Developmental Differences in Preferences for Using Color, Size, and Location Information to Disambiguate Hiding Places

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1 JOURNAL OF COGNITION AND DEVELOPMENT, 8(4), Copyright 2007, Lawrence Erlbaum Associates, Inc. Developmental Differences in Preferences for Using Color, Size, and Location Information to Disambiguate Hiding Places Jodie M. Plumert and Penney Nichols-Whitehead The University of Iowa We conducted four experiments to examine developmental differences in preferences for using color, size, and location information to disambiguate hiding places. Three- and 4-year-olds and adults described how to find a miniature mouse that was hidden in one of two highly similar small objects in a dollhouse. In Experiment 1, the hiding places could be disambiguated by either color or location. Three-year-olds preferred color to location whereas adults preferred location to color information. Four-year-olds showed no preferences. In Experiment 2, the hiding places could be disambiguated by either size or location. Four-year-olds preferred size to location information whereas adults preferred location to size information. Three-year-olds showed no preferences. In Experiment 3, the hiding places could be disambiguated by either color or size information. Adults preferred size to color information, but 3- and 4-year-olds showed no preference for either type of information. Experiment 4 revealed that when only location information was available for disambiguating the hiding places, 4-year-olds referred to disambiguating location information on a significantly greater percentage of trials than did 3-year-olds. Discussion focuses on the role of relational complexity and pragmatic knowledge in producing preferences for disambiguating information in spatial communication tasks. Children and adults alike are frequently asked to describe the whereabouts of missing objects. One of the challenges speakers confront when describing object locations is disambiguating between potentially confusable places (e.g., two or more couches in a house). Typically, several types of information are available for dis- Correspondence should be sent to Jodie M. Plumert, Department of Psychology, 11 SSH East, University of Iowa, Iowa City, IA jodie-plumert@uiowa.edu

2 428 PLUMERT, NICHOLS-WHITEHEAD ambiguating hiding places. For example, one might distinguish the target place (e.g., a couch) from other confusable places by referring to location information (e.g., The shoes are by the couch in the living room ), color information (e.g., The shoes are by the green couch ), or size information ( The shoes are by the little couch ). In nearly all studies of the development of spatial communication, however, location information is the only type of information available for disambiguating hiding places (Plumert, Ewert, & Spear, 1995; Plumert & Hawkins, 2001; Plumert & Nichols-Whitehead, 1996; for an exception see Craton, Elicker, Plumert, & Pick, 1990). Thus, little is known about young children s preferences for disambiguating information when multiple sources of information are available. The goal of this investigation was to examine developmental differences in preferences for disambiguating information when multiple sources of information were available for distinguishing between two highly similar hiding places. What factors might play a role in governing preferences for disambiguating information? One possibility is the complexity of the disambiguating information. Consider a situation in which a child asks a 4-year-old sibling where a missing toy is located. In the playroom there are two boxes, one of which contains the missing toy. One way for the sibling to disambiguate the two boxes is by referring to location information (e.g., It s in the box that s on the table ). Another way for the sibling to disambiguate the two boxes is by referring to color information (e.g., It s in the box that s yellow ). To convey disambiguating location information, the sibling has to compare the spatial relations between the two sets of small and large landmarks (e.g., a box on the table vs. a box on the couch). To convey disambiguating color information, the sibling has to compare the colors of the two small landmarks (e.g., the yellow box vs. the red box). Clearly, comparing two relations between objects is more complex than comparing the properties of two objects. Young children may be more likely to choose a simpler source of disambiguating information over a more complex source of disambiguating information when both are available. This idea is consistent with previous research on developmental changes in young children s use of relational information (Andrews & Halford, 2002; Genter, 1988; Gentner & Ratterman, 1991; Goswami, 1989; Halford, Andrews, Dalton, Boag, & Zielinski, 2002; Halford, Wilson, & Phillips, 1998; Ratterman & Gentner, 1998). Research on analogical reasoning, conducted by Gentner and her colleagues, has shown that young children have difficulty making comparisons based solely on relational information (Gentner, 1988; Gentner & Ratterman, 1991; Goswami, 1989; Ratterman & Gentner, 1998). According to Gentner (1988), children between the ages of 3 and 5 undergo a shift from using object similarity to using relational similarity to solve analogical reasoning tasks. In one study, for example, children were presented with two arrays of objects arranged in an order of decreasing size (Gentner & Ratterman, 1991). Object similarity and relational similarity were placed in direct competition with each other by making the first ob-

3 PREFERENCES FOR DISAMBIGUATING INFORMATION 429 ject in one array identical in size to the second object in the other array. Children first watched as the experimenter placed a sticker under an object in one of the arrays. Children then searched for a sticker under the corresponding object in the second array. Five-year-olds preferred the relational match whereas 3-year-olds preferred the object match. These findings are consistent with the idea that children s understanding and use of relational information undergoes significant change over the preschool years. Work by Halford and his colleagues also supports the idea that relational complexity plays an important role in children s performance on a variety of reasoning tasks (Andrews & Halford, 2002, Halford et al., 1998, 2002). According to Halford, much of the developmental change seen in children s reasoning skills can be explained by changes in the ability to process more complex relations. Relational complexity is defined as the number of arguments or entities that must be simultaneously considered to solve a problem. Unary relations have a single argument as in The dog is brown. Binary relations have two arguments as in The dog is bigger than the cat. Ternary relations have three arguments as in If Mary is taller than Sue and Sue is taller than Ellen, then Mary is taller than Ellen. According to Halford, unary relations can be processed at approximately one year of age, binary relations at two years of age, and ternary relations at five years of age. How might this framework apply to the problem of disambiguating two confusable hiding places? Consider two hiding places (one containing the missing object) that differ in color, size, and location. To distinguish the two hiding places using color, the speaker need only consider two unary relations (e.g., the red box vs. the yellow box). To distinguish the two hiding places using size, the speaker must consider a single binary relation between two objects (e.g., the big box vs. the small box). To distinguish the two hiding places using location, the speaker must consider two binary relations (e.g., the box on the table vs. the box on the couch). According to this analysis, location information involves more complex relational information as compared to color or size information. As a result, young children may avoid location information when other, less complex choices are available. A second factor that may govern the choice of disambiguating information is pragmatic knowledge. Consider again the situation in which a child asks his 4-year-old sibling where a missing toy is located. Given that the listener s goal is to find the missing toy, one might expect that the speaker would favor location information over other types of competing information. Implicitly, location information may be more closely matched to the listener s goal of locating the missing toy than is color or size information. Thus, pragmatic knowledge about the listener s goal may also play a role in guiding the speaker s choice of disambiguating information. Adults appear to be quite sensitive to the goals of the listener in communication tasks (Klabunde & Porzel, 1998; Plumert, Carswell, DeVet, & Ihrig, 1995; Plumert, Spalding, & Nichols-Whitehead, 2001, Russell & Schober, 1999;

4 430 PLUMERT, NICHOLS-WHITEHEAD Schober, 1995). For example, Plumert et al. (1995, 2001) have shown that the ordering of spatial information in directions for finding missing objects appears to be governed by the needs of the listener. In particular, adults order landmarks and regions from large to small when giving directions for finding hidden objects (e.g., Go down two flights, turn right, on the right side of the room against the back wall there is a table, under the table is a box full of newspapers, under a small stack is the chips. ). Why might this be the case? When the task is to give directions to someone else about how to find something, the goal is to get the listener from his or her present position to the location of the object. Thus, speakers may feel constrained to convey units of spatial information in the order in which the listener will encounter them. Movement through the space generally dictates that the listener encounters spatial units (i.e., landmarks and regions) in an order of decreasing size. That is, the listener must reach the floor before the room, and once inside the room, is likely to notice large landmarks before small landmarks. The idea that adults order spatial information from large to small in their directions to accommodate the needs of the listener is further supported by research showing that adults access spatial information from memory in an order of small to large (Plumert et al., 2001). In other words, adults are faster to verify sentences describing object locations when the spatial units are ordered from smallest to largest, indicating that they recall object locations by starting at the most specific level of the hierarchy. This suggests that they reorder spatial information from large to small in their directions to accommodate the needs of the listener. What does previous research tell us about whether young children take into account the goals or intentions of the listener? Research on pragmatic development has clearly shown that preschoolers take into account some aspects of the listener in forming their utterances (e.g., Maratsos, 1973; Shatz & Gelman, 1973). For example, 3- to 5-year-olds used far less pointing in a referential communication task when the listener was blindfolded than when the listener was not blindfolded. Likewise, Shatz and Gelman (1973) found that 4-year-olds used less complex speech when talking with 2-year-olds than when talking with their peers or mothers. Thus, preschoolers respond to highly observable characteristics of the listener by modifying their speech to better fit the listener s needs. Other research, however, has shown that young children have difficulty taking into account less observable characteristics of the listener such as goals or intentions (e.g., Abbeduto, Nuccio, Al-Mabuk, Rotto, & Maas, 1992). Such difficulty could inhibit preschoolers use of location information (relative to adults ) to disambiguate hiding places, particularly when simpler types of disambiguating information (e.g., color and size) are available. The goal of this investigation was to examine developmental differences in preferences for location, color, and size information for disambiguating hiding places. Three- and 4-year-olds and a comparison group of adults described how to find a miniature mouse hidden in a small dollhouse. Several pairs of small objects

5 PREFERENCES FOR DISAMBIGUATING INFORMATION 431 served as hiding places (e.g., bags, boxes, plants). The mouse was always hidden with one member of the pair, while the other member remained empty. Thus, in order to communicate clearly about the hiding place of the mouse, participants had to disambiguate the target-hiding place from the nontarget hiding place. In Experiment 1, the hiding place could be disambiguated by referring to either color ( It s in the bag with the red stripe ) or location ( It s in the bag next to the couch ) information. Based on young children s difficulty with using more complex relational information, we expected that 3- and 4-year-olds would prefer color to location information. In contrast, we expected that adults would prefer location to color information based on their greater sensitivity to the pragmatics of the task. In Experiment 2, the hiding places could be disambiguated by referring to either size ( It s in the big bag ) or location ( It s in the bag next to the couch ). We expected that 3- and 4-year-olds would prefer size to location information, but that adults again would prefer location information. In Experiment 3, we contrasted disambiguating color and size information to determine whether children and adults exhibited a preference for either of these two types of nonspatial information. Finally, in Experiment 4, we examined 3- and 4-year-olds references to location information when only location information was available to disambiguate the hiding places. EXPERIMENT 1 Method Participants. Participants were 42 three-year-olds, four-year-olds, and adults from predominantly middle- to upper middle-class Caucasian families. The mean ages were 3 years and 10 months (range = 3; 9 3;11 ), 4 years and 10 months (range = 4;9 to 4;11), and 19 years and 3 months (range = 18;1 20;0). There were 7 boys and 7 girls in the 3-year-old group, 8 boys and 6 girls in the 4-year-old group, and 7 men and 7 women in the adult group. The children were recruited from a child research participant database. Parents received a letter describing the study followed by a phone call inviting their child to participate. The adults participated to fulfill research credit in an introductory psychology course. Apparatus and Materials. A 56-cm wide cm deep cm high model room was used as the experimental space (see Figure 1). A miniature mouse served as the hidden object and a 3.8-cm high troll figure served as the listener. Within the model room there were eight pairs of small objects that served as hiding places. These included pillows, bags, trashcans, towels, hats, pots, plants, and shoes. The two members of each pair of small objects differed by a single color feature. There was a pillow with a red heart and a pillow with a yellow heart, a grocery bag with red lettering and a grocery bag with green

6 432 PLUMERT, NICHOLS-WHITEHEAD FIGURE 1 Dollhouse used as the experimental space. lettering, a towel with a yellow ribbon and a towel with a blue ribbon, a hat with a blue ribbon and a hat with a green ribbon, a pot with a red lid and a pot with a blue lid, a plant with a red striped pot and a plant with a blue striped pot, and a shoe with yellow stripes and a shoe with green stripes. Eight pieces of furniture served as landmarks; a TV, chair, piano, couch, stove, table, refrigerator, and a sink, for one pair of small objects. One member of the pair was placed on the piece of furniture, and the other was placed next to and touching the furniture item. Thus, the target member of the pair (i.e., the hiding place) could be disambiguated from the nontarget member by using color information (e.g., The hat with the blue ribbon. ) or location information (e.g., The hat on the chair. ). A Plexiglas cover that could be raised and lowered over the front of the house was used to prevent children from pointing directly at hiding places or retrieving the mouse before they described its hiding place. The dollhouse was placed on a low table and the child was always seated directly in front of it. The experimenter sat on the child s left side. The entire session was videotaped via a Panasonic camcorder positioned above the dollhouse.

7 PREFERENCES FOR DISAMBIGUATING INFORMATION 433 Design and Procedure Familiarization. Participants were tested individually in the laboratory. During familiarization with the dollhouse, participants were shown the troll figure and told that they would be giving directions to the troll about how to find a mouse in the dollhouse. Participants were then asked to name each object in the dollhouse. The experimenter pointed out the objects in the dollhouse in a random order with the constraint that she pointed out both members of each pair of small objects together. That is, after the participant named the first member of a pair, the experimenter would say, Did you see there is another, just like it right here? This was done to ensure that participants were aware of the pairs of small objects. If participants could not name an item, the experimenter supplied the label and later questioned them about that item to make sure they remembered its name. Practice trial. After familiarization, children were instructed that the troll would hide behind the dollhouse while they helped the experimenter hide the mouse. The troll would then come back to the front of the house, and they would try to tell the troll exactly how to find the mouse. Children first were given a practice trial in which they hid the mouse under the couch and were asked to describe how to find the mouse to the troll. This practice trial was designed to engage children in the task of verbally describing a hiding place and the practice trial did not provide children with experience distinguishing between two highly confusable hiding places because there was only one couch in the dollhouse. After completing the practice trial, children were praised for their effort (most children had no trouble describing the hiding place). Test trials. There were eight test trials, each involving one of the eight target small objects. The member of each pair that served as the hiding place was counterbalanced across participants. Four of the target hiding places involved the spatial relation of support (i.e., on the furniture landmark) and four involved the relation of proximity (i.e., next to and touching the furniture landmark). The order in which participants described the hiding places was randomized across subjects. For each trial, the experimenter put the troll behind the dollhouse and then touched the hiding place with a pencil and instructed the participant: Hide the mouse right there. For all hiding places, the mouse was completely hidden from view. After the mouse was hidden, the experimenter closed the cover and reminded children not to point to the mouse s hiding place. Children were also instructed to either cross their arms or sit on their hands. The experimenter then brought the troll to the front of the dollhouse and said, Can you tell the troll exactly how to find the mouse? The delay between when participants finished hiding the mouse and when the experimenter finished asking them to describe how to find the mouse was approximately 10 s. If the participant s initial description was inadequate to spec-

8 434 PLUMERT, NICHOLS-WHITEHEAD ify how to find the mouse, the experimenter would give a series of structured prompts to elicit more information. The first prompt was always, Can you tell the troll anything else about how to find the mouse? If the participant only responded with a reference to the small object, (e.g., It s under the hat. ), the experimenter followed up the first prompt with, I see two hats. Can you tell the troll anything else about how to find the mouse? If the child only responded with a reference to the landmark (e.g., It s by the couch ), the experimenter would say, I see two things with the couch. Can you tell the troll anything else about how to find the mouse? The trial ended when the participant provided sufficient information to specify the hiding place of the mouse or the participant failed to provide sufficient information in response to the series of structured prompts. When participants provided sufficient disambiguating information, the experimenter searched for the mouse in the correct place. When participants failed to provide sufficient disambiguating information, however, the experimenter searched in the wrong hiding place (i.e., the wrong member of the pair of small objects). Upon failing to find the mouse, the experimenter would say, Hmmm, it s not here, and proceed to look in the correct hiding place. This aspect of the procedure was designed to further encourage children to provide disambiguating information. Color production test. Participants were given a color production test after the communication task to determine whether they could verbally disambiguate between objects on the basis of the colors used in this experiment (i.e., red, yellow, blue, and green). A 10.2 cm cm piece of colored construction paper was held up and the participant was asked to name the color. All children were able to name the colors. At the end of the session, children were allowed to select two prizes and were thanked for their participation. Adults were debriefed about the nature of the experiment and thanked for their participation. Coding and Measures All verbalizations were transcribed verbatim and coded for presence or absence of the targeted information. The following aspects of participants descriptions were coded: a) small object references, b) location references, and c) color references. All descriptions were coded, including those provided after the specific prompt. A small object reference was coded as present when children mentioned or described the object with which the mouse was hidden (e.g., The mouse is in the bag or The mouse is in the grocery thing ). Participants received a small object reference score representing the percentage of trials in which they mentioned the small object. A location reference was coded as present when children mentioned or described the spatial relation between the small object and a landmark (e.g., the shoe by the piano or the pot on the floor ). Although children sometimes re-

9 PREFERENCES FOR DISAMBIGUATING INFORMATION 435 ferred to the small object and a landmark in a single description, the two were often produced separately. For example, it was not uncommon for children to give the small object spontaneously (e.g., it s in the shoe ), and to provide a disambiguating landmark in response to a prompt (e.g., the one by the piano ). Children were given credit for a location reference in either case. Children received a location reference score that represented the percentage of trials in which they mentioned location information. A color reference was coded as present when children mentioned color information that differentiated the target from the nontarget member of the small object pair (e.g., the hat with the blue ribbon or the blue hat ). Again, although children sometimes referred to the small object and its color in a single description, the two were often produced separately. Children were given credit for a color reference in either case. Children received a color reference score that represented the percentage of trials in which they referred to the color of the target small object. Intercoder reliabilities were calculated on nine randomly selected participants (three from each age group). Exact percent agreement for small object references, location references, and color references were 100, 97, and 97%, respectively. Results References to the Small Object As expected, children and adults alike usually referred to the small object when describing how to find the mouse. On average, 3-year-olds, 4-year-olds, and adults referred to the small object on 96% (SD = 12%), 97% (SD = 7%), and 100% (SD = 0%), of trials, respectively. A one-way Analysis of Variance (ANOVA) revealed that thepercentageofsmallobjectreferencesdidnotdifferbyage,f(2,39)=.90,ns. References to Disambiguating Location and Color Information Were there developmental differences in preferences for using location and color information to disambiguate hiding places? We first examined the percentage of trials on which participants provided either kind of disambiguating information as an indication of their overall success in the task. Prior to prompting, 3-year-olds, 4-year-olds, and adults provided some form of disambiguating information on 62% (SD = 27%), 55% (SD = 36%), and 100% of trials, respectively. After prompting, 3-year-olds, 4-year-olds, and adults provided some form of disambiguating information on 80% (SD = 18.5%), 84% (SD = 29%), and 100% (SD = 0%) of trials, respectively. A one-way ANOVA on references to disambiguating information after prompting with age as a factor was significant, F (2, 39) = 4.17, p <.05. Post-hoc analyses using Tukey s Honestly Significant Difference (HSD) revealed that adults provided disambiguating information on a significantly greater

10 436 PLUMERT, NICHOLS-WHITEHEAD percentage of trials than did the 3-year-olds. The 4-year-olds and adults did not differ significantly, nor did the 3- and 4-year-olds. To examine whether there were developmental differences in preferences for the two types of disambiguating information, we entered the percentage of location references and color references into an Age (3 yrs vs. 4 yrs vs. adults) 3 Information Type (location vs. color) repeated measures ANOVA with the first factor as a between-subjects variable and the second as a within-subjects variable. 1 This analysis yielded a significant effect of age, F (2, 39) = 4.32, p <.05, and a significant Age 3 Information Type interaction, F (2, 39) = 13.31, p < We examined the Age 3 Information Type interaction in two ways. First, we examined whether there was a preference for either type of disambiguating information at each age. As shown in Figure 2, simple effects test revealed a significant preference for color over location information for 3-year-olds, F (1, 13) = 5.08, p <.05, no significant preference for either type of information for 4-year-olds, F (1, 13) =.53, ns, and a significant preference for location over color information for adults, F (1, 13) = 33.88, p < Thus, when both location and color information were available for disambiguating the hiding place, adults exhibited a clear preference for location information. In contrast, 3-year-olds exhibited a clear preference for color information. Four-year-olds did not exhibit a significant preference for either type of information. Second, we examined whether there were age differences in the percentage of references to each type of information. As shown in Figure 2, there was a significant effect of age for references to disambiguating location information, F (2, 39) = 21.93, p <.0001, and a significant effect of age for references to disambiguating color information, F (2, 39) = 3.25, p <.05. Follow-up analyses using Tukey s HSD test revealed that adults referred to location information on a much higher percentage of trials than did 3- and 4-year-olds. In fact, adults referred to location information on nearly all trials, whereas children referred to location information on less than half of all trials. Follow-up analyses also revealed that 3-year-olds referred to color information on a higher percentage of trials than did adults. Four-year-olds did not differ significantly from either 3-year-olds or adults. Thus, references to disambiguating location information increased with age and references to disambiguating color information decreased with age. Use of redundant disambiguating information. We also examined whether there were age differences in the propensity to provide redundant disambiguating information. In other words, when children and adults provided one type of disam- 1 Each of the percentage scores entered into the analyses was free to independently vary between zero and 100%. That is, use of one type of information did not preclude the use of the other type of information. Potentially, a participant could have scores of 100% for both types of information. Thus, the percentage scores were statistically independent.

11 PREFERENCES FOR DISAMBIGUATING INFORMATION 437 FIGURE 2 References to disambiguating color and location information by age. biguating information, did they also sometimes provide the other type of disambiguating information? To address this question, the percentage of trials in which participants referred to both location and color information (e.g., under the hat with the blue stripe on the chair ) was entered into a one-way ANOVA with age as a between-subjects factor. Although there was some tendency for adults to provide more redundant information than children, this analysis did not yield a significant effect of age, F (2, 39) = 1.74, ns. Three-year-olds, 4-year-olds, and adults provided redundant location and color information on 9% (SD = 19%), 12% (SD = 18%), and 25% (SD = 33%) of trials, respectively. Individual patterns of performance. Finally, we examined individual patterns of performance to explore whether participants in each age group showed strong biases toward color or location information. Across the eight test trials, we calculated the percentage of participants who referred only to color or only to location information, or referred at least once to each type of information (but not necessarily in the same trial). As shown in Table 1, about half of the 3-year-olds showed a strong bias toward color (they never mentioned location on any trial) and half of the adults showed a strong bias toward location (they never mentioned color on any trial). The remaining 3-year-olds and adults used some of each type of in-

12 438 PLUMERT, NICHOLS-WHITEHEAD TABLE 1 Number of Participants Referring to Only Color, Only Location, or to Color and Location Across Trials Information Type Age Group Color Only Location Only Color and Location 3-year-olds 6 (43%) 2 (14%) 6 (43%) 4-year-olds 3 (21%) 3 (21%) 8 (57%) Adults 0 (0%) 7 (50%) 7 (50%) formation. The 4-year-olds fell somewhere in between, with some exhibiting a strong bias toward color and some exhibiting a strong bias toward location, but over half using some of each type of information. Thus, the individual patterns of performance generally mirrored the patterns of group performance above. Discussion The results of this experiment clearly show that when both location and color information were available for disambiguating hiding places, 3-year-olds preferred to use color over location information and adults preferred to use location over color information. Four-year-olds showed no significant preference for either source of information. Moreover, children s use of location information to disambiguate hiding places was much lower than that of adults. Adults used location information on virtually all trials whereas children used location information on less than half of the trials. What accounts for this developmental difference in the use of disambiguating location information? We hypothesize that adults prefer location information to other types of information because they are sensitive to the pragmatics of the task. In other words, location information is more closely matched the goal of finding the hidden mouse than did color information. We hypothesize that young children s preferences are driven by the complexity of the disambiguating information. That is, young children were less likely to use disambiguating location information than were adults because location information involved making complex relational comparisons, with which they might have difficulty. In Experiment 2, we tested whether young children avoid using disambiguating location information because they have difficulty with making relational comparisons in general or whether their avoidance of disambiguating location information stems more specifically from difficulty with making complex relational comparisons. In this experiment, we pitted disambiguating size information (e.g., It s under the big hat ) against disambiguating location information (e.g., It s under the

13 PREFERENCES FOR DISAMBIGUATING INFORMATION 439 hat next to the couch ). Using size information to disambiguate two hiding places requires that children compare the single, binary relation between the two hats (e.g., the big hat vs. the little hat). Using location information to disambiguate two hiding places requires that children compare the binary relation between the target hat and its corresponding landmark (e.g., the couch) to the binary relation between the nontarget hat and its corresponding landmark (e.g., the TV). Within Halford s framework, considering two binary relations is more complex than considering a single binary relation. If young children s difficulty with using disambiguating location information stems from difficulty with more complex relations, then they should show a preference for size information over location information. In contrast, adults should show a preference for location information over size information based on their sensitivity to the pragmatics of the task. EXPERIMENT 2 Method Participants Participants were 42 each of three-year-olds, four-year-olds, and adults from predominantly middle- to upper middle-class Caucasian families. The mean ages were 3 years and 7 months (range = 3;6 3;8), 4 years and 6 months (range = 4;3 4;10), and 20 years and 4 months (range = 18;9 27;7). There were 8 boys and 6 girls in the 3-year-old group, 7 boys and 7 girls in the 4-year-old group, and 7 men and 7 women in the adult group. The children and adults were recruited in the same manner as in Experiment 1. Apparatus and Materials The same dollhouse and furniture landmarks were used as in Experiment 1. The eight pairs of small objects included bags, pillows, pots, plants, baskets, boxes, hats, and pitchers. The two members of each small object pair were identical except that one was large and one was small. The large object was approximately 1.5 times the size of the small object (range = ). Design and Procedure All aspects of the procedure were identical to those used in Experiment 1. After the communication task, we gave participants a size production test to determine whether they could verbally distinguish between objects on the basis of size. Participants were shown a novel pair of objects that were identical except for size. The experimenter said, See these? Can you tell me about them? If the participant did not spontaneously volunteer information about the size difference, the experi-

14 440 PLUMERT, NICHOLS-WHITEHEAD menter said, Can you tell me how they are different? This procedure was repeated for a second pair of novel objects. All children were able to verbally note the size difference between the objects. Coding and Measures The coding and measures were identical to those used in Experiment 1 except that rather than color references; we coded size references in addition to location references and small object references. A size reference was coded as present when participants mentioned something about the size of the target small object (e.g., the big pillow or not the little pillow, the big pillow ). Intercoder reliabilities were calculated on nine randomly selected participants (three from each age group). Exact percent agreement for small object references, location references, and size references was 100%. Results References to the Small Object As in Experiment 1, children and adults alike almost always referred to the small object when describing how to find the mouse. On average, 3-year-olds, 4-year-olds, and adults referred to the small object on 99% (SD = 3%), 100% (SD = 0%), and 100% (SD = 0%) of trials, respectively. A one-way ANOVA revealed that the percentage of small object references did not differ by age, F (2, 39) = 1.00, ns. References to Disambiguating Location and Size Information The primary question of interest was whether there were developmental differences in preferences for using location and size information to disambiguate the target from the nontarget hiding place. We first examined the percentage of trials on which participants provided either kind of disambiguating information as an indication of their overall success in the task. Prior to prompting, 3-year-olds, 4-year-olds, and adults provided some form of disambiguating information on 59% (SD = 31%), 62% (SD = 32%), and 100% of trials, respectively. After prompting, however, 3-year-olds, 4-year-olds, and adults provided some form of disambiguating information on 83% (SD = 28%), 88% (SD = 15%), and 100% of trials, respectively. A one-way ANOVA on references to disambiguating information after prompting with age as a factor was marginally significant, F (2, 39) = 3.17, p =.053. To examine whether there were developmental differences in preferences for the two types of disambiguating information, we entered the percentage of location references and size references into an Age (3) 3 Information Type (2) repeated measures ANOVA with the first factor as a between-subjects variable and

15 PREFERENCES FOR DISAMBIGUATING INFORMATION 441 the second as a within-subjects variable. This analysis yielded a significant effect of age, F (2, 39) = 12.51, p <.0001, and a significant Age 3 Information Type interaction, F (2, 39) = 11.27, p <.001. We examined the Age 3 Information Type interaction in two ways. First, we examined whether there was a preference for either type of disambiguating information at each age. As shown in Figure 3, simple effects tests revealed no significant preference for location or size for 3-year-olds, F (1, 13) =.06, ns, a significant preference for size over location information for 4-year-olds, F (1, 13) = 11.95, p <.01, and a significant preference for location over size information for adults, F (1, 13) = 24.21, p <.001. Thus, when both location and size information were available for disambiguating the hiding place, adults exhibited a clear preference for location information. In contrast, 4-year-olds exhibited a clear preference for size information. Three-year-olds did not exhibit a significant preference for either type of information. Second, we examined whether there were age differences in the percentage of references to each type of information. As shown in Figure 3, there was a significant effect of age for references to disambiguating location information, F (2, 39) = 23.75, p <.0001, and a significant effect of age for references to disambiguating size information, F (2, 39) = 3.78, p <.05. Follow-up analyses revealed that adults referred to location information on a much higher percentage of trials than did 3- and 4-year-olds. In addition, 3-year-olds referred to location information on a higher percentage of trials than did 4-year-olds. As in Experiment 1, adults referred to location information on nearly all trials whereas chil- FIGURE 3 References to disambiguating size and location information by age.

16 442 PLUMERT, NICHOLS-WHITEHEAD dren referred to location information on less than half of all trials. Follow-up analyses also revealed that 4-year-olds referred to size information on a higher percentage of trials than did adults. Three-year-olds did not differ significantly from either 4-year-olds or adults. Use of redundant disambiguating information We also examined whether there were age differences in the propensity to provide redundant disambiguating information (i.e., both location and size information). To address this issue, the percentage of trials in which participants referred to both location and size information (e.g., under the big box on the chair ) was entered into a one-way ANOVA with age as a between-subjects factor. This analysis yielded a significant effect of age, F (2, 39) = 9.96, p <.001. Follow-up analyses revealed that adults provided redundant information on a significantly greater percentage of trials than did 3- and 4-year-olds. Three-year-olds, 4-year-olds, and adults provided redundant location and size information on 1% (SD = 4%), 2% (SD = 5%), and 32% (SD = 36%) of trials, respectively. Individual patterns of performance. Finally, we examined individual patterns of performance to explore whether participants in each age group showed strong biases toward size or location information. Across the eight test trials, we calculated the percentage of participants who referred only to size or only to location information, or referred at least once to both types of information (but not necessarily in the same trial). As shown in Table 2, nearly two-thirds of the 4-year-olds showed a strong bias toward size (they never mentioned location on any trial). In contrast to Experiment 1, however, relatively few of the adults showed a strong bias toward location (they never mentioned size on any trial). Most of the adults referred to size on at least one trial, although none of them referred exclusively to size whereas some referred exclusively to location. The 3-year-olds were about evenly split between using size exclusively, location exclusively, or referring to both size and location. Thus, although the group data show a strong bias toward TABLE 2 Number of Participants Referring to Only Size, Only Location, or to Size and Location Across Trials Information Type Age Group Size Only Location Only Size and Location 3-year-olds 3 (21%) 5 (36%) 5 (36%) 4-year-olds 9 (64%) 2 (14%) 3 (21%) 0 (0%) 4 (29%) 10 (71%) Note. There were 12 participants in each age group. One 3-year-old provided no references to either size or location information.

17 PREFERENCES FOR DISAMBIGUATING INFORMATION 443 location in adults, the individual patterns of performance indicate that most adults referred to size information at least once. Discussion When both location and size informations were available for disambiguating hiding places, 4-year-olds preferred to use size to location information. However, adults preferred to use location to size information. Three-year-olds showed no significant preference for either source of information. Moreover, children s use of location information to disambiguate hiding places was much lower than that of adults. Adults used location information on virtually all trials whereas children used location information on less than half the trials. These results suggest that young children s difficulty with using disambiguating location information stems from their difficulty with making more complex relational comparisons rather than difficulty with making any kind of relational comparison. We further addressed this hypothesis in a third experiment in which we pitted size information against color information. If young children s avoidance of location information stems from difficulty with more complex relations, then they should show no preference for color or size information. In other words, because neither size nor color information makes two binary comparisons, young children should show little or no preference for one source of information over the other. Likewise, adults should show no preference for color or size information. That is, unlike location information, neither size nor color information seems particularly well matched to the goal of finding a hidden object. EXPERIMENT 3 Method Participants Participants were 42 each of three-year-olds, four-year-olds, and adults from predominantly middle- to upper middle-class Caucasian families. The mean ages were 3 years and 9 months (range = 3;5 4;0), 4 years and 9 months (range = 4;1 5;0), and 19 years and 9 months (range = 18;4 22;11). There were 8 boys and 6 girls in the 3-year-old group, 7 boys and 7 girls in the 4-year-old group, and 7 men and 7 women in the adult group. The children and adults were recruited in the same manner as in the previous experiments. Apparatus and Materials The same dollhouse and furniture landmarks were used as in the previous experiments. The same eight pairs of small objects were used as in Experiment 2. In

18 444 PLUMERT, NICHOLS-WHITEHEAD this experiment, however, the two members of each small object pair differed both in size and in color. In addition, both members of each pair of small objects were placed next to the same piece of furniture. Thus, the hiding place could not be disambiguated using location information because both members of the pair were on the floor next to the same piece of furniture. Design and Procedure All aspects of the procedure were identical to those used in the previous experiments. After completing the communication task, participants were given the color and the size production tests used in the previous experiments. All children were able to name the four colors and distinguish between objects based on size. Coding and Measures Small object references, color references, and size references were coded in the same manner as in the previous experiments. Intercoder reliabilities were calculated on nine randomly selected participants (three from each age group). Exact percent agreement for small object references, color references, and size references were 100, 100, and 99%, respectively. Results References to the Small Object As in the previous experiments, children and adults alike usually referred to the small object when describing how to find the mouse. On average, 3-year-olds, 4-year-olds, and adults referred to the small object on 99% (SD = 3%), 99% (SD = 3%), and 99% (SD = 3%) of trials, respectively. A one-way ANOVA revealed that the percentage of small object references did not differ by age, F (2, 39) = 0.0, ns. References to Disambiguating Color and Size Information Were there developmental differences in preferences for using color and size information to disambiguate the hiding place? We first examined the percentage of trials on which participants provided any kind of disambiguating information as a measure of their overall success in the task. Prior to prompting, 3-year-olds, 4-year-olds, and adults provided some form of disambiguating information on 67% (SD = 26%), 64% (SD = 17%), and 99% (SD = 3%) of trials, respectively. After prompting, however, 3-year-olds, 4-year-olds, and adults provided some form of disambiguating information on 87% (SD = 16%), 92% (SD = 12%), and 99% (SD =.5%) of trials, respectively. A one-way ANOVA on references to disambiguating information after prompting with age as a factor was significant, F (2, 39) =

19 PREFERENCES FOR DISAMBIGUATING INFORMATION , p <.05. Tukey s HSD tests revealed that adults provided disambiguating information on a significantly greater percentage of trials than did the 3-year-olds. The 4-year-olds and adults did not differ significantly, nor did the 3- and 4-year-olds. To examine whether there were developmental differences in preferences for the two types of disambiguating information, we entered the percentage of color references and size references into an Age (3) x Information Type (2) repeated measures ANOVA. This analysis yielded significant effects of age, F (2, 39) = 24.10, p <.0001, and information type, F (1, 39) = 5.58, p <.05. Unlike the previous two experiments, this overall analysis did not yield a significant Age x Information Type interaction, F (2, 39) =.59, ns. However, because our goal was to examine whether there are age differences in preferences for using color and size information to disambiguate hiding places, we carried out a series of planned comparisons parallel to the analyses used in the previous experiments to examine Age x Information Type interactions. First, we examined whether there was a preference for either type of disambiguating information at each age. As shown in Figure 4, simple effects tests revealed a significant preference for size over color information for adults, F (1, 13) = 10.04, p <.01, but no significant preference for either type of information for 3-year-olds, F (1, 13) = 1.89, ns, or for 4-year-olds, F (1, 13) =.21, ns. Thus, when both color and size, but no location information was available for disambiguating the hiding place, adults exhibited a clear preference for size information. In contrast, 3- and 4-year-olds exhib- FIGURE 4 References to disambiguating size and color information by age.

20 446 PLUMERT, NICHOLS-WHITEHEAD ited no significant preference for either type of information. Second, we examined whether there were age differences in the percentage of references to each type of information. As shown in Figure 4, there was a significant effect of age for references to disambiguating size information, F (2, 39) = 7.03, p <.01, but no significant effect of age for references to disambiguating color information, F (2, 39) = 2.06, ns. Follow-up analyses revealed that adults referred to size information on a much higher percentage of trials than did 3- and 4-year-olds. Three- and 4-year-olds did not differ significantly. Use of redundant disambiguating information. We also examined whether there were age differences in the propensity to provide redundant disambiguating information (i.e., both size and color information). To address this issue, the percentage of trials in which participants referred to both color and size information (e.g., under the big pot with the red lid ) was entered into a one-way ANOVA with age as a between-subjects factor. This analysis yielded a significant effect of age, F (2, 39) = 24.10, p < Follow-up analyses revealed that adults provided redundant information on a significantly greater percentage of trials than did 3- and 4-year-olds. Three-year-olds, 4-year-olds, and adults provided redundant color and size information on 3% (SD = 7%), 3% (SD = 10%), and 49% (SD = 33%), of trials, respectively. Individual patterns of performance. Finally, we examined individual patterns of performance to determine whether participants in each age group showed strong biases toward color or size information. Across the eight test trials, we calculated the percentage of participants who referred only to color or only to size information, or referred at least once to each type of information (but not necessarily in the same trial). As shown in Table 3, most participants in the three age groups referred at least once to each type of information across the eight trials. A few 3- and 4-year-olds showed a bias toward size information (they never referred to color information on any trial). Thus, although the group data show a strong bias toward TABLE 3 Number of Participants Referring to Only Color, Only Size, or to Color and Size Across Trials Information Type Age Group Color Only Size Only Color and Size 3-year-olds 1 (7%) 3 (21%) 10 (71%) 4-year-olds 1 (7%) 4 (29%) 9 (64%) Adults 0 (0%) 1 (7%) 13 (93%) Note. There were 12 participants in each age group.