Perceptual and verbal mediation in the concept learning of children

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Some investigators have proposed that concept learning in humans can best be explained in terms of internalized processes mediating between the external stimulus and overt response. This approach contrasts with "single-unit" theory, emphasizing direct association between stimulus and response. Some psychologists advocate the developmental hypothesis that single-unit theory applies to lower organisms but that mediational theory holds for advanced organisms. Comparative psychological studies have yielded inconclusive findings with respect to this hypothesis. Some investigators have tried to experimentally influence the hypothesized mediating process by teaching subjects verbalizations which could serve as mediating responses. In general, findings suggest that older children utilize verbal mediators more readily than younger children. The current investigation stems from interest in whether young children have a specific inability to mediate verbally or a more general deficiency in mediation. Are mediating processes in young children possible on a “sensori-motor” level? The purpose of the present research is to compare younger and older children in their use of perceptual cues as a basis for mediation and in their preferences for perceptual versus verbal cues when these are in conflict. Fifty nursery-school children and seventy-five second-grade children learned two successive discriminations. The stimuli, cylinders varying in size (large-small) and brightness (black-white), were arranged on a tray before a vertical clown's face. The child put one of two stimuli taken from the tray into the clown's mouth and was rewarded, when correct, by the clown's nose blinking, an edible item, and praise. In the first discrimination a large, black cylinder was positive; in the second task the "small" object was rewarded, regardless of brightness. Since the first discrimination was solvable on the basis of either size or brightness (or both), the experimenter could attempt to influence the subject to make a mediating response to a particular dimension. The major experimental variables manipulated for this purpose during the initial discrimination were (1) kind of object arrangement on the tray, and (2) kind of verbal label children applied to the stimuli. The size arrangement, for example, had same-sized objects in proximity; but brightness was randomly distributed. In the size verbalization condition the child was instructed to precede his choices with the appropriate size label, i.e., "big" or "little." Independent groups received the following treatments at each age level: (1) size arrangement, (2) brightness arrangement, (3) size arrangement and brightness verbalization, simultaneously,(4) brightness arrangement and size verbalization, simultaneously, and (5) random arrangement, no verbalization (control). The major dependent variable was the mean number of trials to criterion on the second task, as it was assumed that ease of learning the "small" concept was an index of availability of the size dimension relative to the brightness dimension. The results indicated that both younger and older children responded in a mediational manner to the perceptual arrangements, suggesting that previous findings regarding lack of verbal mediation in young children should not be generalized to include other modes of mediation. The interfering effect of perceptually emphasizing an irrelevant dimension was stronger for younger children than for older children. Older children were more influenced than the younger children by relevant verbal cues. When relevant verbal cues were pitted against irrelevant perceptual cues, the former dominated with older children, but the latter with younger children. Younger children, however, were not influenced as predicted by relevant perceptual cues nor older children by irrelevant verbal cues . These discrepancies were discussed in terms of the nature of the experimental manipulations. It was tentatively concluded, subject to further verification, that younger children favor perceptual mediation and older children verbal mediation.



This thesis was digitized as part of a project begun in 2014 to increase the number of Duke psychology theses available online. The digitization project was spearheaded by Ciara Healy.



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