observed in inverted faces. Finally, half-continua were tested where midpoint stimuli became endpoints. This was done to ensure that stimulus artifacts did not account for the observed CP effects. Consistent with the perceptual rescaling associated with Cp, half-continua showed a rescaled CP effect. We argue that these CP effects are based on the rapid acquisition of perceptual equivalence classes.Categorical perception (CP) occurs when discriminations between stimuli within one category are more difficult than discriminations between stimuli that span the boundary between categories. The question is, under what conditions does this occur? Initial research suggested that CP would be observed only for naturally occurring continua and was perhaps a sign of innate or highly practiced predispositions to break these continua into equivalence classes (e.g., Liberman, Harris, Kinney, & Lane, 1961). For example, Etcoff and Magee (1992) observed CP on continua between different facial expressions and suggested this supports the hypothesis that the perception of facial expression is innate. However, other findings suggest that such predispositions are not necessary to observe CP. In another study using faces, Beale and Keil (1995) found that participants perceive continua between individual familiar faces categorically. This is the case despite the likelihood that the continua between these faces have never been experienced by participants.IfCP is possible along artificial continua, then hypotheses assuming that CP is a sign of innate or even highly familiar perceptual categories are incorrect. Here, we explore two basic questions about the degree to which CP can be observed in the absence ofprevious learning. First, will it be possible to observe CP on novel continua between endpoints that do not have long-standing represen-The authors thank Robert Goldstone and Bill Merriman for reading drafts of this report and Stevan Hamad and Andy Young for many helpful discussions. Correspondence should be addressed to D. T. Levin, Kent State University, Department of Psychology, Kent Hall, Kent, OH 44121-0001 (e-mail: dlevin@kent.edu). J. M. Beale can be reached at the Department of Psychology, Grand Valley State University, Allendale, MI 49401 (e-mail: bealej@river.it.gvsu.edu).-Accepted by previous editor, Myron L. Braunstein tations associated with them as do familiar faces? A number of recent findings suggest that this kind of representation is not a necessary precondition for CPO This brings up the possibility that CP might be observed on continua between newly learned faces. Second, ifCP occurs on novel continua between novel endpoints, then under what conditions will such effe...

Face Familiarity, Distinctiveness, and Categorical Perception

“…Four experiments with faces support the original interpretation of categorical perception (CP) as only present for familiar categories. Unlike in the results of Levin and Beale (2000), no evidence is found for face identity CP with unfamiliar faces. Novel face identities were shown to be capable of encoding for immediate sorting purposes but the representations utilized do not have the format of perceptual categories.…”

“…CP has been demonstrated for initially unfamiliar faces (Goldstone, Lippa, & Shiffrin, 2001;McKone, Martini, & Nakayama, 2001;Viviani, Binda, & Borsato, 2007) but training in McKone et al (2001) was extensive (between 1,000 -10,000 trials; 2 -14 hr /participant/face pair) and considerable (15 min of similarity ratings plus 54 trials for each of four faces in a category learning task in Goldstone et al, 2001; thousands of preliminary identification trials on the morphed continua in Viviani et al, 2007). However, there are reports that brief exposure to unfamiliar faces can result in CP (Campanella, Hanoteau, Seron, Joassin, & Bruyer, 2003;Levin & Beale, 2000).…”

Altering object representations through category learning

“…Keil (1995, 1996) found that participants show categorical perception for continua between familiar faces. Levin and Beale (2000) found heightened discriminability at category boundaries even for unfamiliar and inverted faces, and conclude that such effects are based on the rapid learning of perceptual categories. Particularly strong categorical perception effects have been found when researchers have used similarity ratings rather than psychophysical measures of discriminability.…”

“…Whereas some researchers have found the primary impact of category learning to be decreasing people's confusions when making discriminations involving perceptual dimensions relevant to the categorization (Goldstone, 1994a;Levin & Beale, 2000), other researchers have found category learning to primarily increase similarity ratings between objects belonging to the same category (Kurtz, 1996;Livingston et al, 1998). One possible reason for this may be that psychophysical measures of discriminability seem to promote expansion whereas similarity ratings promote compression (Levin & Beale, 2000). Another proposed resolution is that if the categorized objects are extremely similar, then expansion is found; otherwise, compression is found (Livingston et al, 1998).…”

Concepts and Categorization

“…Other research has shown that prolonged experience with a domain such as dogs (Tanaka & Taylor, 1991) or faces (Levin & Beale, 2000;O'Toole, Peterson, & Deffenbacher, 1995) leads to development of a perceptual system that is tuned to these domains. Goldstone et al (2000) review other evidence for conceptual influences on visual perception.…”