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Category production in response to script and category cues by kindergarten and second-grade children
JoURNAL OF APPLIED DEVELOPMENTAL PSYCHOLOGY 11,431-446
(1990)
Category Production in Response to Script and Category Cues by Kindergarten and Second-Grade Children KATHERINE NELSON AGATHA P. NELSON City University of New York Graduate Center
Two groups of kindergartners and one group of second gmden produced items from three familiar categories under one of two conditionr: with geneml taxonomic category instructions, and with instructions to produce items from twa script contexts for each category. Older children and kindergarten children with prior school experience produced more items than 5-year-olds without school experience. Second gmders produced more items in the toxonomic condition, ahho h kindergartners produced more in the script cue condition, indicating that the “B oder children had begun to integrate narrower script-based categories into broader taxonomic categories. Analyses of item arganixation indicated that all children relied upon eventcontext organization for the food and clothing categories, but no genemlly used organization emerged for the animal category.
Children’s understanding of taxonomic categories has been the topic of research in cognitive development for many years (e.g., Bruner, Olver, & Greenfield, 1966; Horton & Markman, 1980; Inhelder & piaget, 1964). It is clear that very young children can categorize objects on the basis of similarity at what has become known as the basic level (Nelson, 1973; Rosch, Mervis, Gray, Johnson, & Boyes-Braem, 1976; Sugarman, 1983), but their ability to classify at the superordinate level and to understand the superordinate-subordinate relation before the age of 7 or so has not been unambiguously established. Some research suggests that young children do have these capabilities (e.g., Smith, 1979; Waxman & Gelman, 1986) while other research (Horton & Markman, 1980; Inhelder & Piaget, 1964) suggests that they do not. Theoretical views of this achievement approach the issue from two different perspectives. On the one hand, Rosch (1975) assumes that categorization at different hierarchical levels rests on natural principles of abstraction from
Research reportedin this article was supportedin pan myNSF Grant BNS 82-08904. Correspondenceand requests for reprints should be sent to Katherine Nelson, Developmental Rychology, City University of New YorkGraduateCenter, 33 W. 42nd St., New York, NY 10036. 431
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correlated attributes in the real world, and that superordinate level categories differ from basic level only in the number and type of their common attributes. For example, the categoryfurniture is thought to be more difficult for children to acquire than the category chair because instances of furniture have fewer attributes in common, and the common attributes of chair include perceptual characteristics, particularly shape, which provide the basis for forming a prototypical image, whereas this is not true of furniture, for which the common attributes are functional rather than perceptual. Prom the perspective of Inhelder and Piaget (1964) the problem is a logical one, not one simply of abstracting common attributes and forming more general categories. In their well-known study of class inclusion, they showed that children younger than 7 years had difficulty coordinating the parts and wholes of subcategories (Rosch’s basic level) and superordinates. In their terms, younger children are incapable of coordinating intension and extension of classes. In contrast to both the natural abstraction view of Rosch and the logical view of Inhelder and Piaget, Nelson (1985) proposed that the evidence for superordinate categories in preschool children’s knowledge systems reflected a different type of organization than the logical class inclusion relation, and that this organization was not based on the abstraction of common attributes, but rather was derived from the child’s event schemas. In this view the emerging ability to understand the superordinate inclusion relation is a developmental product of the interaction of the child’s own first conceptual structures (which are not organized taxonomically) and the semantic structures of the language as displayed in adult uses. In brief, the proposal is that the child’s initial conceptual organization is in terms of general event schemas, for example, the event of lunch or getting dressed. These canonical schemas (or scripts) are organized in terms of a sequence of goal-oriented actions, and include, in many cases, sets of objects that can fulfill the “object-of-action” slot in an event. These objects represent alternative possibilities for different instantiations of an event: That is, they may or may not appear on different occasions of the same event. For example, a child might put on a dress on one occasion and a blouse and skirt or shirt and pants on another. These different clothes are considered “slot fillers” in the “putting clothes on in the morning” event. They may then come to constitute a “slot-filler category” for the child. Note that slot-filler categories may take the same label as general superordinate categories. For example, parents may say “Let’s put on your clothes” or “eat yourfood” (Lucariello & Nelson, 1986). Thus, the child may be alerted to the more general category structure through the use of the superordinate in different contexts. There is considerable evidence now that such categories have psychological reality for young children in a way that general taxonomic categories do not. Earlier research (Saltz, Soller, & Sigel, 1972) found that younger children’s categories were composed more narrowly than older children’s, consistent with the suggestion that preschool children rely upon context-restricted categories.
SCRIPT AND CATEGORY CUES
433
More recently, Lucariello and Nelson (1985) presented preschool children with a list of nine words drawn either from three general taxonomic categories (food, clothes, animals) or from three slot-filler categories (clothes to put on in the morning, lunch foods, zoo animals). They found that children clustered the slotfiller items more in recall, and recalled significantly more from the slot filler than from the taxonomic list. This finding has since been replicated and extended by Rosner and Smick (1989) and Krackow and Blewitt (1989). Additional evidence for slot-filler organization of superordinate category knowledge comes from studies of word associations, a category production task, and a forced-choice picture task with 4- and 7-year-old children (Kyratzis, Lucariello, Nelson & Greenstein, 1987; Nelson, 1988). These studies showed that slot-filler organization continued to play a strong role in the composition of children’s category knowledge at 7 years. Thus, it does not appear to be a phenomenon that disappears as more mature category knowledge is attained. The proposal is that young children attain understanding of taxonomic category structure by coordinating their initial slot-filler categories with the broader inclusion structures that are represented in natural language. This proposal has important implications for educators and others working with children in the preschool and early school years. The fact that children use the same terms (e.g., food) as adults, does not mean that they have the same understanding of what is implied by the term. This is a point that Vygotsky (1987; Wertsch 1984) emphasized, but in Vygotsky’s view, children’s early conceptual structures were deflcient, reflecting complexive organization rather than categorical. The present view is that children’s structures are categorical, but rest on a narrower, contextrestricted base. Children may need specific verbal instruction to enable them to move beyond their initial spontaneous formations of category knowledge. The proposal that children derive their initial categories from schemas representing their experientially based knowledge implies that children with different experience in the real world will form different category structures (Nelson, 1986). Again, this has implications for educators. This study examined the category structures of children from an inner-city neighborhood in an effort to explore the nature of experiential differences that might be expected. This research was designed to extend the previous findings regarding the relation of slot-filler categories to more general taxonomic categories in several ways. First the study employed a category production paradigm that explicitly draws on the child’s ability to produce category members in response to superordinate terms, and that has been successful in previous work in delineating children’s category knowledge (e.g., Anglin 1977; Kyratzis et al., 1987; Nelson 1974, 1978). The goal here was to differentiate items produced in this task on the basis of their membership in different slot-filler categories, and to determine the extent to which 5- and 8-year-old children rely on such categories in their productions. In a similar task Kyratzis et al. (1987) showed that 4- and 7-year-olds cluster slot-filler items within the categories used here. Second, different instructions were used for children in different groups in
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order to determine whether slot-filler category cues would elicit category items more successfully for these children than would general category cues. Third, the sample used in this study differed from those in other studies in ways that allowed us to evaluate the effects of early school experience on the construction of category knowledge independent of age. All children were from a relatively low socioeconomic group in a large city. One group of 5-year-olds had had prior schooling experience, whereas members of the other kindergarten group were new to school. Thus, in addition to comparing 5-year-olds with 8year-olds, we could compare the two groups of 5-year-olds in terms of their prior school experience. In summary, the questions to be addressed in this study are the following: Do slot-filler category instructions aid younger children in producing category members? Do children organize category items in terms of slot fillers to a greater extent than in terms of conventional subcategories? Does exposure to category usage in school settings improve children’s ability to utilize category information? METHOD Subjects Three groups of children from a public school in a lower to lower-middle-class urban neighborhood participated in the study. One group of kindergarten children (Kl) consisting of 8 boys and 8 girls (M = 5 years, 4.6 months) had had no prior preschool experience. A second group of kindergarten children (K2) consisting of 7 boys and 7 girls (M = 5 years, 6 months) had previously attended day-care centers, nursery school, or Head Start programs. One group of second graders (M = 8 years, 1.7 months) included 8 boys and 8 girls. Procedure Children were interviewed individually in a quiet room at the school. They were randomly assigned to one of two conditions for the category production task. In the taxonomic condition children were asked to produce as many items as they could in three general categories: animals, clothing, and food. In the slot-filler condition, children were asked to name as many items as they could from categories within particular contexts, namely animals found at the zoo or on a farm; clothes worn inside or outside; foods eaten for breakfast or lunch. The instructions for the taxonomic condition were as follows: We are going to play a game. I am going to say the names of some things. After I say a name, you tell me all the things you can think of that belong with that name. For instance, I may say ‘tools’ and you might think of hammer, pliers, screwdriver, and lots of other things. Or I might say ‘toys.’ Can you tell me what you would think of if I say ‘toys?’ (child responds) Those are very good. You could probably
SCRIPT AND CATEGORY CUES
435
have thought of (interviewer names other toys) or lots of other things too. Okay, now remember, each time I tell you a word, you say all the things you can think of that belong with the word I say. Try to name as many things as you can. Children in the slot-filler condition were given the same instructions except that the examples the interviewer used were “furniture you find in the living room” with couch, chair, and table as instances; and “toys you play with outside.” All children were encouraged, when necessary, to produce more items 7” with such prompts as “Can you think of any other RESULTS Group x Condition Analysis Responses that were inappropriate to a category or that repeated items already given were eliminated from the analysis. Then mean number of responses by each child in each category was tabulated and entered into a three-way repeated measures ANOVA (3 X 2 X 3) with group and condition as between-subject variables and category as the repeated measure. This analysis revealed a main effect of group, F(2,40) = 8.17, p < .OOl, a main effect of category, F(2,80) = 10.23, p < .002, a Group X Condition interaction, F(2, 40) = 4.82, p < .Ol, and a Group x Condition X Category interaction, F(4, 80) = 3.74, p < .007. Planned comparisons were used to test hypothesized differences. Cell means are displayed in Table 1, where the nature of the interactions is revealed. The main effect of group rests on the fact that, overall, the second graders produced more than the kindergartners, F( 1,40) = 12.23, p < .002, and the K2s produced more than the Kls, F(l, 40) = 3.58, p < .06. The main effect
Mean Number
TABLE 1 of Kerns Produced by Group, Condition
and Category
~wlory Group/Condition
N
Animals
Clothina
Food
M
Kl Taxonomic Slot-filler
8 8
5.88 6.25
4.00 9.12
7.88 10.87
5.92 8.75
K2 Taxonomic Slot-filler
7 7
8.86 11.29
7.57 12.43
9.43 19.00
8.62 14.24
Grade 2 Taxonomic Slot-filler
8 8
17.25 14.00
13.00 10.62
27.63 12.25
19.29 12.29
10.66 10.51
8.19 10.73
14.98 14.04
11.28 11.76
Mean Taxonomic Mean Slot-filler
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of category is found in the fact that, overall, more items were produced in the food category than in either of the others. (This is examined within grades and conditions later.) The interesting Group X Condition interaction reveals that, whereas the kindergarten groups produced more items in the slot-filler condition than in the taxonomic condition, the opposite was true for the second graders. (The condition contrast was not significant for Kl; for K2 it approached significance, F( 1, 40) = 3.16, p < .08; for Grade 2, F(1,40) = 5.60, p < .02. As shown in Table 1, this result was consistent for each category separately at each age, although only three of the individual condition post hoc comparisons within category were significant at the .05 level (clothing for the Kl group, p < .005; food for the K2 group, p < .Ol; and food for the Grade 2 group, p < 305). The Group X Condition X Category interaction can be seen in the consistent order of categories for both kindergarten groups in the slot-filler condition in number of items produced: Animals < Clothing < Food. The order of animals and clothing in the taxonomic condition is reversed, but this reversal is not significant. For the 7-year-olds, however, the order in the two conditions is quite different. It is especially noteworthy that in the slot-filler condition, secondgrade children actually produced fewer food items than did the children in K2 (although not significantly), whereas in the taxonomic condition they produced significantly more (almost 3 times as many), F( 1, 40) = 11.09, p < .002. Thus, the quantitative analysis of item responses provides initial answers to two of the questions posed. Taxonomic and slot-filler instructions had differential effects on item production, but those effects differed for the two ages. Younger children tended to produce more items when they were asked to produce items within each of two slot-filler categories than when they were asked to produce from the general taxonomic category. In contrast, older children produced significantly more items when they were given general taxonomic instructions than when their responses were directed to the narrow slot-filler categories. This finding suggests that their categories had become more general and complex, integrating items from a number of different slot-filler or other subcategories. Second, the two groups of kindergartners differed in their ability to produce category items in both conditions. Children in K2 who had had preschool experience produced more items than those without such experience. On the assumption that preschools emphasize categorical organization in their instructional programs, this finding supports the proposal that the acquisition of categorical knowledge is a function not only of individual cognitive development but of social-linguistic sharing of knowledge. The remaining analyses focused on the production and organization of items within categories. Category
Analyses
One indication of category knowledge is the number of inappropriate items produced. Table 2 shows the proportion of inappropriate items in each category
SCRIPT AND CATEGORY CUES
Proportion
TABLE 2 of Inappropriate
Animals Farm ZOO
.153
Clothing Inside Outside
.lll
Food Breakfast Lunch
M
Responses
K2
Kl Taxonomic
Slot-filler
Taxonomic
Grade 2 Slot-filler
Taxonomic
0 .170
.093
0
0
.I11
0
.060
.096
0
0 0
0
0
Slot-filler
.045
.645 .142
0
0
.119 .044 .I26
437
0 0 .040
.025 0 .017
in each condition for each age group. As is evident in this table, the largest number of inappropriate items was produced by the Kl group (overall M = 0.128). Even for this group, however, there were relatively few inappropriate items in any category except the farm animal category where 64.5% of their responses were judged inappropriate. The primary inappropriate items produced by the other groups were also in this category. It is not surprising that these lower income children from an inner-city environment might have difficulty with these items. Indeed, it seems plausible that this category did not in any way constitute a slot-filler category for them, there being little opportunity for them to derive it from real life experience or from books or television. In contrast, most of these children did have direct experience with zoo animals, because there was a nearby zoo that was regularly visited by school groups and presumably by many family groups as well. Again, the effects of prior preschool experience can be seen here in that neither the K2 nor the Grade 2 children produced many inappropriate items. Mean numbers of responses within each subcategory for the children in the slot-filler category condition are shown in Table 3. As seen in inappropriate responses, the children’s limited knowledge of farm animals is also evident here. There were no group differences in this subcategory. For zoo animals, both Grade 2 and K2 children produced significantly more responses than Kl children. The difference between farm and zoo animals was significant for the Grade 2 children, p = .003, but not for either of the other groups. For the clothing category, the primary findings of interest are that K2 children produced significantly @ < .05) more inside clothes than the Kl children, but there were no other significant differences between groups or categories. For the food categories, the notable finding is that the K2 group produced significantly more than either the Kl or the Grade 2 group in both the breakfast and lunch categories. The explanation for these differences is no doubt different
NELSON AND NELSON TABLE 3 Mean Numbw of items Produced in Slot-Hller Catagories Kl
K2
Grade 2
4.43 5.38
6.00 7.86
6.13 9.38
Clothing inside Outside
5.00 6.75
7.29 7.86
5.13 8.50
K2 > K1.p < .04 n.s.
Food Breakfast
5.71
9.00
6.13
Lunch
6.50
11.00
8.50
K2 > Kl, p < .Ol K2 > 2, p < .05 K2 > Kl, K2 > 2, p < .004
Animals Farm ZOO
Group Difference
. .
2sKl:;<.OO4 K2 > Kl, p < .05
in the two cases, however, as indicated by the different direction of results in the taxonomic condition. That is, it is clear that Grade 2 children know many more food items than they produced in this condition, whereas Kl children are not able to call upon more knowledge in the general category situation than in the restricted-meal context condition. Category Organization The organization of category members in terms of the order of their production can be considered, at least loosely, to reflect the underlying conceptual organization. Three different types of organization are considered here: typicality according to adult and child norms, hierarchical taxonomic subcategorization, and event-context organization. Typic&y. Typicality has emerged as an important basis for category organization since Rosch’s (1975) work. Categories are thought to be organized around the most typical members; thus, in category production tasks, more typical members arc generally produced first. More typical members are also expected to be learned before atypical ones. It might be questioned as to whether the children in this study, who represent a different population than that usually studied in developmental psychology (or cognitive psychology in general) display the same tendencies to produce typical items more frequently, or whether the items they do produce reveal different bases of typicality. Bjorklund, Thompson, and Ornstein (1983) gathered typicality ratings from middle-class kindergarten, third-grade and sixth-grade children, and adults in 12 natural language categories. Only one of these, clothing, overlapped with the categories in this study. Bjorklund et al. used subcategories of both food (fruits,
SCRIPT AND CATEGORY CUES
439
vegetables) and animals (dogs, birds). Nelson (1974) also used subcategories of food (fruits, vegetables). When the productions of the children in this study were compared in terms of frequency with the typicality ratings of the children in Bjorklund et al’s study for children in comparable age groups, there was considerable consistency, despite the difference in samples and tasks. The most typical items for the Syear-olds in the Bjorklund et al. study were (from most to least typical): pants, dress, shirt, coat, shoes, socks. The most frequent for the kindergartners in Condition 1 in the present study were (in order): pants, shirts, undershirt, sweater, socks, shoes, and dress. Five of the seven most frequently mentioned items were those rated most typical in the Bjorklund et al. study. The other two items (sweater and undershirt) were not included in their ratings. The kindergarten order is even more consistent with that produced by Syear-olds in the Nelson (1974) study. Those data were actually gathered in 1968 from uppermiddle-class children in California. The order in that study was: pants, shirt, dress, shoes, socks, shorts, and sweater. Similar results were found comparing Bjorklund et al’s typicality ratings by 8-year-olds with the present frequency data from second-grade children. The typicality ratings were: shirt, pants, dress, coat, shoes, and socks, from most to least typical. The frequency order in the present study was: shirt, (pants, shoes}, {dress, socks}, {sweater, skirt}, {blouse, undershirt}. Again, the order in the present study is even more consistent with Nelson’s (1974) order: pants, {shirt, socks}, shoes, dress, skirt, fiacket, underwear, hat}, and sweater. The only notable discrepancy in these lists is that the children in this study mention undershirt frequently (an item not ranked by the Bjorklund subjects), and the typicality ratings rank coat very typical, although that item is not mentioned either by the present subjects or the children in the Nelson (1974) study. Older children in the 1974 study did mention jacket and hat, however, among their most frequent items, and it should be noted that coats were infrequently needed or worn by children in the Los Angeles area. It might, therefore, be speculated that the absence of any outerwear among the most frequent items, even for the older children in this study, reflects their reliance upon relatively unintegrated context-determined organization. Comparison of the most frequently produced animal items in this study and in the Nelson (1974) study also showed similar orders. In particular, the younger children in this study produced zoo animals most frequently (elephant, giraffe, zebra, lion) as did the Nelson (1974) 5-year-olds (lion, giraffe, elephant, tiger). In contrast, the 8-year-olds in both studies included domestic animals (dog, cat) among the most frequent. Thus, the most frequently produced items in this study do seem to reflect the typicality structure of taxonomic categories to the same extent as other studies of young children have found, with some minor exceptions. However, these findings are based upon group data. To examine the other types of organization previously referred to, it is necessary to analyze the order of individual productions more carefully.
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NELSON AND NELSON
Organization by Conventional Subcategories and by Event-Context Categories In this section the output by each child for each category in the taxonomic condition is analyzed in terms of two contrasting methods of organization: conventional subcategories and event-context categories. For this purpose each item on each child’s list was coded in order of its output twice, once for the presumed event in which it was usually experienced, and once in terms of a conventional subcategorization system for foods, clothes, and animals. Table 4 lists the event contexts under each major category and the subcategories used for the conventional analysis. Some cautions should be noted with respect to the interpretation of these data. Assigning items to categories is not always straightforward; fuzzy boundaries and ambiguities exist for both types of organization. (However, very few ambiguous codings would have changed the numbers that enter into the following analyses.) In addition, the number of possible subcategories differs for the two types of organization and for different categories. Also, because the comparisons are between two types of analysis and not between conditions or groups, inferential statistics do not appear to be applicable. The analyses are nonetheless presented for their qualitative interest. TABLE 4 Subdivisions Used in Category Analysis Clothing
Animals
Food
Conventional Subcategories
mammals fish birds insects rodents0 marsupials amphibians reptiles worms mollusks
Context Subdivisions zoo animals farm animals pets/home woods/park animals found in water
meat
outerwear underwear sports footwear outdoorwear headwear nightwear accessories
vegetables fruit cereal pasta dairy beverages breads cakes condiments candy nuts soup manufactured foods
day/indoor clothes outdoor clothes sports clothes adult clothes nightclothes
aAlthough rodents are mammals, tinct group by lay people.
breakfast dinner lunch snack dessert
they tend to be treated as a dis-
441
SCRIPT AND CATEGORY CUES
Mean Number
TABLE 5 of Subdivisions and Category
Animals Conventional Kl K2 Grade 2
M
Clothes
Subcategories 1.57 2.29 3.75 2.54
Script Contexts Kl 2.57 K2 2.57 Grade 2 4.62 M 3.25
by Group
Food
3.29 3.43 4.12 3.61
3.88 3.86 8.62 4.78
1.71 2.29 2.75 2.25
2.29 2.57 4.0 2.95
The first analysis was in terms of how many subcategories a child included on the list and how many items came from each. Tables 5 and 6 display these figures. Table 5 shows the mean number of subcategories and the mean number of event contexts used at each grade for each main category. It can be seen that, in general, the number of subcategories increased in a more or less linear fashion with development for both types of subdivisions and for all three categories. The exceptions were the number of food categories, which did not differ between the two kindergarten groups, and the number of event categories, which also did not differ for these two groups. It appears that for both events and subcategories there are more subdivisions for food than for clothes; this outcome must be borne in mind in the following analysis. But note that for the animal category, there are fewer subcategories used than for food and clothing, whereas there are more event contexts used than for the others. This too will be important in subsequent analyses. The number of animal subcategories revealed here reflects the fact that although there are a large number of possible subdivisions, the vast majority of animals children named are in fact mammals, the large major subcategory of the animal class most familiar to them.
Number
TABLE 6 of ftems per Subdivision by Group and TVpe of Organization Conventionai
No. of Cat. Kl K2 Grade 2
M
2.90 3.19 4.83 3.64
Context
Items/Cat. 2.04 2.70 3.99 2.91
No. of Cat.
Items/Cat.
2.19 2.48 3.79 2.82
2.70 3.48 5.09 3.76
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NELSON AND NELSON
Table 6 compares the number of categories with the number of items per category for each grade in each type of organization. Here it can be seen that if the lists are assumed to be organized in terms of conventional subcategories, they will contain a fairly large number of categories (ikf = 3.64) in comparison to the number of items in each category (M = 2.91). On the other hand, if the list is considered to be organized in terms of events, there will be relatively fewer contexts recalled (M = 2.82) compared to the number of items in each context (M = 3.76). The subcategory assumption suggests a rather shallow organization, the event-context assumption indicates a deeper organization (more items per node). Although these data cannot decide definitively between these two possibilities, further analysis sheds additional light on the matter. In this analysis the average length of run was computed for each list by context and by subcategory. The subdivisions were those shown in Table 4. A run consists of the consecutive occurrence of items from the same subdivision. In practice, the number of runs in a list is computed by counting the number of shifts from one subdivision to another (including the initial shift to begin naming). For example, in the list tiger, elephant, dog, cat, squirrel, there are two runs (4 mammals followed by 1 rodent) with a mean length of 2.5 in the conventional analysis, and three runs (2 zoo animals, 2 home animals, and 1 woods or park animal) with a mean length of 1.67 in the context analysis. Table 7 displays these results. Here it is apparent that length of run differs for the two types or organization. Runs by context overall average 3.15 compared to 2.5 1 for conventional categories, suggesting that the context organization has greater psychological reality or greater coherence. However, there are some peculiarities to be noted. First, the expected age difference is reversed, with the more advanced kindergarten group producing longer runs than the second graders. This is explicable in terms of the larger number of subdivisions second graders produce (see Tables 5 and 6) and in their larger number of items. Number of runs is a function of length of list and number of subcategories in addition to clustering of items within subcategories. Note again the difference between animals and the food and clothing categories. In the latter categories, runs are substantially longer for the context analysis TABLE 7 Mean Length of Runa by Type of Organization Conventional
Kl K2 Grade 2 M
Context
Animals
Clothina
Food
Animals
Clothina
Food
2.57 5.19 3.02 3.59
1.27 2.48 2.04 1.98
1.93 2.49 1.54 1.99
1.71 2.79 2.89 2.40
2.04 4.57 3.07 3.23
3.18 4.52 3.79 3.83
SCRIPT AND CATEGORY CUES
443
than for the conventional, again suggesting that the context type of organization has greater psychological reality for the children. But for animals, the situation is reversed, with substantially longer runs for conventional subdivisions. Again, this is the result of children’s naming members of the mammal subcategory. Even though they know and can name other types (e.g., snake, fish, bird, rabbit, kangaroo), the majority of the most familiar animals, whether from farm, zoo, house, or park, belong to the mammal category. In this case, therefore, the context organization subdivides the category more finely than does the taxonomic organization (despite the greater potential for more subcategories for the taxonomic organization). The food category overall produced the longest runs. Children typically clustered together items from the same meal, often slot fillers such as meats, vegetables, pasta, or desserts. The fact that these were meal clusters rather than subcategory clusters is apparent in the fact that the context runs over all groups were almost twice as long as the conventional runs. GENERAL DISCUSSION This study has provided additional support for the proposal that young children’s superordinate categories are organized in terms of their event knowledge, in particular, in terms of slot-filler categories. It was shown first of all, that kindergarten children produced no more items on a category production task when they were allowed to produce category members freely from any context, than when they were given specific event-context cues. Indeed, they produced more in the latter condition (approaching significance), suggesting that their categories were organized according to specific events. Second graders, however, were found to produce significantly more items in the general category condition, suggesting that they had integrated the different event contexts into a larger structure. Children at both ages tended to produce items found to be most typical in other studies with children most frequently. Thus, the inner-city children in this study did not deviate from the category content-structure of the animals and clothes categories found with middle-class children. However, the food category used here could not be compared with the other groups, and this domain might well have revealed differences among groups based on different experiences. In addition, it was found that children in this study did not have a well-established farm animals category, reflecting their relatively restricted urban experience. Their experience with visits to the zoo, however, presumably provided the basis upon which they readily produced instances of typical zoo animals. A further restriction on their categories was seen in the low frequency of mention of outdoor clothing such as coats, in comparison to other studies. We do not believe that they did not have experience with coats, but rather that their categories were organized in a context-restricted way such that outdoor clothing was not entered into the general clothing category.
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When conventional subcategories were contrasted with context-based event categories in the analysis of the children’s output, it was found that for the clothes and food categories, context-based subdivisions produced more items per category and longer runs, whereas conventional categories produced more subcategories with fewer items per category and shorter runs. Thus, children’s clothes and food categories appeared to be best characterized in terms of eventbased organization. The animal category, however, produced both a larger number of subcategories and longer runs in the conventional analysis. It was noted that this was the result of the overwhelmingly dominant number of mammals in the lists. In the case of this category, the context-based organization divides the group more finely, but we cannot claim that either type of organization of animals has greater psychological validity because of the large and diverse membership in the mammal subclass. Theories of category knowledge acquisition outlined in the introduction do not address the issues of variation among children in categorical content and structure, or the basis for development of hierarchically organized categories. As we have seen, children’s first superordinate categories are not based so much upon common attributes, as Rosch’s (1975) work would suggest, but on common context. And in this study, as well as in Kyratzis et al. (1987), organization by context appears to be as much a characteristic of 7- and &year-olds’ categories as it is of 4- and Syear-olds.’ The fact that 8-year-olds in this study had more general and presumably better integrated categories than did the Syear-olds might suggest that they had advanced to a better understanding of class inclusion in the terms of Inhelder and Piaget (1964). However, there is no independent evidence of this, and an alternative possibility is that they have extended their understanding of the semantics of the superordinate terms to include what were initially context-restricted subdomains of knowledge. To the extent that this is the case, it suggests that education can play an important role in advancing children’s category knowledge. In contrast, both the natural abstraction view (represented in Rosch’s work) and the logical construction view (I&elder & Piaget) imply that category development proceeds according to an internal developmental timetable that is not amenable to external influence. A further finding in this study supports this suggestion. The low-income kindergarten children who had had preschool experience were able to produce more category items, and appeared to have those items organized better than those who had not had these experiences. This suggests that category knowledge is a joint function of the child’s own organization and exposure to the organization used by others, particularly in school settings. We can summarize these points in the following way: l
All children can be expected to categorize objects in their environments based on their own experience.
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Knowledge of the role of objects in familiar events provides a sound basis for such categorization. When experiences are widely shared across a culture, these categories will have similar content and structure, as found here for the clothes and animals categories. Nonetheless, there may be specific restrictions on content, as also found, and some spontaneously formed categories may vary across groups with varying experiences. Spontaneous categories become consolidated, integrated, and broadened in . contact with others, especially adults, who provide examples of the use of superordinate terms across specific contexts. Thus, children who initially do not include snacks in the food category, or who fail to include coats in the clothing category, may learn to extend their category knowledge when adults make such inclusion explicit. In this way, children may be led to construct hierarchical category structures that reproduce the taxonomies of the natural language system. Schools cannot expect the child to arrive at these on their own, or that they will come to school with a common organization of category knowledge even in familiar domains. However, even very young children with limited experience do have the basis for building general categories from their experientially derived knowledge representations. Recognizing both the context-specific basis of their categorical structures and the possibility of their integration into larger taxonomic domains is important to the task of bringing all children into a common universe of discourse about even the most mundane categorical knowledge systems. REFERENCES Anglin,J.M.
(1977). Word, object, and concephud developmenr. New York: Norton. Bjorklund, D.F., Thompson, B.E., & Ornstein, P.A. (1983). Developmental trends in children’s typicality judgments. Behavioral Research Methods and Instrumentarion, IS, 350-356. Bruner, J.S., Olver, R.R., & Greenfield, P.M. (1966). Studies in cognitive growth. New York: Wiley. Horton, M.S., & Markman, E.M. (1980). Developmental differences in the acquisition of basic and superordinate categories. Child Developmen& 51, 708-719. Inhelder, B., & Piaget, J. (1964). The early growth oflogic in the child. New York: Harper & Row. Krackow, E., & Blew&, P. (1989, March). What derermines order of acquisition of taxonomic relationships? Paper presented at the annual meeting of the Southeastern Psychological Association, Washington, DC. Kyratzis, A., Lucariello, J., Nelson, K., & Greenstein, C. (1987, April). The schematic to raxorwmic shifr revisited: Category construction in preschool nnd school-aged children. Poster presented at the biennial meeting of the Society for Research in Child Development, Baltimore, MD. Lucariello, J., & Nelson, K. (1985). Slot-filler categories as memory organizers for young children. Developmenral Psychology, 21, 272-282.
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Lucariello, J., & Nelson, K. (1986). Context effects on lexical specificity in maternal and child discourse. Journal of Child Language, 13, 501-522. Nelson, K. (1973). Some evidence for the cognitive primacy of categorization and its timctional basis. Merrill-Palmer Quarterly Journal of Behavior and Development, 19, 21-39. Nelson, K. (1974). Variations in children’s concepts by age and category. CM-l Development, 45, 577-584.
Nelson, K. (1978). Semantic development and the development of semantic memory. In K.E. Nelson (Ed.), Children’s language. New York: Gardner Press. Nelson, K. (1985). Making sense: The acquisition of shared meaning. New York: Academic. Nelson, K. (1986). Evenr knowledge: Structure andfunction in development. Hillsdale, NJ: Brlbaum. Nelson, K. (1988). Where do taxonomic categories come from? Human Development, 31, 3-10. Rosch, E. (1975). Cognitive representations of semantic categories. Journal of Experimental Psychology: General, 104, 192-233. Rosch, E., Mervis, C.B., Gray, W.D., Johnson, D.M., & Boyes-Braem, P. (1976). Basic objects in natural categories. Cognitive Psychology, 8, 382-439. Rosner, S.R., & Smick, C. (1989, April). Cueing maintenance of slot-filler and taxonomic categories. Poster presented at the biennial meeting of the Society for Research in Child Development, Kansas City, MO. Saltx, E., Soller, E., & Sigel, I.E. (1972). The development of natural language concepts. Child Development, 43, 1191-1202. Smith, CL. (1979). Children’s understanding of natural language hierarchies. Journal of Experimental Child Psychology,
27, 437-458.
Sugarman, S. (1983). Children’s early thought: Developments in classification. New York: Cambridge University Press. Vygotsky, L.S. (1987). Thinking and speech. In R.W. Rieber & A.S. Carton (Bds.), The collected works of L.S. Vygotsky (Vol. 1). New York: Plenum. Waxman, S.R., & Gelman, R. (1986). Preschoolers’ use of superordinate relations in classification and language. Cognitive Development, I, 139- 156. Wertsch, J.V. (Ed.). (1984). Culture, communication, York: Cambridge University Press.
and cognition: Vygotskian perspectives.
New
(1990)
Category Production in Response to Script and Category Cues by Kindergarten and Second-Grade Children KATHERINE NELSON AGATHA P. NELSON City University of New York Graduate Center
Two groups of kindergartners and one group of second gmden produced items from three familiar categories under one of two conditionr: with geneml taxonomic category instructions, and with instructions to produce items from twa script contexts for each category. Older children and kindergarten children with prior school experience produced more items than 5-year-olds without school experience. Second gmders produced more items in the toxonomic condition, ahho h kindergartners produced more in the script cue condition, indicating that the “B oder children had begun to integrate narrower script-based categories into broader taxonomic categories. Analyses of item arganixation indicated that all children relied upon eventcontext organization for the food and clothing categories, but no genemlly used organization emerged for the animal category.
Children’s understanding of taxonomic categories has been the topic of research in cognitive development for many years (e.g., Bruner, Olver, & Greenfield, 1966; Horton & Markman, 1980; Inhelder & piaget, 1964). It is clear that very young children can categorize objects on the basis of similarity at what has become known as the basic level (Nelson, 1973; Rosch, Mervis, Gray, Johnson, & Boyes-Braem, 1976; Sugarman, 1983), but their ability to classify at the superordinate level and to understand the superordinate-subordinate relation before the age of 7 or so has not been unambiguously established. Some research suggests that young children do have these capabilities (e.g., Smith, 1979; Waxman & Gelman, 1986) while other research (Horton & Markman, 1980; Inhelder & Piaget, 1964) suggests that they do not. Theoretical views of this achievement approach the issue from two different perspectives. On the one hand, Rosch (1975) assumes that categorization at different hierarchical levels rests on natural principles of abstraction from
Research reportedin this article was supportedin pan myNSF Grant BNS 82-08904. Correspondenceand requests for reprints should be sent to Katherine Nelson, Developmental Rychology, City University of New YorkGraduateCenter, 33 W. 42nd St., New York, NY 10036. 431
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correlated attributes in the real world, and that superordinate level categories differ from basic level only in the number and type of their common attributes. For example, the categoryfurniture is thought to be more difficult for children to acquire than the category chair because instances of furniture have fewer attributes in common, and the common attributes of chair include perceptual characteristics, particularly shape, which provide the basis for forming a prototypical image, whereas this is not true of furniture, for which the common attributes are functional rather than perceptual. Prom the perspective of Inhelder and Piaget (1964) the problem is a logical one, not one simply of abstracting common attributes and forming more general categories. In their well-known study of class inclusion, they showed that children younger than 7 years had difficulty coordinating the parts and wholes of subcategories (Rosch’s basic level) and superordinates. In their terms, younger children are incapable of coordinating intension and extension of classes. In contrast to both the natural abstraction view of Rosch and the logical view of Inhelder and Piaget, Nelson (1985) proposed that the evidence for superordinate categories in preschool children’s knowledge systems reflected a different type of organization than the logical class inclusion relation, and that this organization was not based on the abstraction of common attributes, but rather was derived from the child’s event schemas. In this view the emerging ability to understand the superordinate inclusion relation is a developmental product of the interaction of the child’s own first conceptual structures (which are not organized taxonomically) and the semantic structures of the language as displayed in adult uses. In brief, the proposal is that the child’s initial conceptual organization is in terms of general event schemas, for example, the event of lunch or getting dressed. These canonical schemas (or scripts) are organized in terms of a sequence of goal-oriented actions, and include, in many cases, sets of objects that can fulfill the “object-of-action” slot in an event. These objects represent alternative possibilities for different instantiations of an event: That is, they may or may not appear on different occasions of the same event. For example, a child might put on a dress on one occasion and a blouse and skirt or shirt and pants on another. These different clothes are considered “slot fillers” in the “putting clothes on in the morning” event. They may then come to constitute a “slot-filler category” for the child. Note that slot-filler categories may take the same label as general superordinate categories. For example, parents may say “Let’s put on your clothes” or “eat yourfood” (Lucariello & Nelson, 1986). Thus, the child may be alerted to the more general category structure through the use of the superordinate in different contexts. There is considerable evidence now that such categories have psychological reality for young children in a way that general taxonomic categories do not. Earlier research (Saltz, Soller, & Sigel, 1972) found that younger children’s categories were composed more narrowly than older children’s, consistent with the suggestion that preschool children rely upon context-restricted categories.
SCRIPT AND CATEGORY CUES
433
More recently, Lucariello and Nelson (1985) presented preschool children with a list of nine words drawn either from three general taxonomic categories (food, clothes, animals) or from three slot-filler categories (clothes to put on in the morning, lunch foods, zoo animals). They found that children clustered the slotfiller items more in recall, and recalled significantly more from the slot filler than from the taxonomic list. This finding has since been replicated and extended by Rosner and Smick (1989) and Krackow and Blewitt (1989). Additional evidence for slot-filler organization of superordinate category knowledge comes from studies of word associations, a category production task, and a forced-choice picture task with 4- and 7-year-old children (Kyratzis, Lucariello, Nelson & Greenstein, 1987; Nelson, 1988). These studies showed that slot-filler organization continued to play a strong role in the composition of children’s category knowledge at 7 years. Thus, it does not appear to be a phenomenon that disappears as more mature category knowledge is attained. The proposal is that young children attain understanding of taxonomic category structure by coordinating their initial slot-filler categories with the broader inclusion structures that are represented in natural language. This proposal has important implications for educators and others working with children in the preschool and early school years. The fact that children use the same terms (e.g., food) as adults, does not mean that they have the same understanding of what is implied by the term. This is a point that Vygotsky (1987; Wertsch 1984) emphasized, but in Vygotsky’s view, children’s early conceptual structures were deflcient, reflecting complexive organization rather than categorical. The present view is that children’s structures are categorical, but rest on a narrower, contextrestricted base. Children may need specific verbal instruction to enable them to move beyond their initial spontaneous formations of category knowledge. The proposal that children derive their initial categories from schemas representing their experientially based knowledge implies that children with different experience in the real world will form different category structures (Nelson, 1986). Again, this has implications for educators. This study examined the category structures of children from an inner-city neighborhood in an effort to explore the nature of experiential differences that might be expected. This research was designed to extend the previous findings regarding the relation of slot-filler categories to more general taxonomic categories in several ways. First the study employed a category production paradigm that explicitly draws on the child’s ability to produce category members in response to superordinate terms, and that has been successful in previous work in delineating children’s category knowledge (e.g., Anglin 1977; Kyratzis et al., 1987; Nelson 1974, 1978). The goal here was to differentiate items produced in this task on the basis of their membership in different slot-filler categories, and to determine the extent to which 5- and 8-year-old children rely on such categories in their productions. In a similar task Kyratzis et al. (1987) showed that 4- and 7-year-olds cluster slot-filler items within the categories used here. Second, different instructions were used for children in different groups in
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order to determine whether slot-filler category cues would elicit category items more successfully for these children than would general category cues. Third, the sample used in this study differed from those in other studies in ways that allowed us to evaluate the effects of early school experience on the construction of category knowledge independent of age. All children were from a relatively low socioeconomic group in a large city. One group of 5-year-olds had had prior schooling experience, whereas members of the other kindergarten group were new to school. Thus, in addition to comparing 5-year-olds with 8year-olds, we could compare the two groups of 5-year-olds in terms of their prior school experience. In summary, the questions to be addressed in this study are the following: Do slot-filler category instructions aid younger children in producing category members? Do children organize category items in terms of slot fillers to a greater extent than in terms of conventional subcategories? Does exposure to category usage in school settings improve children’s ability to utilize category information? METHOD Subjects Three groups of children from a public school in a lower to lower-middle-class urban neighborhood participated in the study. One group of kindergarten children (Kl) consisting of 8 boys and 8 girls (M = 5 years, 4.6 months) had had no prior preschool experience. A second group of kindergarten children (K2) consisting of 7 boys and 7 girls (M = 5 years, 6 months) had previously attended day-care centers, nursery school, or Head Start programs. One group of second graders (M = 8 years, 1.7 months) included 8 boys and 8 girls. Procedure Children were interviewed individually in a quiet room at the school. They were randomly assigned to one of two conditions for the category production task. In the taxonomic condition children were asked to produce as many items as they could in three general categories: animals, clothing, and food. In the slot-filler condition, children were asked to name as many items as they could from categories within particular contexts, namely animals found at the zoo or on a farm; clothes worn inside or outside; foods eaten for breakfast or lunch. The instructions for the taxonomic condition were as follows: We are going to play a game. I am going to say the names of some things. After I say a name, you tell me all the things you can think of that belong with that name. For instance, I may say ‘tools’ and you might think of hammer, pliers, screwdriver, and lots of other things. Or I might say ‘toys.’ Can you tell me what you would think of if I say ‘toys?’ (child responds) Those are very good. You could probably
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435
have thought of (interviewer names other toys) or lots of other things too. Okay, now remember, each time I tell you a word, you say all the things you can think of that belong with the word I say. Try to name as many things as you can. Children in the slot-filler condition were given the same instructions except that the examples the interviewer used were “furniture you find in the living room” with couch, chair, and table as instances; and “toys you play with outside.” All children were encouraged, when necessary, to produce more items 7” with such prompts as “Can you think of any other RESULTS Group x Condition Analysis Responses that were inappropriate to a category or that repeated items already given were eliminated from the analysis. Then mean number of responses by each child in each category was tabulated and entered into a three-way repeated measures ANOVA (3 X 2 X 3) with group and condition as between-subject variables and category as the repeated measure. This analysis revealed a main effect of group, F(2,40) = 8.17, p < .OOl, a main effect of category, F(2,80) = 10.23, p < .002, a Group X Condition interaction, F(2, 40) = 4.82, p < .Ol, and a Group x Condition X Category interaction, F(4, 80) = 3.74, p < .007. Planned comparisons were used to test hypothesized differences. Cell means are displayed in Table 1, where the nature of the interactions is revealed. The main effect of group rests on the fact that, overall, the second graders produced more than the kindergartners, F( 1,40) = 12.23, p < .002, and the K2s produced more than the Kls, F(l, 40) = 3.58, p < .06. The main effect
Mean Number
TABLE 1 of Kerns Produced by Group, Condition
and Category
~wlory Group/Condition
N
Animals
Clothina
Food
M
Kl Taxonomic Slot-filler
8 8
5.88 6.25
4.00 9.12
7.88 10.87
5.92 8.75
K2 Taxonomic Slot-filler
7 7
8.86 11.29
7.57 12.43
9.43 19.00
8.62 14.24
Grade 2 Taxonomic Slot-filler
8 8
17.25 14.00
13.00 10.62
27.63 12.25
19.29 12.29
10.66 10.51
8.19 10.73
14.98 14.04
11.28 11.76
Mean Taxonomic Mean Slot-filler
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of category is found in the fact that, overall, more items were produced in the food category than in either of the others. (This is examined within grades and conditions later.) The interesting Group X Condition interaction reveals that, whereas the kindergarten groups produced more items in the slot-filler condition than in the taxonomic condition, the opposite was true for the second graders. (The condition contrast was not significant for Kl; for K2 it approached significance, F( 1, 40) = 3.16, p < .08; for Grade 2, F(1,40) = 5.60, p < .02. As shown in Table 1, this result was consistent for each category separately at each age, although only three of the individual condition post hoc comparisons within category were significant at the .05 level (clothing for the Kl group, p < .005; food for the K2 group, p < .Ol; and food for the Grade 2 group, p < 305). The Group X Condition X Category interaction can be seen in the consistent order of categories for both kindergarten groups in the slot-filler condition in number of items produced: Animals < Clothing < Food. The order of animals and clothing in the taxonomic condition is reversed, but this reversal is not significant. For the 7-year-olds, however, the order in the two conditions is quite different. It is especially noteworthy that in the slot-filler condition, secondgrade children actually produced fewer food items than did the children in K2 (although not significantly), whereas in the taxonomic condition they produced significantly more (almost 3 times as many), F( 1, 40) = 11.09, p < .002. Thus, the quantitative analysis of item responses provides initial answers to two of the questions posed. Taxonomic and slot-filler instructions had differential effects on item production, but those effects differed for the two ages. Younger children tended to produce more items when they were asked to produce items within each of two slot-filler categories than when they were asked to produce from the general taxonomic category. In contrast, older children produced significantly more items when they were given general taxonomic instructions than when their responses were directed to the narrow slot-filler categories. This finding suggests that their categories had become more general and complex, integrating items from a number of different slot-filler or other subcategories. Second, the two groups of kindergartners differed in their ability to produce category items in both conditions. Children in K2 who had had preschool experience produced more items than those without such experience. On the assumption that preschools emphasize categorical organization in their instructional programs, this finding supports the proposal that the acquisition of categorical knowledge is a function not only of individual cognitive development but of social-linguistic sharing of knowledge. The remaining analyses focused on the production and organization of items within categories. Category
Analyses
One indication of category knowledge is the number of inappropriate items produced. Table 2 shows the proportion of inappropriate items in each category
SCRIPT AND CATEGORY CUES
Proportion
TABLE 2 of Inappropriate
Animals Farm ZOO
.153
Clothing Inside Outside
.lll
Food Breakfast Lunch
M
Responses
K2
Kl Taxonomic
Slot-filler
Taxonomic
Grade 2 Slot-filler
Taxonomic
0 .170
.093
0
0
.I11
0
.060
.096
0
0 0
0
0
Slot-filler
.045
.645 .142
0
0
.119 .044 .I26
437
0 0 .040
.025 0 .017
in each condition for each age group. As is evident in this table, the largest number of inappropriate items was produced by the Kl group (overall M = 0.128). Even for this group, however, there were relatively few inappropriate items in any category except the farm animal category where 64.5% of their responses were judged inappropriate. The primary inappropriate items produced by the other groups were also in this category. It is not surprising that these lower income children from an inner-city environment might have difficulty with these items. Indeed, it seems plausible that this category did not in any way constitute a slot-filler category for them, there being little opportunity for them to derive it from real life experience or from books or television. In contrast, most of these children did have direct experience with zoo animals, because there was a nearby zoo that was regularly visited by school groups and presumably by many family groups as well. Again, the effects of prior preschool experience can be seen here in that neither the K2 nor the Grade 2 children produced many inappropriate items. Mean numbers of responses within each subcategory for the children in the slot-filler category condition are shown in Table 3. As seen in inappropriate responses, the children’s limited knowledge of farm animals is also evident here. There were no group differences in this subcategory. For zoo animals, both Grade 2 and K2 children produced significantly more responses than Kl children. The difference between farm and zoo animals was significant for the Grade 2 children, p = .003, but not for either of the other groups. For the clothing category, the primary findings of interest are that K2 children produced significantly @ < .05) more inside clothes than the Kl children, but there were no other significant differences between groups or categories. For the food categories, the notable finding is that the K2 group produced significantly more than either the Kl or the Grade 2 group in both the breakfast and lunch categories. The explanation for these differences is no doubt different
NELSON AND NELSON TABLE 3 Mean Numbw of items Produced in Slot-Hller Catagories Kl
K2
Grade 2
4.43 5.38
6.00 7.86
6.13 9.38
Clothing inside Outside
5.00 6.75
7.29 7.86
5.13 8.50
K2 > K1.p < .04 n.s.
Food Breakfast
5.71
9.00
6.13
Lunch
6.50
11.00
8.50
K2 > Kl, p < .Ol K2 > 2, p < .05 K2 > Kl, K2 > 2, p < .004
Animals Farm ZOO
Group Difference
. .
2sKl:;<.OO4 K2 > Kl, p < .05
in the two cases, however, as indicated by the different direction of results in the taxonomic condition. That is, it is clear that Grade 2 children know many more food items than they produced in this condition, whereas Kl children are not able to call upon more knowledge in the general category situation than in the restricted-meal context condition. Category Organization The organization of category members in terms of the order of their production can be considered, at least loosely, to reflect the underlying conceptual organization. Three different types of organization are considered here: typicality according to adult and child norms, hierarchical taxonomic subcategorization, and event-context organization. Typic&y. Typicality has emerged as an important basis for category organization since Rosch’s (1975) work. Categories are thought to be organized around the most typical members; thus, in category production tasks, more typical members arc generally produced first. More typical members are also expected to be learned before atypical ones. It might be questioned as to whether the children in this study, who represent a different population than that usually studied in developmental psychology (or cognitive psychology in general) display the same tendencies to produce typical items more frequently, or whether the items they do produce reveal different bases of typicality. Bjorklund, Thompson, and Ornstein (1983) gathered typicality ratings from middle-class kindergarten, third-grade and sixth-grade children, and adults in 12 natural language categories. Only one of these, clothing, overlapped with the categories in this study. Bjorklund et al. used subcategories of both food (fruits,
SCRIPT AND CATEGORY CUES
439
vegetables) and animals (dogs, birds). Nelson (1974) also used subcategories of food (fruits, vegetables). When the productions of the children in this study were compared in terms of frequency with the typicality ratings of the children in Bjorklund et al’s study for children in comparable age groups, there was considerable consistency, despite the difference in samples and tasks. The most typical items for the Syear-olds in the Bjorklund et al. study were (from most to least typical): pants, dress, shirt, coat, shoes, socks. The most frequent for the kindergartners in Condition 1 in the present study were (in order): pants, shirts, undershirt, sweater, socks, shoes, and dress. Five of the seven most frequently mentioned items were those rated most typical in the Bjorklund et al. study. The other two items (sweater and undershirt) were not included in their ratings. The kindergarten order is even more consistent with that produced by Syear-olds in the Nelson (1974) study. Those data were actually gathered in 1968 from uppermiddle-class children in California. The order in that study was: pants, shirt, dress, shoes, socks, shorts, and sweater. Similar results were found comparing Bjorklund et al’s typicality ratings by 8-year-olds with the present frequency data from second-grade children. The typicality ratings were: shirt, pants, dress, coat, shoes, and socks, from most to least typical. The frequency order in the present study was: shirt, (pants, shoes}, {dress, socks}, {sweater, skirt}, {blouse, undershirt}. Again, the order in the present study is even more consistent with Nelson’s (1974) order: pants, {shirt, socks}, shoes, dress, skirt, fiacket, underwear, hat}, and sweater. The only notable discrepancy in these lists is that the children in this study mention undershirt frequently (an item not ranked by the Bjorklund subjects), and the typicality ratings rank coat very typical, although that item is not mentioned either by the present subjects or the children in the Nelson (1974) study. Older children in the 1974 study did mention jacket and hat, however, among their most frequent items, and it should be noted that coats were infrequently needed or worn by children in the Los Angeles area. It might, therefore, be speculated that the absence of any outerwear among the most frequent items, even for the older children in this study, reflects their reliance upon relatively unintegrated context-determined organization. Comparison of the most frequently produced animal items in this study and in the Nelson (1974) study also showed similar orders. In particular, the younger children in this study produced zoo animals most frequently (elephant, giraffe, zebra, lion) as did the Nelson (1974) 5-year-olds (lion, giraffe, elephant, tiger). In contrast, the 8-year-olds in both studies included domestic animals (dog, cat) among the most frequent. Thus, the most frequently produced items in this study do seem to reflect the typicality structure of taxonomic categories to the same extent as other studies of young children have found, with some minor exceptions. However, these findings are based upon group data. To examine the other types of organization previously referred to, it is necessary to analyze the order of individual productions more carefully.
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NELSON AND NELSON
Organization by Conventional Subcategories and by Event-Context Categories In this section the output by each child for each category in the taxonomic condition is analyzed in terms of two contrasting methods of organization: conventional subcategories and event-context categories. For this purpose each item on each child’s list was coded in order of its output twice, once for the presumed event in which it was usually experienced, and once in terms of a conventional subcategorization system for foods, clothes, and animals. Table 4 lists the event contexts under each major category and the subcategories used for the conventional analysis. Some cautions should be noted with respect to the interpretation of these data. Assigning items to categories is not always straightforward; fuzzy boundaries and ambiguities exist for both types of organization. (However, very few ambiguous codings would have changed the numbers that enter into the following analyses.) In addition, the number of possible subcategories differs for the two types of organization and for different categories. Also, because the comparisons are between two types of analysis and not between conditions or groups, inferential statistics do not appear to be applicable. The analyses are nonetheless presented for their qualitative interest. TABLE 4 Subdivisions Used in Category Analysis Clothing
Animals
Food
Conventional Subcategories
mammals fish birds insects rodents0 marsupials amphibians reptiles worms mollusks
Context Subdivisions zoo animals farm animals pets/home woods/park animals found in water
meat
outerwear underwear sports footwear outdoorwear headwear nightwear accessories
vegetables fruit cereal pasta dairy beverages breads cakes condiments candy nuts soup manufactured foods
day/indoor clothes outdoor clothes sports clothes adult clothes nightclothes
aAlthough rodents are mammals, tinct group by lay people.
breakfast dinner lunch snack dessert
they tend to be treated as a dis-
441
SCRIPT AND CATEGORY CUES
Mean Number
TABLE 5 of Subdivisions and Category
Animals Conventional Kl K2 Grade 2
M
Clothes
Subcategories 1.57 2.29 3.75 2.54
Script Contexts Kl 2.57 K2 2.57 Grade 2 4.62 M 3.25
by Group
Food
3.29 3.43 4.12 3.61
3.88 3.86 8.62 4.78
1.71 2.29 2.75 2.25
2.29 2.57 4.0 2.95
The first analysis was in terms of how many subcategories a child included on the list and how many items came from each. Tables 5 and 6 display these figures. Table 5 shows the mean number of subcategories and the mean number of event contexts used at each grade for each main category. It can be seen that, in general, the number of subcategories increased in a more or less linear fashion with development for both types of subdivisions and for all three categories. The exceptions were the number of food categories, which did not differ between the two kindergarten groups, and the number of event categories, which also did not differ for these two groups. It appears that for both events and subcategories there are more subdivisions for food than for clothes; this outcome must be borne in mind in the following analysis. But note that for the animal category, there are fewer subcategories used than for food and clothing, whereas there are more event contexts used than for the others. This too will be important in subsequent analyses. The number of animal subcategories revealed here reflects the fact that although there are a large number of possible subdivisions, the vast majority of animals children named are in fact mammals, the large major subcategory of the animal class most familiar to them.
Number
TABLE 6 of ftems per Subdivision by Group and TVpe of Organization Conventionai
No. of Cat. Kl K2 Grade 2
M
2.90 3.19 4.83 3.64
Context
Items/Cat. 2.04 2.70 3.99 2.91
No. of Cat.
Items/Cat.
2.19 2.48 3.79 2.82
2.70 3.48 5.09 3.76
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Table 6 compares the number of categories with the number of items per category for each grade in each type of organization. Here it can be seen that if the lists are assumed to be organized in terms of conventional subcategories, they will contain a fairly large number of categories (ikf = 3.64) in comparison to the number of items in each category (M = 2.91). On the other hand, if the list is considered to be organized in terms of events, there will be relatively fewer contexts recalled (M = 2.82) compared to the number of items in each context (M = 3.76). The subcategory assumption suggests a rather shallow organization, the event-context assumption indicates a deeper organization (more items per node). Although these data cannot decide definitively between these two possibilities, further analysis sheds additional light on the matter. In this analysis the average length of run was computed for each list by context and by subcategory. The subdivisions were those shown in Table 4. A run consists of the consecutive occurrence of items from the same subdivision. In practice, the number of runs in a list is computed by counting the number of shifts from one subdivision to another (including the initial shift to begin naming). For example, in the list tiger, elephant, dog, cat, squirrel, there are two runs (4 mammals followed by 1 rodent) with a mean length of 2.5 in the conventional analysis, and three runs (2 zoo animals, 2 home animals, and 1 woods or park animal) with a mean length of 1.67 in the context analysis. Table 7 displays these results. Here it is apparent that length of run differs for the two types or organization. Runs by context overall average 3.15 compared to 2.5 1 for conventional categories, suggesting that the context organization has greater psychological reality or greater coherence. However, there are some peculiarities to be noted. First, the expected age difference is reversed, with the more advanced kindergarten group producing longer runs than the second graders. This is explicable in terms of the larger number of subdivisions second graders produce (see Tables 5 and 6) and in their larger number of items. Number of runs is a function of length of list and number of subcategories in addition to clustering of items within subcategories. Note again the difference between animals and the food and clothing categories. In the latter categories, runs are substantially longer for the context analysis TABLE 7 Mean Length of Runa by Type of Organization Conventional
Kl K2 Grade 2 M
Context
Animals
Clothina
Food
Animals
Clothina
Food
2.57 5.19 3.02 3.59
1.27 2.48 2.04 1.98
1.93 2.49 1.54 1.99
1.71 2.79 2.89 2.40
2.04 4.57 3.07 3.23
3.18 4.52 3.79 3.83
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than for the conventional, again suggesting that the context type of organization has greater psychological reality for the children. But for animals, the situation is reversed, with substantially longer runs for conventional subdivisions. Again, this is the result of children’s naming members of the mammal subcategory. Even though they know and can name other types (e.g., snake, fish, bird, rabbit, kangaroo), the majority of the most familiar animals, whether from farm, zoo, house, or park, belong to the mammal category. In this case, therefore, the context organization subdivides the category more finely than does the taxonomic organization (despite the greater potential for more subcategories for the taxonomic organization). The food category overall produced the longest runs. Children typically clustered together items from the same meal, often slot fillers such as meats, vegetables, pasta, or desserts. The fact that these were meal clusters rather than subcategory clusters is apparent in the fact that the context runs over all groups were almost twice as long as the conventional runs. GENERAL DISCUSSION This study has provided additional support for the proposal that young children’s superordinate categories are organized in terms of their event knowledge, in particular, in terms of slot-filler categories. It was shown first of all, that kindergarten children produced no more items on a category production task when they were allowed to produce category members freely from any context, than when they were given specific event-context cues. Indeed, they produced more in the latter condition (approaching significance), suggesting that their categories were organized according to specific events. Second graders, however, were found to produce significantly more items in the general category condition, suggesting that they had integrated the different event contexts into a larger structure. Children at both ages tended to produce items found to be most typical in other studies with children most frequently. Thus, the inner-city children in this study did not deviate from the category content-structure of the animals and clothes categories found with middle-class children. However, the food category used here could not be compared with the other groups, and this domain might well have revealed differences among groups based on different experiences. In addition, it was found that children in this study did not have a well-established farm animals category, reflecting their relatively restricted urban experience. Their experience with visits to the zoo, however, presumably provided the basis upon which they readily produced instances of typical zoo animals. A further restriction on their categories was seen in the low frequency of mention of outdoor clothing such as coats, in comparison to other studies. We do not believe that they did not have experience with coats, but rather that their categories were organized in a context-restricted way such that outdoor clothing was not entered into the general clothing category.
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When conventional subcategories were contrasted with context-based event categories in the analysis of the children’s output, it was found that for the clothes and food categories, context-based subdivisions produced more items per category and longer runs, whereas conventional categories produced more subcategories with fewer items per category and shorter runs. Thus, children’s clothes and food categories appeared to be best characterized in terms of eventbased organization. The animal category, however, produced both a larger number of subcategories and longer runs in the conventional analysis. It was noted that this was the result of the overwhelmingly dominant number of mammals in the lists. In the case of this category, the context-based organization divides the group more finely, but we cannot claim that either type of organization of animals has greater psychological validity because of the large and diverse membership in the mammal subclass. Theories of category knowledge acquisition outlined in the introduction do not address the issues of variation among children in categorical content and structure, or the basis for development of hierarchically organized categories. As we have seen, children’s first superordinate categories are not based so much upon common attributes, as Rosch’s (1975) work would suggest, but on common context. And in this study, as well as in Kyratzis et al. (1987), organization by context appears to be as much a characteristic of 7- and &year-olds’ categories as it is of 4- and Syear-olds.’ The fact that 8-year-olds in this study had more general and presumably better integrated categories than did the Syear-olds might suggest that they had advanced to a better understanding of class inclusion in the terms of Inhelder and Piaget (1964). However, there is no independent evidence of this, and an alternative possibility is that they have extended their understanding of the semantics of the superordinate terms to include what were initially context-restricted subdomains of knowledge. To the extent that this is the case, it suggests that education can play an important role in advancing children’s category knowledge. In contrast, both the natural abstraction view (represented in Rosch’s work) and the logical construction view (I&elder & Piaget) imply that category development proceeds according to an internal developmental timetable that is not amenable to external influence. A further finding in this study supports this suggestion. The low-income kindergarten children who had had preschool experience were able to produce more category items, and appeared to have those items organized better than those who had not had these experiences. This suggests that category knowledge is a joint function of the child’s own organization and exposure to the organization used by others, particularly in school settings. We can summarize these points in the following way: l
All children can be expected to categorize objects in their environments based on their own experience.
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Knowledge of the role of objects in familiar events provides a sound basis for such categorization. When experiences are widely shared across a culture, these categories will have similar content and structure, as found here for the clothes and animals categories. Nonetheless, there may be specific restrictions on content, as also found, and some spontaneously formed categories may vary across groups with varying experiences. Spontaneous categories become consolidated, integrated, and broadened in . contact with others, especially adults, who provide examples of the use of superordinate terms across specific contexts. Thus, children who initially do not include snacks in the food category, or who fail to include coats in the clothing category, may learn to extend their category knowledge when adults make such inclusion explicit. In this way, children may be led to construct hierarchical category structures that reproduce the taxonomies of the natural language system. Schools cannot expect the child to arrive at these on their own, or that they will come to school with a common organization of category knowledge even in familiar domains. However, even very young children with limited experience do have the basis for building general categories from their experientially derived knowledge representations. Recognizing both the context-specific basis of their categorical structures and the possibility of their integration into larger taxonomic domains is important to the task of bringing all children into a common universe of discourse about even the most mundane categorical knowledge systems. REFERENCES Anglin,J.M.
(1977). Word, object, and concephud developmenr. New York: Norton. Bjorklund, D.F., Thompson, B.E., & Ornstein, P.A. (1983). Developmental trends in children’s typicality judgments. Behavioral Research Methods and Instrumentarion, IS, 350-356. Bruner, J.S., Olver, R.R., & Greenfield, P.M. (1966). Studies in cognitive growth. New York: Wiley. Horton, M.S., & Markman, E.M. (1980). Developmental differences in the acquisition of basic and superordinate categories. Child Developmen& 51, 708-719. Inhelder, B., & Piaget, J. (1964). The early growth oflogic in the child. New York: Harper & Row. Krackow, E., & Blew&, P. (1989, March). What derermines order of acquisition of taxonomic relationships? Paper presented at the annual meeting of the Southeastern Psychological Association, Washington, DC. Kyratzis, A., Lucariello, J., Nelson, K., & Greenstein, C. (1987, April). The schematic to raxorwmic shifr revisited: Category construction in preschool nnd school-aged children. Poster presented at the biennial meeting of the Society for Research in Child Development, Baltimore, MD. Lucariello, J., & Nelson, K. (1985). Slot-filler categories as memory organizers for young children. Developmenral Psychology, 21, 272-282.
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Lucariello, J., & Nelson, K. (1986). Context effects on lexical specificity in maternal and child discourse. Journal of Child Language, 13, 501-522. Nelson, K. (1973). Some evidence for the cognitive primacy of categorization and its timctional basis. Merrill-Palmer Quarterly Journal of Behavior and Development, 19, 21-39. Nelson, K. (1974). Variations in children’s concepts by age and category. CM-l Development, 45, 577-584.
Nelson, K. (1978). Semantic development and the development of semantic memory. In K.E. Nelson (Ed.), Children’s language. New York: Gardner Press. Nelson, K. (1985). Making sense: The acquisition of shared meaning. New York: Academic. Nelson, K. (1986). Evenr knowledge: Structure andfunction in development. Hillsdale, NJ: Brlbaum. Nelson, K. (1988). Where do taxonomic categories come from? Human Development, 31, 3-10. Rosch, E. (1975). Cognitive representations of semantic categories. Journal of Experimental Psychology: General, 104, 192-233. Rosch, E., Mervis, C.B., Gray, W.D., Johnson, D.M., & Boyes-Braem, P. (1976). Basic objects in natural categories. Cognitive Psychology, 8, 382-439. Rosner, S.R., & Smick, C. (1989, April). Cueing maintenance of slot-filler and taxonomic categories. Poster presented at the biennial meeting of the Society for Research in Child Development, Kansas City, MO. Saltx, E., Soller, E., & Sigel, I.E. (1972). The development of natural language concepts. Child Development, 43, 1191-1202. Smith, CL. (1979). Children’s understanding of natural language hierarchies. Journal of Experimental Child Psychology,
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