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Solving spatial tasks with unaligned layouts: The difficulty of dealing with conflicting information
J. Experimental Child Psychology 83 (2002) 291–303 www.academicpress.com
Solving spatial tasks with unaligned layouts: The difficulty of dealing with conflicting information Marina Vasilyeva* Department of Pschycology, University of Chicago, 5848 S. University Avenue, Chicago, IL 60637, USA Received 20 August 2001; revised 7 October 2002
Abstract Previous research has shown that preschool children have difficulty using relational information in spatial tasks. The present study investigates whether this difficulty is due, in part, to childrenÕs inability to deal with situations of conflict where both objective and egocentric cues are available and point to different responses. Two studies were conducted to compare performance in the presence versus absence of conflicting cues. In Study 1, 40 four-year-olds had to locate an object in a single layout presented from different perspectives. In Study 2, 39 four-year-olds had to transfer locational information between two unaligned layouts. The presence of conflict significantly affected childrenÕs performance in both studies. The results are discussed in the context of similar findings in other cognitive domains. Ó 2002 Elsevier Science (USA). All rights reserved. Keywords: Spatial relations; Unaligned layouts; Egocentric coding; Conflicting cues
The ability to locate objects in space is essential for the successful functioning of mobile creatures. People rely on this ability in various everyday situations, for example, when they have to find a car in a large parking lot or remember the best route through a familiar neighborhood. Previous *
Fax: 1-773-834-5261. E-mail address: [email protected].
0022-0965/02/$ - see front matter Ó 2002 Elsevier Science (USA). All rights reserved. PII: S 0 0 2 2 - 0 9 6 5 ( 0 2 ) 0 0 1 5 1 - 0
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research has shown that preschool children perform poorly on many tasks that require locating objects in spatial layouts (Piaget & Inhelder, 1967; see also Herman & Siegel, 1978; Laurendeau & Pinard, 1970; Liben & Downs, 1989). Notably, children have difficulty finding the correct location when their orientation relative to the layout has changed. Piaget has argued that childrenÕs difficulties result from their reliance on egocentric information (i.e., coding location relative to self) rather than objective information (i.e., coding location relative to external features of the environment). The evidence of spatial egocentrism comes from perspectivetaking studies (e.g., Piaget & Inhelder, 1967) as well as from research on unaligned maps and models (e.g., Liben & Downs, 1989). However, there is also accumulating evidence of successful performance by preschoolers on tasks involving change in spatial orientation (for review, see Newcombe, 1989). Thus, existing work has yielded inconsistent results; based on available data, one cannot definitively conclude that preschool children lack the ability to code location independently of their own position in space. The present research investigates a potential reason for the inconsistencies in previous findings. The studies reported here examine whether children have difficulty with specific spatial tasks in which objective cues come into conflict with egocentric cues. In such situations of conflict, children may fail to use objective relational information and instead resort to an egocentric strategy. In contrast, in the situations where conflicting egocentric cues are removed, children may demonstrate the use of objective spatial information. Consider the kinds of tasks where children have been shown to rely on egocentric cues. The initial evidence of spatial egocentrism comes from perspective-taking studies: when asked to indicate how a layout would look from different viewpoints, children select the layout shown from their own perspective (Piaget & Inhelder, 1967; see also Flavell, 1968; Laurendeau & Pinard, 1970). Further evidence of difficulties with the use of objective information comes from research on unaligned maps and models (Blades & Spencer, 1994; Bluestein & Acredolo, 1979; Liben & Downs, 1989). In these studies, children are presented with two spatial layouts, one representing the other. They are shown a target location in the first space and asked to find the corresponding location in the second space. When the layouts are not aligned and the task can only be solved using objective spatial cues, preschool children have difficulty finding the correct location. A common feature of spatial tasks described above is that they require children to deal with conflicting information. By changing the orientation of a single layout or by presenting two unaligned layouts, researchers create a situation where egocentric spatial cues lead to a different response than objective spatial cues. In the present research the availability of egocentric information is manipulated, which makes it possible to compare directly
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Fig. 1. Spatial layout in different orientations. (A) Original orientation, (B) rotated 180°, (C) rotated 90°. Circle represents a unique landmark in the layout and squares represent identical objects.
childrenÕs performance in the presence versus in the absence of conflicting cues. In the two studies presented below, children were shown spatial layouts where the locations of objects could be coded both objectively and egocentrically. For example, one layout contained two identical objects and a unique landmark (Fig. 1). The location of a target in Fig. 1A could be coded as being close to the landmark (objective cue) or as being on the left side of the layout (egocentric cue). Children had to find the target following a change in the layout orientation. In one condition (Fig. 1B), the layout was rotated so that both objective and egocentric cues were available but led to different responses (i.e., location closest to the landmark vs. location on the left side of the layout). In the other condition (Fig. 1C), the layout was rotated so that children could still use objective cues but they could not rely on previously encoded egocentric information because the target and the foil did not differ with respect to ‘‘right-left’’ positioning. If children show poor performance in both conditions involving unaligned layouts, it would support the view that they cannot code locations objectively. If, however, their performance improves with the removal of egocentric cues, it would provide support for an alternative view of early spatial competence. Such findings would suggest that children are capable of using objective spatial information, but only when conflicting egocentric information is not available.
Study 1 Study 1 explored whether the presence of conflicting cues affected childrenÕs ability to locate objects in a single spatial layout shown from different perspectives. To manipulate the availability of conflicting cues, the layout orientation was changed by either 180° (as in Fig. 1B) or by 90° (as in Fig. 1C). As discussed above, the first type of rotation created a conflict
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between egocentric and objective cues while the second type of rotation eliminated the conflict. Thus, changing the orientation by 180° was hypothesized to make the task more difficult than changing the orientation by 90°. Note that the orientation of the layout relative to the child can be changed by rotating the layout (‘‘layout moves’’ condition) or by moving the child around it (‘‘child moves’’ condition). Existing studies suggest that performance may vary depending on how the change of spatial orientation is carried out (e.g., Huttenlocher & Presson, 1979). There is evidence that scene recognition is harder in a ‘‘layout moves’’ condition than in a ‘‘child moves’’ condition (Simons & Wang, 1998). In the present study children were tested in both conditions to explore whether the presence of conflicting information had a differential effect on performance depending on the difficulty of the task. In addition, the present studies examined whether childrenÕs performance with unaligned layouts depended on the kind of objective information that was available to them. Most existing studies examined the ability to locate an object based on its relation to a single-standing landmark. Recent evidence shows that children are also sensitive to other types of spatial relations, such as the relation of an object to geometric features of space (Hermer & Spelke, 1996). The layouts used in the present research involved different types of spatial relations. One layout (Fig. 2A) included two identical objects that differed in terms of distance to a single landmark. Another layout (Fig. 2B) included two identical objects that differed in their positions with respect to the framework: one object was placed near the border of the layout and the other was placed near the center. The third layout (Fig. 2C) contained two identical objects placed in the middle of the adjacent walls of the rectangular frame. The positions of objects could be differentiated based on relative lengths of the sides of the layout; this kind of geometric information has been successfully used by children in other spatial tasks (Hermer & Spelke, 1996; Learmonth, Newcombe, & Huttenlocher, 2001).
Fig. 2. Three types of spatial layouts. (A) Relation to the landmark, (B) relation to the boarder, (C) relation to the side length. Circle represents a unique landmark in the layout and squares represent identical objects.
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Participants Twenty children participated in the ‘‘child moves’’ condition (9 girls and 11 boys) and the other 20 children participated in the ‘‘layout moves’’ condition (9 girls and 11 boys). Children ranged in age from 48 to 59 months, with a mean age of 53 months. All participants were recruited through preschools in Chicago and its suburbs. They were predominantly from middleclass families. Materials Three layouts were constructed out of plywood and covered with felt fabric. The layouts shown in Figs. 2A and 2B were 2 ft. 2 ft. in size; the layout shown in Fig. 2C was 1.5 ft. 4 ft. in size. Two red blocks (2.5 in. 2.5 in. 1.5 in.) served as identical objects for all three layouts and a yellow cylinder (3 in. high, 1.5 in. diameter) served as a unique object for the first layout. Non-transparent cloth was used to cover the layouts. Twelve small plastic toys were used in a game-like procedure. Procedure The experimenter and the child stood in front of a layout that was placed on a rotating stool. The experimenter told the child that the layout was a magic playground where little toy people liked to play and that each toy character had a favorite rock on this playground. A practice trial was administered to ensure that the child understood the need to discriminate between different ‘‘rocks.’’ The experimenter put a Barney toy on one of the blocks and told the child that this was BarneyÕs favorite rock. Then the experimenter removed Barney from the playground and asked the child to put him back on his favorite rock. If the child made a mistake, he/she was corrected. The practice was followed by 12 experimental trials in which the experimenter put a toy on one of the blocks, then handed the toy to the child, and covered the layout. In the ‘‘child moves’’ condition the experimenter said, ‘‘LetÕs take Elmo (or some other character) for a walk,’’ walked with the child around the room for about 20 s and then approached the layout. In the ‘‘layout moves’’ condition the experimenter said, ‘‘LetÕs spin the magic playground’’ and rotated the layout for about 20 s. In both conditions, half the trials ended with the layout rotated 90° and half the trials ended with the layout rotated 180° relative to the childÕs original point of view. At the end of each trial, the cover was removed from the layout and the child was asked to put the toy on its favorite rock. The two experimental conditions (‘‘child moves’’ and ‘‘layout moves’’) were tested as a between-subject factor. Within these conditions, each child
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was presented with three different layouts. After completion of four trials with a given layout, the child was given a short break (about 1 min) during which the layout was replaced with a new one. The order of presentation of layouts was randomized across children. Results An analysis of variance was carried out to examine whether, as hypothesized above, the accuracy of childrenÕs performance was affected by the amount of layout rotation (which would indicate the effect of conflicting information). The analysis also explored whether a potential effect of conflicting information varied depending on the type of the layout and on the way in which layout orientation was changed (i.e., ‘‘child moves’’ or ‘‘layout moves’’). For this analysis, an accuracy score was calculated for each child as a proportion of correct responses. An ANOVA was conducted on the accuracy scores with four independent variables: gender, type of spatial layout, manner of change (‘‘child moves’’ vs. ‘‘layout moves’’), and amount of rotation (90° vs. 180°). The analysis showed that gender did not affect accuracy, F ð1; 36Þ ¼ :08, p ¼ :79, and did not produce any significant interactions (in all interactions p > :05). Also, neither the type of spatial layout, F ð2; 72Þ ¼ :76, p ¼ :47, nor its interactions were significant (in all interactions p > :05). The two factors that affected childrenÕs performance were the manner of change, F ð1; 36Þ ¼ 4:48, p < :05, and the amount of rotation, F ð1; 36Þ ¼ 6:28, p < :05; there was also a significant interaction between these factors, F ð1; 36Þ ¼ 4:67, p < :05 (see Fig. 3). Simple effect contrasts showed that in the ‘‘child moves’’ condition, the difference between the 90° rotation and
Fig. 3. Performance in Studies 1 and 2 with 90° rotated layouts versus 180° rotated layouts. *, denotes significant difference between group means, p < :05.
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the 180° rotation was not significant: TukeyÕs q2;38 ¼ :29, p > :05. In the ‘‘layout moves’’ condition, the difference between the 90° rotation and the 180° rotation was significant: TukeyÕs q2;38 ¼ 4:62, p < :05. When the layout was rotated 90°, the performance level was high, but when the layout was rotated 180°, childrenÕs performance was significantly less accurate. Following the analysis of variance, childrenÕs accuracy scores were compared to chance level (.5); t tests with Bonferroni corrections showed that the average group performance was above chance in all experimental conditions (p < :001). The examination of individual performance showed that 2 out of 40 participants had overall accuracy scores that did not exceed chance level. Both children participated in the ‘‘layout moves’’ condition and made most of their errors (75%) when the layout was rotated 180°. Discussion The fact that the accuracy of responses was above chance indicates that children were able to code locations non-egocentrically. They showed similar levels of performance with the three types of spatial layouts presented to them. At the same time, the performance varied across other experimental conditions. It was hypothesized that changing the orientation of the layout by 180° would make the task more difficult than changing the orientation by 90°. The predicted pattern of results was observed in the ‘‘layout moves’’ condition but not in the ‘‘child moves’’ condition. The ‘‘child moves’’ condition turned out to be an easy task, possibly because in dealing with a stationary layout, children relied on objective spatial cues both within and outside of that layout. Prior work has shown that children use information from surrounding space to locate objects in a layout placed within that space (e.g., Herman & Siegel, 1978). Thus, even though egocentric cues in the ‘‘child moves’’ condition pointed to the wrong response, objective cues both within and outside the layout pointed to the correct response and so children had no difficulty overcoming conflicting information. However, in the ‘‘layout moves’’ condition children could not rely on the objectÕs relations with the outside landmarks (since the layout position relative to outside landmarks has changed). In this condition the presence of conflicting cues affected childrenÕs performance. Study 1 provided evidence that, in dealing with a single spatial layout, fouryear-olds can use objective information but they are less likely to do so in the presence of conflicting cues. However, it may be argued that locating an object in a single layout is a very easy task for children of this age and demonstrating their successful performance on this task is not sufficient to argue that preschoolers have a general ability to use objective spatial cues. A stronger test of childrenÕs ability to code spatial relations objectively would be a transfer task involving unaligned layouts. Transferring locational information
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between spaces is a challenging problem for preschoolers; it requires extracting spatial cues from one space and applying them in another space. This task has been used in previous research to show that four-year-olds fail to code spatial relations objectively (Blades & Spencer, 1994; Bluestein & Acredolo, 1979; Liben & Downs, 1989). Study 2 explored whether poor performance observed in previous transfer studies could be due to the presence of conflicting information and whether the removal of conflict would allow children to demonstrate the use of objective cues.
Study 2 As discussed above, existing data show that the accuracy of transfer between unaligned spaces does not exceed chance in four-year-old children (e.g., Blades & Spencer, 1994). However, these data were obtained under conditions where objective spatial cues were pitted against egocentric cues. The present study included two experimental conditions. In the first condition, similar to previous studies, both objective and egocentric cues were available and led to opposite responses, while in the second condition egocentric cues were removed. Both conditions involved transfer between unaligned layouts so that accurate performance required the use of non-egocentric information. It was hypothesized that in the first condition children would perform poorly as they did in previous studies, but in the second condition, their performance would significantly improve, indicating the use of objective relational information. Participants There were 39 participants in this study; 20 children took part in the condition where the layouts were rotated by 90° and 19 children took part in the condition where the layouts were rotated by 180°. The children ranged in age from 48 to 59 months, with a mean age of 54 months. The recruitment procedure was the same as in Study 1. Materials Three pairs of spatial layouts were used; they were created by duplicating each of the three layouts from Study 1. Other materials were the same as in Study 1. Procedure Two identical layouts were placed in front of the child in the same orientation. The experimenter drew the childÕs attention to one of the layouts and
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described it as in the previous study. Then the experimenter introduced the second layout by saying, ‘‘Look at the other playground. See, it looks just like this one (pointing to the first layout). It has the same kind of rocks and they stand in the same way.’’ A practice trial was offered to introduce the procedure. The experimenter put a toy on a block in one of the layouts and told the child that this was the toyÕs favorite rock. Then the experimenter removed the toy from the layout and handed it to the child. The child was asked to find the rock on another playground that stood in the same way as the toyÕs favorite rock in the first space. If the child made an error, he/she was corrected. After the practice trial, the experimenter moved one layout about 2 yards away from the other one and rotated it according to one of the conditions (180° or 90°). On each experimental trial the experimenter placed a toy on one of identical blocks. The child then was given the toy and asked to take it to another playground and put it on its ‘‘favorite rock.’’ The experimenter walked with the child to the second layout to make sure that the child approached it from a predetermined direction. Different routes were used in moving from one layout to another to exclude the possibility that after the first couple of trials the child used route memory to identify the correct location. Children were randomly assigned to one of the two rotation conditions. Within these conditions each child was presented with three pairs of layouts displaying different types of spatial relations. The child had 4 trials with every type of layout, for a total of 12 trials. The trials were grouped by the type of the layout. The order of presentation of layouts was randomized across children. Results An analysis of variance was carried out to investigate whether the accuracy of childrenÕs performance was affected by the amount of layout rotation and whether this potential effect depended on the type of layout used. Accuracy scores were calculated as a proportion of correct responses. An ANOVA was carried out on the accuracy scores with three independent variables: gender, type of spatial layout, and amount of rotation. Similar to findings of Study 1, neither gender nor the type of spatial layout affected the accuracy of responses (for gender, F ð1; 35Þ ¼ 2:54, p ¼ :12; for the type of layout, F ð2; 70Þ ¼ :07, p ¼ :94; for all interactions, p > :05). Again, the amount of rotation had a significant effect on childrenÕs performance, F ð1; 35Þ ¼ 6:40, p < :05 (see Fig. 3). To evaluate the level of childrenÕs performance, their accuracy scores were compared to chance; t tests with Bonferroni corrections showed that in the 90° rotation children performed above chance with all spatial layouts (in all tests, p < :005). In the 180° rotation condition, children showed
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chance performance with all spatial layouts (for all tests, p > :05). To examine further the nature of the difference between the two conditions, the error patterns were analyzed. Since every child had 4 trials with each spatial layout, the accuracy score with a given layout could be 0, .25, .5, .75, or 1. In the 90° condition, the majority of imperfect scores (i.e., scores below 1) were at or above chance, that is .5 or .75. This performance points to the random nature of occasional errors made by children. In the 180° condition, the majority of imperfect scores were below chance, that is 0 or .25. This performance points to systematic use of an alternative strategy—relying on egocentric cues. Discussion As in Study 1, childrenÕs performance on a transfer task did not differ across the three spatial layouts presented to them. The factor that did affect the performance was the presence of conflicting information. In the situation pitting objective and egocentric cues against one another, the accuracy of four-year-old children was brought down to chance level. However, in the situation where egocentric cues were not available, most children performed successfully. The first of these two findings parallels the results of the previous research showing that in the presence of conflicting information fouryear-old children fail to use objective cues. The second finding provides new evidence about spatial skills of preschool children. It shows that in the absence of conflicting cues, the children can transfer objective relational information between unaligned spaces—the task viewed as one of the most difficult spatial problems for preschoolers.
General discussion The failure of preschool children to solve spatial tasks involving unaligned layouts was traditionally interpreted as evidence of their inability to use objective spatial cues. However, the present research clearly shows that four-year-olds can use objective cues to reproduce location in a single rotated layout (Study 1) as well as to transfer information between two unaligned layouts (Study 2). In both studies, children were able to utilize different kinds of objective spatial relations, including landmark and geometric information. In fact, childrenÕs performance with the layouts that involved landmark information was statistically equivalent to their performance with the layouts that involved geometric information. While the results indicate that four-year-old children are able to use different kinds of objective cues in dealing with rotated and unaligned layouts, the data also show that this ability is significantly impaired by the presence of conflicting egocentric information. The findings suggest that preschool
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children may code locations of objects in a spatial layout in terms of both objective and egocentric cues. If they are subsequently presented with a layout in which egocentric and objective cues are available and conflict with each other, children have to decide what type of information should be used. In this situation four-year-olds seem to assign a greater weight to egocentric cues, which leads them to erroneous responses. If, instead, children are presented with a layout in which egocentric cues cannot be applied, they rely on the encoded objective information and thus arrive at the correct response. The present research adds to a growing body of evidence indicating that the use of objective spatial strategies initially emerges in limited contexts. Previous work has shown that childrenÕs performance on tasks involving rotated layouts depends on a variety of factors, including salience and number of landmarks, response mode, naturalism of the task, and so forth (Acredolo, 1981; Gullo & Bersani, 1983; Hughes & Donaldson, 1979). Further, there is evidence that childrenÕs performance on tasks involving imagined layout rotation depends on the way perspective questions are asked (Huttenlocher & Presson, 1979; Newcombe, 1997). In particular, when the question sets up a conflict between a physically present frame of reference and an imagined frame of reference, children perform poorly, but when this conflict is eliminated, same-aged children perform successfully. The effect of conflicting information on childrenÕs performance in spatial domain may reflect a phenomenon common to other cognitive domains. For example, there is evidence that early ability to make probability judgments is affected by the presence of conflicting cues. Piaget (1965) argued that young children determine the probability of drawing a particular item based on the absolute (as opposed to relative) quantity of these items in a set. More recent work (Acredolo, OÕConnor, Banks, & Horobin, 1989) showed that five-year-olds can use relative quantity to make successful probability judgments. However, when the information about absolute quantity conflicts with the information about relative quantity, children resort to the use of absolute information, which leads them to wrong responses. Whereas it is possible to eliminate conflicting cues and thus enhance the level of performance in the experimental setting, in real life people are constantly confronted with situations in which they have to weigh conflicting cues against one another. It is possible that children develop a strategy for dealing with conflicting information in a particular domain through the accumulation of experience in that domain. For example, if children rely on egocentric cues when their orientation relative to a space has changed, they will not be able to find important places and objects, and this negative feedback will highlight the importance of objective spatial cues. It is also possible that children develop a general strategy for dealing with conflict that can be applied across domains. Around five years of age children begin to solve a variety of tasks by choosing appropriate cues in the presence of conflicting evidence. Younger children have difficulty coordinating
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different pieces of information and considering alternative interpretations of a particular situation. For example, Rock and colleagues have shown that 3and 4-year-olds find it difficult to achieve different perceptions of an ambiguous figure, even when they are informed about the ambiguity of the figure (Rock, Gopnick, & Hall, 1994). Jacques and Zelazo (2001) have shown that 4-year-olds perform poorly on the task that requires sorting cards according to different dimensions whereas 5-year-olds perform well on the same task. This evidence suggests that between 4 and 5 years of age children achieve a level of cognitive flexibility that allows them to think about a situation in more than one way. The ability to solve spatial tasks involving conflicting cues may depend on the development of cognitive flexibility because these tasks require that children recognize and coordinate different spatial strategies—i.e., egocentric and objective coding of location.
References Acredolo, L. (1981). Small- and large-scale spatial concepts in infancy and childhood. In L. Liben, A. Patterson, & N. Newcombe (Eds.), Spatial representation and behavior across the life span (pp. 63–81). New York: Academic Press. Acredolo, C., OÕConnor, J., Banks, L., & Horobin, K. (1989). ChildrenÕs ability to make probability estimates: Skills revealed through application of AndersonÕs functional measurement methodology. Child Development, 60, 933–945. Blades, M., & Spencer, C. (1994). The development of childrenÕs ability to use spatial representations. In H. W. Reese (Ed.), Advances in child development and behavior (Vol. 25, pp. 157–199). New York: Academic Press. Bluestein, M., & Acredolo, L. (1979). Developmental changes in map reading skill. Child Development, 50, 691–697. Flavell, J. H. (1968). The development of role-taking and communication skills in children. New York: Wiley. Gullo, D. F., & Bersani, C. (1983). Effects of three experimental conditions on preschool childrenÕs ability to coordinate visual perspectives. Perceptual and Motor Skills, 56, 675–678. Herman, J. F., & Siegel, A. W. (1978). The development of cognitive mapping of the large-scale environment. Journal of Experimental Child Psychology, 26, 389–406. Hermer, L., & Spelke, E. (1996). Modularity and development: The case of spatial reorientation. Cognition, 61, 195–232. Hughes, M., & Donaldson, M. (1979). The use of hiding games for studying the coordination of viewpoints. Educational Review, 31, 133–140. Huttenlocher, J., & Presson, C. C. (1979). The coding and transformation of spatial information. Cognitive Psychology, 11, 375–394. Jacques, S., & Zelazo, P. D. (2001). The flexible item selection task (FIST): A measure of executive function in preschoolers. Developmental Neuropsychology, 20, 573–591. Laurendeau, M., & Pinard, A. (1970). The development of the concept of space in the child. New York: International Universities Press. Learmonth, A., Newcombe, N., & Huttenlocher, J. (2001). ToddlersÕ use of metric information and landmarks to reorient. Journal of Experimental Child Psychology, 80, 225–244. Liben, L. S., & Downs, R. M. (1989). Understanding maps as symbols: The development of map concepts in children. In H. W. Reese (Ed.), Advances in child development and behavior (Vol. 22, pp. 145–201). New York: Academic Press.
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Newcombe, N. (1989). Development of spatial perspective taking. In H. W. Reese (Ed.), Advances in child development and behavior (Vol. 22, pp. 203–247). New York: Academic Press. Newcombe, N. (1997). New perspectives on spatial representation: What different tasks tell us about how people remember location. In N. Foreman & R. Gillet (Eds.). Spatial cognition in the child and adult: Vol. 1. The handbook of spatial research paradigms and methodologies (pp. 85–102). Psychology Press: Hove, England. Piaget, J. (1965). The childÕs conception of number. New York: Norton. Piaget, J., & Inhelder, B. (1967). The childÕs conception of space. London: Routledge & Kegan Paul. Rock, I., Gopnick, A., & Hall, S. (1994). Do young children reverse ambiguous figures? Perception, 23, 635–644. Simons, D. J., & Wang, R. F. (1998). Perceiving real-world viewpoint changes. Psychological Science, 9, 315–320.
Solving spatial tasks with unaligned layouts: The difficulty of dealing with conflicting information Marina Vasilyeva* Department of Pschycology, University of Chicago, 5848 S. University Avenue, Chicago, IL 60637, USA Received 20 August 2001; revised 7 October 2002
Abstract Previous research has shown that preschool children have difficulty using relational information in spatial tasks. The present study investigates whether this difficulty is due, in part, to childrenÕs inability to deal with situations of conflict where both objective and egocentric cues are available and point to different responses. Two studies were conducted to compare performance in the presence versus absence of conflicting cues. In Study 1, 40 four-year-olds had to locate an object in a single layout presented from different perspectives. In Study 2, 39 four-year-olds had to transfer locational information between two unaligned layouts. The presence of conflict significantly affected childrenÕs performance in both studies. The results are discussed in the context of similar findings in other cognitive domains. Ó 2002 Elsevier Science (USA). All rights reserved. Keywords: Spatial relations; Unaligned layouts; Egocentric coding; Conflicting cues
The ability to locate objects in space is essential for the successful functioning of mobile creatures. People rely on this ability in various everyday situations, for example, when they have to find a car in a large parking lot or remember the best route through a familiar neighborhood. Previous *
Fax: 1-773-834-5261. E-mail address: [email protected].
0022-0965/02/$ - see front matter Ó 2002 Elsevier Science (USA). All rights reserved. PII: S 0 0 2 2 - 0 9 6 5 ( 0 2 ) 0 0 1 5 1 - 0
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research has shown that preschool children perform poorly on many tasks that require locating objects in spatial layouts (Piaget & Inhelder, 1967; see also Herman & Siegel, 1978; Laurendeau & Pinard, 1970; Liben & Downs, 1989). Notably, children have difficulty finding the correct location when their orientation relative to the layout has changed. Piaget has argued that childrenÕs difficulties result from their reliance on egocentric information (i.e., coding location relative to self) rather than objective information (i.e., coding location relative to external features of the environment). The evidence of spatial egocentrism comes from perspectivetaking studies (e.g., Piaget & Inhelder, 1967) as well as from research on unaligned maps and models (e.g., Liben & Downs, 1989). However, there is also accumulating evidence of successful performance by preschoolers on tasks involving change in spatial orientation (for review, see Newcombe, 1989). Thus, existing work has yielded inconsistent results; based on available data, one cannot definitively conclude that preschool children lack the ability to code location independently of their own position in space. The present research investigates a potential reason for the inconsistencies in previous findings. The studies reported here examine whether children have difficulty with specific spatial tasks in which objective cues come into conflict with egocentric cues. In such situations of conflict, children may fail to use objective relational information and instead resort to an egocentric strategy. In contrast, in the situations where conflicting egocentric cues are removed, children may demonstrate the use of objective spatial information. Consider the kinds of tasks where children have been shown to rely on egocentric cues. The initial evidence of spatial egocentrism comes from perspective-taking studies: when asked to indicate how a layout would look from different viewpoints, children select the layout shown from their own perspective (Piaget & Inhelder, 1967; see also Flavell, 1968; Laurendeau & Pinard, 1970). Further evidence of difficulties with the use of objective information comes from research on unaligned maps and models (Blades & Spencer, 1994; Bluestein & Acredolo, 1979; Liben & Downs, 1989). In these studies, children are presented with two spatial layouts, one representing the other. They are shown a target location in the first space and asked to find the corresponding location in the second space. When the layouts are not aligned and the task can only be solved using objective spatial cues, preschool children have difficulty finding the correct location. A common feature of spatial tasks described above is that they require children to deal with conflicting information. By changing the orientation of a single layout or by presenting two unaligned layouts, researchers create a situation where egocentric spatial cues lead to a different response than objective spatial cues. In the present research the availability of egocentric information is manipulated, which makes it possible to compare directly
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Fig. 1. Spatial layout in different orientations. (A) Original orientation, (B) rotated 180°, (C) rotated 90°. Circle represents a unique landmark in the layout and squares represent identical objects.
childrenÕs performance in the presence versus in the absence of conflicting cues. In the two studies presented below, children were shown spatial layouts where the locations of objects could be coded both objectively and egocentrically. For example, one layout contained two identical objects and a unique landmark (Fig. 1). The location of a target in Fig. 1A could be coded as being close to the landmark (objective cue) or as being on the left side of the layout (egocentric cue). Children had to find the target following a change in the layout orientation. In one condition (Fig. 1B), the layout was rotated so that both objective and egocentric cues were available but led to different responses (i.e., location closest to the landmark vs. location on the left side of the layout). In the other condition (Fig. 1C), the layout was rotated so that children could still use objective cues but they could not rely on previously encoded egocentric information because the target and the foil did not differ with respect to ‘‘right-left’’ positioning. If children show poor performance in both conditions involving unaligned layouts, it would support the view that they cannot code locations objectively. If, however, their performance improves with the removal of egocentric cues, it would provide support for an alternative view of early spatial competence. Such findings would suggest that children are capable of using objective spatial information, but only when conflicting egocentric information is not available.
Study 1 Study 1 explored whether the presence of conflicting cues affected childrenÕs ability to locate objects in a single spatial layout shown from different perspectives. To manipulate the availability of conflicting cues, the layout orientation was changed by either 180° (as in Fig. 1B) or by 90° (as in Fig. 1C). As discussed above, the first type of rotation created a conflict
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between egocentric and objective cues while the second type of rotation eliminated the conflict. Thus, changing the orientation by 180° was hypothesized to make the task more difficult than changing the orientation by 90°. Note that the orientation of the layout relative to the child can be changed by rotating the layout (‘‘layout moves’’ condition) or by moving the child around it (‘‘child moves’’ condition). Existing studies suggest that performance may vary depending on how the change of spatial orientation is carried out (e.g., Huttenlocher & Presson, 1979). There is evidence that scene recognition is harder in a ‘‘layout moves’’ condition than in a ‘‘child moves’’ condition (Simons & Wang, 1998). In the present study children were tested in both conditions to explore whether the presence of conflicting information had a differential effect on performance depending on the difficulty of the task. In addition, the present studies examined whether childrenÕs performance with unaligned layouts depended on the kind of objective information that was available to them. Most existing studies examined the ability to locate an object based on its relation to a single-standing landmark. Recent evidence shows that children are also sensitive to other types of spatial relations, such as the relation of an object to geometric features of space (Hermer & Spelke, 1996). The layouts used in the present research involved different types of spatial relations. One layout (Fig. 2A) included two identical objects that differed in terms of distance to a single landmark. Another layout (Fig. 2B) included two identical objects that differed in their positions with respect to the framework: one object was placed near the border of the layout and the other was placed near the center. The third layout (Fig. 2C) contained two identical objects placed in the middle of the adjacent walls of the rectangular frame. The positions of objects could be differentiated based on relative lengths of the sides of the layout; this kind of geometric information has been successfully used by children in other spatial tasks (Hermer & Spelke, 1996; Learmonth, Newcombe, & Huttenlocher, 2001).
Fig. 2. Three types of spatial layouts. (A) Relation to the landmark, (B) relation to the boarder, (C) relation to the side length. Circle represents a unique landmark in the layout and squares represent identical objects.
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Participants Twenty children participated in the ‘‘child moves’’ condition (9 girls and 11 boys) and the other 20 children participated in the ‘‘layout moves’’ condition (9 girls and 11 boys). Children ranged in age from 48 to 59 months, with a mean age of 53 months. All participants were recruited through preschools in Chicago and its suburbs. They were predominantly from middleclass families. Materials Three layouts were constructed out of plywood and covered with felt fabric. The layouts shown in Figs. 2A and 2B were 2 ft. 2 ft. in size; the layout shown in Fig. 2C was 1.5 ft. 4 ft. in size. Two red blocks (2.5 in. 2.5 in. 1.5 in.) served as identical objects for all three layouts and a yellow cylinder (3 in. high, 1.5 in. diameter) served as a unique object for the first layout. Non-transparent cloth was used to cover the layouts. Twelve small plastic toys were used in a game-like procedure. Procedure The experimenter and the child stood in front of a layout that was placed on a rotating stool. The experimenter told the child that the layout was a magic playground where little toy people liked to play and that each toy character had a favorite rock on this playground. A practice trial was administered to ensure that the child understood the need to discriminate between different ‘‘rocks.’’ The experimenter put a Barney toy on one of the blocks and told the child that this was BarneyÕs favorite rock. Then the experimenter removed Barney from the playground and asked the child to put him back on his favorite rock. If the child made a mistake, he/she was corrected. The practice was followed by 12 experimental trials in which the experimenter put a toy on one of the blocks, then handed the toy to the child, and covered the layout. In the ‘‘child moves’’ condition the experimenter said, ‘‘LetÕs take Elmo (or some other character) for a walk,’’ walked with the child around the room for about 20 s and then approached the layout. In the ‘‘layout moves’’ condition the experimenter said, ‘‘LetÕs spin the magic playground’’ and rotated the layout for about 20 s. In both conditions, half the trials ended with the layout rotated 90° and half the trials ended with the layout rotated 180° relative to the childÕs original point of view. At the end of each trial, the cover was removed from the layout and the child was asked to put the toy on its favorite rock. The two experimental conditions (‘‘child moves’’ and ‘‘layout moves’’) were tested as a between-subject factor. Within these conditions, each child
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was presented with three different layouts. After completion of four trials with a given layout, the child was given a short break (about 1 min) during which the layout was replaced with a new one. The order of presentation of layouts was randomized across children. Results An analysis of variance was carried out to examine whether, as hypothesized above, the accuracy of childrenÕs performance was affected by the amount of layout rotation (which would indicate the effect of conflicting information). The analysis also explored whether a potential effect of conflicting information varied depending on the type of the layout and on the way in which layout orientation was changed (i.e., ‘‘child moves’’ or ‘‘layout moves’’). For this analysis, an accuracy score was calculated for each child as a proportion of correct responses. An ANOVA was conducted on the accuracy scores with four independent variables: gender, type of spatial layout, manner of change (‘‘child moves’’ vs. ‘‘layout moves’’), and amount of rotation (90° vs. 180°). The analysis showed that gender did not affect accuracy, F ð1; 36Þ ¼ :08, p ¼ :79, and did not produce any significant interactions (in all interactions p > :05). Also, neither the type of spatial layout, F ð2; 72Þ ¼ :76, p ¼ :47, nor its interactions were significant (in all interactions p > :05). The two factors that affected childrenÕs performance were the manner of change, F ð1; 36Þ ¼ 4:48, p < :05, and the amount of rotation, F ð1; 36Þ ¼ 6:28, p < :05; there was also a significant interaction between these factors, F ð1; 36Þ ¼ 4:67, p < :05 (see Fig. 3). Simple effect contrasts showed that in the ‘‘child moves’’ condition, the difference between the 90° rotation and
Fig. 3. Performance in Studies 1 and 2 with 90° rotated layouts versus 180° rotated layouts. *, denotes significant difference between group means, p < :05.
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the 180° rotation was not significant: TukeyÕs q2;38 ¼ :29, p > :05. In the ‘‘layout moves’’ condition, the difference between the 90° rotation and the 180° rotation was significant: TukeyÕs q2;38 ¼ 4:62, p < :05. When the layout was rotated 90°, the performance level was high, but when the layout was rotated 180°, childrenÕs performance was significantly less accurate. Following the analysis of variance, childrenÕs accuracy scores were compared to chance level (.5); t tests with Bonferroni corrections showed that the average group performance was above chance in all experimental conditions (p < :001). The examination of individual performance showed that 2 out of 40 participants had overall accuracy scores that did not exceed chance level. Both children participated in the ‘‘layout moves’’ condition and made most of their errors (75%) when the layout was rotated 180°. Discussion The fact that the accuracy of responses was above chance indicates that children were able to code locations non-egocentrically. They showed similar levels of performance with the three types of spatial layouts presented to them. At the same time, the performance varied across other experimental conditions. It was hypothesized that changing the orientation of the layout by 180° would make the task more difficult than changing the orientation by 90°. The predicted pattern of results was observed in the ‘‘layout moves’’ condition but not in the ‘‘child moves’’ condition. The ‘‘child moves’’ condition turned out to be an easy task, possibly because in dealing with a stationary layout, children relied on objective spatial cues both within and outside of that layout. Prior work has shown that children use information from surrounding space to locate objects in a layout placed within that space (e.g., Herman & Siegel, 1978). Thus, even though egocentric cues in the ‘‘child moves’’ condition pointed to the wrong response, objective cues both within and outside the layout pointed to the correct response and so children had no difficulty overcoming conflicting information. However, in the ‘‘layout moves’’ condition children could not rely on the objectÕs relations with the outside landmarks (since the layout position relative to outside landmarks has changed). In this condition the presence of conflicting cues affected childrenÕs performance. Study 1 provided evidence that, in dealing with a single spatial layout, fouryear-olds can use objective information but they are less likely to do so in the presence of conflicting cues. However, it may be argued that locating an object in a single layout is a very easy task for children of this age and demonstrating their successful performance on this task is not sufficient to argue that preschoolers have a general ability to use objective spatial cues. A stronger test of childrenÕs ability to code spatial relations objectively would be a transfer task involving unaligned layouts. Transferring locational information
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between spaces is a challenging problem for preschoolers; it requires extracting spatial cues from one space and applying them in another space. This task has been used in previous research to show that four-year-olds fail to code spatial relations objectively (Blades & Spencer, 1994; Bluestein & Acredolo, 1979; Liben & Downs, 1989). Study 2 explored whether poor performance observed in previous transfer studies could be due to the presence of conflicting information and whether the removal of conflict would allow children to demonstrate the use of objective cues.
Study 2 As discussed above, existing data show that the accuracy of transfer between unaligned spaces does not exceed chance in four-year-old children (e.g., Blades & Spencer, 1994). However, these data were obtained under conditions where objective spatial cues were pitted against egocentric cues. The present study included two experimental conditions. In the first condition, similar to previous studies, both objective and egocentric cues were available and led to opposite responses, while in the second condition egocentric cues were removed. Both conditions involved transfer between unaligned layouts so that accurate performance required the use of non-egocentric information. It was hypothesized that in the first condition children would perform poorly as they did in previous studies, but in the second condition, their performance would significantly improve, indicating the use of objective relational information. Participants There were 39 participants in this study; 20 children took part in the condition where the layouts were rotated by 90° and 19 children took part in the condition where the layouts were rotated by 180°. The children ranged in age from 48 to 59 months, with a mean age of 54 months. The recruitment procedure was the same as in Study 1. Materials Three pairs of spatial layouts were used; they were created by duplicating each of the three layouts from Study 1. Other materials were the same as in Study 1. Procedure Two identical layouts were placed in front of the child in the same orientation. The experimenter drew the childÕs attention to one of the layouts and
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described it as in the previous study. Then the experimenter introduced the second layout by saying, ‘‘Look at the other playground. See, it looks just like this one (pointing to the first layout). It has the same kind of rocks and they stand in the same way.’’ A practice trial was offered to introduce the procedure. The experimenter put a toy on a block in one of the layouts and told the child that this was the toyÕs favorite rock. Then the experimenter removed the toy from the layout and handed it to the child. The child was asked to find the rock on another playground that stood in the same way as the toyÕs favorite rock in the first space. If the child made an error, he/she was corrected. After the practice trial, the experimenter moved one layout about 2 yards away from the other one and rotated it according to one of the conditions (180° or 90°). On each experimental trial the experimenter placed a toy on one of identical blocks. The child then was given the toy and asked to take it to another playground and put it on its ‘‘favorite rock.’’ The experimenter walked with the child to the second layout to make sure that the child approached it from a predetermined direction. Different routes were used in moving from one layout to another to exclude the possibility that after the first couple of trials the child used route memory to identify the correct location. Children were randomly assigned to one of the two rotation conditions. Within these conditions each child was presented with three pairs of layouts displaying different types of spatial relations. The child had 4 trials with every type of layout, for a total of 12 trials. The trials were grouped by the type of the layout. The order of presentation of layouts was randomized across children. Results An analysis of variance was carried out to investigate whether the accuracy of childrenÕs performance was affected by the amount of layout rotation and whether this potential effect depended on the type of layout used. Accuracy scores were calculated as a proportion of correct responses. An ANOVA was carried out on the accuracy scores with three independent variables: gender, type of spatial layout, and amount of rotation. Similar to findings of Study 1, neither gender nor the type of spatial layout affected the accuracy of responses (for gender, F ð1; 35Þ ¼ 2:54, p ¼ :12; for the type of layout, F ð2; 70Þ ¼ :07, p ¼ :94; for all interactions, p > :05). Again, the amount of rotation had a significant effect on childrenÕs performance, F ð1; 35Þ ¼ 6:40, p < :05 (see Fig. 3). To evaluate the level of childrenÕs performance, their accuracy scores were compared to chance; t tests with Bonferroni corrections showed that in the 90° rotation children performed above chance with all spatial layouts (in all tests, p < :005). In the 180° rotation condition, children showed
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chance performance with all spatial layouts (for all tests, p > :05). To examine further the nature of the difference between the two conditions, the error patterns were analyzed. Since every child had 4 trials with each spatial layout, the accuracy score with a given layout could be 0, .25, .5, .75, or 1. In the 90° condition, the majority of imperfect scores (i.e., scores below 1) were at or above chance, that is .5 or .75. This performance points to the random nature of occasional errors made by children. In the 180° condition, the majority of imperfect scores were below chance, that is 0 or .25. This performance points to systematic use of an alternative strategy—relying on egocentric cues. Discussion As in Study 1, childrenÕs performance on a transfer task did not differ across the three spatial layouts presented to them. The factor that did affect the performance was the presence of conflicting information. In the situation pitting objective and egocentric cues against one another, the accuracy of four-year-old children was brought down to chance level. However, in the situation where egocentric cues were not available, most children performed successfully. The first of these two findings parallels the results of the previous research showing that in the presence of conflicting information fouryear-old children fail to use objective cues. The second finding provides new evidence about spatial skills of preschool children. It shows that in the absence of conflicting cues, the children can transfer objective relational information between unaligned spaces—the task viewed as one of the most difficult spatial problems for preschoolers.
General discussion The failure of preschool children to solve spatial tasks involving unaligned layouts was traditionally interpreted as evidence of their inability to use objective spatial cues. However, the present research clearly shows that four-year-olds can use objective cues to reproduce location in a single rotated layout (Study 1) as well as to transfer information between two unaligned layouts (Study 2). In both studies, children were able to utilize different kinds of objective spatial relations, including landmark and geometric information. In fact, childrenÕs performance with the layouts that involved landmark information was statistically equivalent to their performance with the layouts that involved geometric information. While the results indicate that four-year-old children are able to use different kinds of objective cues in dealing with rotated and unaligned layouts, the data also show that this ability is significantly impaired by the presence of conflicting egocentric information. The findings suggest that preschool
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children may code locations of objects in a spatial layout in terms of both objective and egocentric cues. If they are subsequently presented with a layout in which egocentric and objective cues are available and conflict with each other, children have to decide what type of information should be used. In this situation four-year-olds seem to assign a greater weight to egocentric cues, which leads them to erroneous responses. If, instead, children are presented with a layout in which egocentric cues cannot be applied, they rely on the encoded objective information and thus arrive at the correct response. The present research adds to a growing body of evidence indicating that the use of objective spatial strategies initially emerges in limited contexts. Previous work has shown that childrenÕs performance on tasks involving rotated layouts depends on a variety of factors, including salience and number of landmarks, response mode, naturalism of the task, and so forth (Acredolo, 1981; Gullo & Bersani, 1983; Hughes & Donaldson, 1979). Further, there is evidence that childrenÕs performance on tasks involving imagined layout rotation depends on the way perspective questions are asked (Huttenlocher & Presson, 1979; Newcombe, 1997). In particular, when the question sets up a conflict between a physically present frame of reference and an imagined frame of reference, children perform poorly, but when this conflict is eliminated, same-aged children perform successfully. The effect of conflicting information on childrenÕs performance in spatial domain may reflect a phenomenon common to other cognitive domains. For example, there is evidence that early ability to make probability judgments is affected by the presence of conflicting cues. Piaget (1965) argued that young children determine the probability of drawing a particular item based on the absolute (as opposed to relative) quantity of these items in a set. More recent work (Acredolo, OÕConnor, Banks, & Horobin, 1989) showed that five-year-olds can use relative quantity to make successful probability judgments. However, when the information about absolute quantity conflicts with the information about relative quantity, children resort to the use of absolute information, which leads them to wrong responses. Whereas it is possible to eliminate conflicting cues and thus enhance the level of performance in the experimental setting, in real life people are constantly confronted with situations in which they have to weigh conflicting cues against one another. It is possible that children develop a strategy for dealing with conflicting information in a particular domain through the accumulation of experience in that domain. For example, if children rely on egocentric cues when their orientation relative to a space has changed, they will not be able to find important places and objects, and this negative feedback will highlight the importance of objective spatial cues. It is also possible that children develop a general strategy for dealing with conflict that can be applied across domains. Around five years of age children begin to solve a variety of tasks by choosing appropriate cues in the presence of conflicting evidence. Younger children have difficulty coordinating
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different pieces of information and considering alternative interpretations of a particular situation. For example, Rock and colleagues have shown that 3and 4-year-olds find it difficult to achieve different perceptions of an ambiguous figure, even when they are informed about the ambiguity of the figure (Rock, Gopnick, & Hall, 1994). Jacques and Zelazo (2001) have shown that 4-year-olds perform poorly on the task that requires sorting cards according to different dimensions whereas 5-year-olds perform well on the same task. This evidence suggests that between 4 and 5 years of age children achieve a level of cognitive flexibility that allows them to think about a situation in more than one way. The ability to solve spatial tasks involving conflicting cues may depend on the development of cognitive flexibility because these tasks require that children recognize and coordinate different spatial strategies—i.e., egocentric and objective coding of location.
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