Test Stimuli

Figure 5.3 Familiarization and test stimuli used to test adherence to the form similarity Gestalt organizational principle in Quinn, Bhatt, Brush, Grimes, and Sharpnack (2002). The rationale is that if infants can organize the familiar stimulus in the top panel into columns, then the vertical-column test stimulus should be perceived as familiar, and the horizontal-row test stimulus should be preferred. Similarly, if infants can organize the familiar stimulus in the bottom panel into rows, then the horizontal-row test stimulus should be perceived as familiar, and the vertical-column test stimulus should be preferred.

STIMULUS POSSIBLE ORGANIZATIONS

Figure 5.4 Intersecting circle-square stimulus in (a) and two possible organizations in (b) and (c). Adherence to the Gestalt principle of good continuation favors organization (b) over organization (c). (From Quinn, Brown, & Streppa, 1997.)

than the pacman shapes shown in panel (c). Presumably adults are following Gestalt organizational principles such as good continuation to represent the pattern information in this manner.

To determine whether 3- and 4-month-olds would parse and organize the pattern shown in Figure 5.4a into the square and circle shapes perceived by adults, a group of infants was familiarized in an experiment with the overlapping square-circle configuration and then preference tested with the circle versus P1 and the square versus P2. There are at least three ways in which infants may represent the familiar pattern information, each of which would produce a distinct pattern of looking among the test stimuli. First, if infants parse the pattern and organize its contours into the circle and square shapes in accord with the Gestalt principle of good continuation, then the circle and square shapes should be recognized as familiar in preference tests with P1 and P2, and P1 and P2 should be preferred. Second, if infants do not parse the unitary configuration, and the outcome is a representation of an unparsed whole, or if infants parse the configuration into more than one whole, but not the wholes predicted by adherence to good continuation, then one would not expect a consistent preference for P1 or P2 in either test. Third, infants may have spontaneous preferences for certain stimulus features (e.g., curvature, horizontal/vertical line elements) that could eventuate in parsing of the configuration and selective organization of the features into either the circle or square. In this case, one would expect a preference for the pacman shape (P1 or P2) in one or the other preference test, but not both. The results were that infants preferred the pacman shapes in both preference tests, a pattern of looking that is consistent with the idea that infants had organized the familiar configuration into the circle and square shapes in a manner predicted by adherence to the Gestalt principle of good continuation.

A potentially informative effect that was observed in Quinn et al. (1997) is that there was a spontaneous preference observed in a control group of infants who were assessed for possible a priori preferences among the test patterns. Specifically, without prior familiarization experience, the P2 shape was significantly preferred to the square. Although the novelty preference for P2 over the square in the experimental group occurred above and beyond that of the a priori preference for P2 in the control group, it is interesting to consider the possible significance of the spontaneous preference for P2.

The critical physical difference between P2 and the square is the presence of a curved contour in P2 and the absence of it in the square. In addition, there is evidence that infants have a spontaneous preference for curved over rectilinear contours (Fantz, Fagan, & Miranda, 1975). It is conceivable that the a priori preference for P2 is more than just a potential confound, a noise factor to be acknowledged, but then ruled out with appropriate statistical tests. The curvature-based preference for the P2 stimulus may help answer the question: How does the infant initially begin to break down a complex stimulus into a set of component contours? More specifically, where on the stimulus does the infant begin the complementary processes of parsing and organization? It may be that spontaneous preferences for some stimulus features over others could play an important "START HERE" role in initiating the parsing process for an unanalyzed configuration that contains a number of diverse features. A curvature preference, combined with a Gestalt principle like good continuation, may have allowed infants to first develop a representation for the circle shape. Once the circle was organized, infant attention may then have been free to explore other portions of the stimulus, thereby allowing for organization of the remaining contours into the square shape.

Summary

The evidence reviewed in the preceding sections indicates that young infants can group together the elements of a single visual pattern, presented in isolation from other patterns, so as to form a holistic representation of that pattern. Young infants may also be capable of parsing and organizing the more complex pattern information in a configuration of intersecting contours into two complete shapes. In achieving this degree of perceptual coherence infants may benefit from adherence to certain Gestalt principles such as lightness similarity and good continuation at 3 to 4 months, with form similarity beginning to exert a contribution to organization at 6 to 7 months. In addition, infants may rely on spontaneous preferences for particular features of contour information such as curvature to begin parsing and organizing global conglomerations of visual pattern information that contain multiple features.

The data contrasting the developmental onset of infants' use of lightness versus form similarity challenge the traditional Gestalt claim that all organizational principles are automatically and equivalently applied (Kohler, 1929). They are also consistent with recent studies from the adult literature suggesting that not all Gestalt principles are equally powerful or operational at the same time in the overall course of processing (Behrmann & Kimchi, 2003; Peterson, 2001). The findings suggest further that young infants are sensitive to more than just common movement and connected surface principles as organizers of visual pattern information (Kellman, 1996; Spelke, 1982). In particular, the findings of Quinn et al. (1993, 1997) indicate that lightness similarity and good continuation information are functional as organizational principles as early as 3 months of age (and possibly earlier in the case of lightness similarity; Farroni et al., 2000). These data are thus convergent with the work of Johnson (1997) and Needham (2001) in suggesting that a range of cues may be operational as sources for organization, although the difference in the developmental emergence of lightness similarity versus form similarity is consistent with the idea that some cues for organization may carry more weight than others at different points during development. As such, investigators may need to think in terms of how differentially weighted cues come together, in either a threshold or integration framework, to give rise to one or another percept.

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