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Toddlers Can Adaptively Change How They Categorize: Same Objects, Same Session, Two Different Categorical Distinctions

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Title: Toddlers Can Adaptively Change How They Categorize: Same Objects, Same Session, Two Different Categorical Distinctions
Language: English
Authors: Horst, Jessica S., Ellis, Ann E., Samuelson, Larissa K.
Source: Developmental Science. Jan 2009 12(1):96-105.
Availability: Wiley-Blackwell. 350 Main Street, Malden, MA 02148. Tel: 800-835-6770; Tel: 781-388-8598; Fax: 781-388-8232; e-mail: cs-journals@wiley.com; Web site: http://www.wiley.com/WileyCDA/
Peer Reviewed: Y
Physical Description: PDF
Page Count: 10
Publication Date: 2009
Document Type: Journal Articles
Reports - Evaluative
Descriptors: Toddlers, Classification, Language Acquisition, Vocabulary Development, Tactual Perception, Stimuli, Language Skills, Child Development
DOI: 10.1111/j.1467-7687.2008.00737.x
ISSN: 1363-755X
Abstract: Two experiments demonstrate that 14- to 18-month-old toddlers can adaptively change how they categorize a set of objects within a single session, and that this ability is related to vocabulary size. In both experiments, toddlers were presented with a sequential touching task with objects that could be categorized either according to some perceptually salient dimension corresponding to a taxonomic distinction (e.g. animals vs. vehicles) or to some less obvious dimension (e.g. rigid vs. deformable). In each experiment, children with larger productive vocabularies responded to both dimensions, showing evidence of sensitivity to each way of categorizing the items. Children with smaller productive vocabularies attended only to the taxonomically related categorical grouping. These experiments confirm that toddlers can adaptively shift the basis of their categorization and highlight the dynamic interaction between the child and the current task in early categorization.
Abstractor: As Provided
Number of References: 26
Entry Date: 2009
Accession Number: EJ849458
Database: ERIC
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  Value: <anid>AN0035818660;5g501jan.09;2019May28.13:50;v2.2.500</anid> <title id="AN0035818660-1">Toddlers can adaptively change how they categorize: same objects, same session, two different categorical distinctions. </title> <p>Two experiments demonstrate that 14‐ to 18‐month‐old toddlers can adaptively change how they categorize a set of objects within a single session, and that this ability is related to vocabulary size. In both experiments, toddlers were presented with a sequential touching task with objects that could be categorized either according to some perceptually salient dimension corresponding to a taxonomic distinction (e.g. animals vs. vehicles) or to some less obvious dimension (e.g. rigid vs. deformable). In each experiment, children with larger productive vocabularies responded to both dimensions, showing evidence of sensitivity to each way of categorizing the items. Children with smaller productive vocabularies attended only to the taxonomically related categorical grouping. These experiments confirm that toddlers can adaptively shift the basis of their categorization and highlight the dynamic interaction between the child and the current task in early categorization.</p> <p>Forming categories is fundamental to understanding the world. However, the features most important for categorization change from moment to moment – shape is relevant for the category 'rolling objects', but material is relevant for the category 'objects that bang'. Moreover, individual objects can be included in different categories – a plastic ball can be categorized both with 'rolling objects' and 'objects that bang'. Skilled categorizers, therefore, must recognize features constant across members of a category, but overcome the tendency to perseveratively categorize using one set of features, adaptively shifting the basis of their categorization when appropriate. Such adaptability is likely related to the kind of flexible thinking that is a hallmark of executive function in children and adults ([<reflink idref="bib12" id="ref1">12</reflink>]), increases with age ([<reflink idref="bib11" id="ref2">11</reflink>]), and is impaired in patients with frontal lobe damage ([<reflink idref="bib5" id="ref3">5</reflink>]).</p> <p>Infants do categorize differently in response to task variations. For example, when familiarized with the exact same items, infants attended to a relatively broad category (e.g. animals) or narrow category (e.g. land animals) depending on which items were encountered frequently during familiarization ([<reflink idref="bib19" id="ref4">19</reflink>]). Infants familiarized with dogs or horses differentiated those categories when a novel dog and a novel horse were presented side‐by‐side, but not when the novel items were presented sequentially ([<reflink idref="bib26" id="ref5">26</reflink>]). Toddlers categorized objects as animals and vehicles only if the functional parts (e.g. legs and wheels) were in a standard orientation ([<reflink idref="bib20" id="ref6">20</reflink>], [<reflink idref="bib21" id="ref7">21</reflink>]).</p> <p>Thus, young children adaptively categorize items in response to task and stimuli differences. However, skilled categorizers also group items along one dimension at one moment, and then switch to another dimension if the task changes. [<reflink idref="bib16" id="ref8">16</reflink>]), using sequential‐touching, found that 18‐month‐old toddlers adaptively first grouped objects into basic‐level categories and later grouped those objects into global categories. [<reflink idref="bib6" id="ref9">6</reflink>]) similarly observed that across four weekly sessions, 14‐month‐old toddlers categorized the same items as balls versus blocks <emph>and</emph> as rigid versus deformable when the rigid versus deformable distinction was demonstrated in each weekly session. However, this pattern was evident only in toddlers with relatively high receptive vocabularies; toddlers with lower receptive vocabularies focused only on the distinction between balls and blocks.</p> <p>Here we used a procedure like that of [<reflink idref="bib6" id="ref10">6</reflink>] to observe adaptive categorization within a single session. We examined whether toddlers adaptively shift their attention from one categorical distinction to another on a moment‐by‐moment basis under several experimental conditions. In Experiment 1, we tested older toddlers using a different stimulus set than that used by [<reflink idref="bib6" id="ref11">6</reflink>] to explore whether the ability to adaptively categorize is robust and independent of the particular stimuli or point in development. In Experiment 2, we investigated whether younger toddlers' ability to adaptively change how they categorize arises spontaneously or emerges in response to the specifics of the task, for example, after seeing a demonstration designed to highlight a less obvious categorical distinction.</p> <hd id="AN0035818660-2">Experiment 1</hd> <p>Experiment 1 assessed 18‐month‐old toddlers' changing attention to the animal/vehicle and rolling/non‐rolling object distinctions. [<reflink idref="bib20" id="ref12">20</reflink>], [<reflink idref="bib21" id="ref13">21</reflink>]) observed that children at this age were sensitive to contrasts between animals versus vehicles and objects with legs versus wheels. Like [<reflink idref="bib6" id="ref14">6</reflink>]), we included a vocabulary measure to test the relation between vocabulary and adaptive categorization. Based on that study, we predicted that vocabulary would be related to toddlers' attention to the less salient dimension, but not to their attention to appearance. Although Ellis and Oakes used receptive vocabulary, here we used productive vocabulary because (<reflink idref="bib1" id="ref15">1</reflink>) parental accounts of productive vocabulary have been found to be reliable (e.g. [<reflink idref="bib3" id="ref16">3</reflink>]; but see [<reflink idref="bib4" id="ref17">4</reflink>]); and (<reflink idref="bib2" id="ref18">2</reflink>) measuring productive vocabulary is more appropriate for this age group. Because productive and receptive vocabularies are highly correlated ([<reflink idref="bib7" id="ref19">7</reflink>]), the results we obtain here for productive vocabulary should be similar to those obtained by Ellis and Oakes with receptive vocabulary.</p> <hd id="AN0035818660-3">Method</hd> <p></p> <hd id="AN0035818660-4">Participants</hd> <p>Thirty‐three healthy, monolingual 18‐month‐old toddlers participated (12 girls, <emph>M</emph> = 78.46 weeks, <emph>SD</emph> = 1.60 weeks, range: 75.50–84.10 weeks). Twenty toddlers (seven girls) were tested at the University of Iowa and 13 toddlers (five girls) were tested at Grinnell College. The groups did not differ in age, vocabulary size, or number of touches (all <emph>p</emph>s >.11). Data from two additional toddlers were excluded due to experimenter error and equipment failure. Here and in Experiment 2 children were recruited as reported by [<reflink idref="bib6" id="ref20">6</reflink>]).</p> <hd id="AN0035818660-5">Stimuli</hd> <p>The stimuli were four animals (a tiger, an elephant, a horse and a giraffe) and four vehicles (a green car, a police car, a motorcycle and a bulldozer), ranging from 8.50 cm to 16.50 cm in length and 3.30 cm and 16.50 cm in height (Figure 1). Each vehicle had visible wheels, although only two had functional wheels (the wheels of the others were integral parts of the body and could not rotate). Two animals (tiger and elephant) had functional wheels that were almost completely hidden underneath the animal (only a fraction of the wheels was visible when the animal was on its side or upside down). Thus two animals and two vehicles could roll. Because the non‐rolling vehicles had visible wheels and the rolling animals did not, no single visible feature reliably predicted rolling. A small wooden ramp was used to demonstrate rolling.</p> <p>Graph: 1 Stimuli used in both experiments. The left panel depicts the stimuli used in Experiment 1. The objects in front of the ramp can roll, the objects on the ramp cannot. The right panel depicts the stimuli used in Experiment 2. The objects to the right of the frog can‐crusher are rigid, the other objects are deformable.</p> <hd id="AN0035818660-6">Procedure</hd> <p>Toddlers sat directly across from the experimenter, on a parent's lap or in a booster seat next to a parent. A video camera captured the child's head and upper body and the tabletop. Parents encouraged their children to play with the toys if necessary but avoided naming them. Parents completed the MacArthur‐Bates Infant CDI.</p> <p>Following two warm‐up tasks (removing a poker chip from a bottle and stacking blocks, approximately 4 min), the experimenter dumped the toys onto a wooden tray (most toys were upright or on their sides; typically only the vehicles' wheels were visible), touched the objects (ensuring they were within the child's reach) and slid the tray to the child asking 'Can you play with these?' The child was allowed to manipulate the objects for 2 minutes (timed with a hand‐held stop‐watch). The experimenter touched all the objects saying 'Can you play with these?' when replacing any object that fell out of the child's reach, if the child failed to touch any objects, or if the child attended exclusively to one object. Otherwise the experimenter had minimal interactions with the child.</p> <p>After 2 minutes, the experimenter retrieved the objects and, in a predetermined order (different for each child), demonstrated whether each object could roll. For each rolling object the experimenter (<reflink idref="bib1" id="ref21">1</reflink>) announced 'Watch, this one rolls', (<reflink idref="bib2" id="ref22">2</reflink>) set it on the ramp, (<reflink idref="bib3" id="ref23">3</reflink>) retrieved it after it rolled down the ramp, (<reflink idref="bib4" id="ref24">4</reflink>) repeated the phrase and action, and (<reflink idref="bib4" id="ref25">4</reflink>) left the object at the foot of the ramp. For each non‐rolling object the experimenter (<reflink idref="bib1" id="ref26">1</reflink>) announced 'Watch, this one stops', (<reflink idref="bib2" id="ref27">2</reflink>) set it on the ramp, (<reflink idref="bib3" id="ref28">3</reflink>) after a pause repeated the phrase and action, and (<reflink idref="bib4" id="ref29">4</reflink>) set the object at the foot of the ramp. It was not clear whether this wording would influence toddlers' performance – the 15 children reported as knowing the word 'roll' and 23 children reported as knowing the word 'stop' did not differ from those children who did not know either word in overall vocabulary, age, or performance in the main task. After the demonstration, a second 2‐minute sequential‐touching phase was administered.</p> <hd id="AN0035818660-7">Coding</hd> <p>Naïve coders recorded the order of the objects touched for both sequential‐touching phases from videotape as described by [<reflink idref="bib6" id="ref30">6</reflink>]). Two observers coded at least 20% of the videotapes for each study. Agreement for the order in which objects were touched was high, <emph>M</emph> > 92%, <emph>SD</emph> < 8.56.</p> <hd id="AN0035818660-8">Results</hd> <p>We used several analytic strategies to examine our main prediction that vocabulary and adaptively shifting the basis of categorization would be related. From each infant's touching patterns, we calculated the traditional mean‐run‐length (MRL, e.g. [<reflink idref="bib20" id="ref31">20</reflink>]1 and the newer mean sequence‐length ([<reflink idref="bib16" id="ref32">16</reflink>]; [<reflink idref="bib24" id="ref33">24</reflink>]). MRL is calculated by dividing the total number of touches by the number of runs (sequences of touches to the same category – e.g. three successive touches to animals, four successive touches to things that roll). MSL is calculated by dividing a toddler's number of touches to a category by the number of runs to that category. Unlike MRLs, therefore, MSLs are based on a <emph>category</emph> (e.g. animals) rather than a <emph>categorical distinction</emph> (e.g. animals vs. vehicles). It has been argued that MSLs are more sensitive measures of infants'<emph>categorization</emph> because they are independent of behavior to other categories or overall number of touches. To allow comparisons with studies using both types of measure, we evaluated group responding using MRLs and individual infants' responding using MSL.</p> <p>First, we calculated correlations between vocabulary and MRLs calculated separately for the appearance‐based (animals vs. vehicles) and function‐based (rolls vs. does not roll) distinctions before and after the demonstration (see Table 1). Before the demonstration, neither MRL was related to vocabulary. After the demonstration, however, vocabulary was significantly correlated with both MRLs. Increases in vocabulary were associated with smaller appearance‐based MRLs and larger function‐based MRLs. Thus, infants with larger vocabularies appeared to be more attentive to function and less attentive to appearance after the demonstration than were toddlers with smaller vocabularies.</p> <p>1 Correlations between productive vocabulary and MRLs before and after the demonstrations for Experiments 1 and 2</p> <p> <ephtml> <table><thead valign="bottom"><tr><th /><th>Experiment 1</th><th>Experiment 2</th></tr><tr><th><italic>r</italic></th><th><italic>p</italic></th><th><italic>N</italic></th><th>Material demonstration</th><th>Appearance demonstration</th></tr><tr><th><italic>r</italic></th><th><italic>p</italic></th><th><italic>N</italic></th><th><italic>r</italic></th><th><italic>p</italic></th><th><italic>N</italic></th></tr></thead><tbody valign="top"><tr><td>Appearance MRLs</td></tr><tr><td> Pre‐demonstration</td><td>−.04</td><td>.84</td><td>33</td><td> .17</td><td>.44</td><td>24</td><td>−.27</td><td>.21</td><td>24</td></tr><tr><td> Post‐demonstration</td><td>−.36</td><td>.04</td><td>33</td><td>−.13</td><td>.56</td><td>24</td><td>−.12</td><td>.57</td><td>24</td></tr><tr><td>Functional/material MRLs</td></tr><tr><td> Pre‐demonstration</td><td> .05</td><td>.79</td><td>33</td><td>−.02</td><td>.93</td><td>24</td><td> .22</td><td>.31</td><td>24</td></tr><tr><td> Post‐demonstration</td><td> .52</td><td>.002</td><td>33</td><td> .51</td><td>.01</td><td>24</td><td>−.17</td><td>.44</td><td>24</td></tr></tbody></table> </ephtml> </p> <p>Second, we assigned toddlers to vocabulary groups based on a median split of their productive vocabularies (see Table 2). This division resulted in two groups that differed significantly in productive vocabulary, <emph>t</emph>(<reflink idref="bib31" id="ref34">31</reflink>) = 5.75, <emph>p</emph> <.0001, two‐tailed, <emph>d</emph> = 1.98, but not in age, <emph>p</emph> >.70.</p> <p>2 Productive vocabularies for toddlers in Experiment 1. Toddlers were assigned to the two groups based on the sample median and natural breaks in the vocabulary range</p> <p> <ephtml> <table><thead valign="bottom"><tr><th /><th>High‐vocabulary group</th><th>Low‐vocabulary group</th></tr></thead><tbody valign="top"><tr><td>Vocabulary</td></tr><tr><td>  <italic>M</italic></td><td>105.38 words</td><td>27.76 words</td></tr><tr><td>  <italic>SD</italic></td><td>52.60 words</td><td>17.77 words</td></tr><tr><td>  Range</td><td>55.00–219.00 words</td><td>2.00–49.00 words</td></tr><tr><td>Age</td></tr><tr><td>  <italic>M</italic></td><td>78.86 weeks</td><td>78.09 weeks</td></tr><tr><td> <italic> SD</italic></td><td>1.88 weeks</td><td>1.22 weeks</td></tr><tr><td>  Range</td><td>76.43–84.10 weeks</td><td>75.50–80.29 weeks</td></tr><tr><td><italic>N</italic></td><td>16</td><td>17</td></tr></tbody></table> </ephtml> </p> <p>A mixed‐design Analyses of Variance (ANOVA) on the appearance‐based MRL with Demonstration (pre‐, post‐) as the repeated measure and Vocabulary Group (high, low) as the between‐subjects factor yielded no significant effects (see Figure 2, left panel). Thus, in contrast with the correlations just reported, the ANOVA did not provide evidence that appearance‐based MRL was related to vocabulary or the demonstration.</p> <p>Graph: 2 Average appearance‐based MRLs (left panel) and function‐based MRLs (right panel) for Experiment 1 by vocabulary group. Bars indicated by an asterisk were significantly different, p <.05. Error bars represent one standard error.</p> <p>An identical ANOVA conducted on function‐based MRLs, in contrast, was consistent with the correlations. The main effect of Vocabulary Group was significant, <emph>F</emph>(<reflink idref="bib1" id="ref35">1</reflink>, 31) = 4.49, <emph>p</emph> <.05; high‐vocabulary toddlers exhibited greater function‐based MRLs than low‐vocabulary toddlers (Figure 2, right panel). Interestingly, unlike the correlations, this effect was found for the means across the pre‐ and post‐demonstration parts of the session. In general, then, both the correlations and this ANOVA revealed that attention to function was related to vocabulary, consistent with higher vocabulary toddlers being more adaptive.</p> <p>This conclusion was corroborated with an examination of individual toddlers' touching patterns using the transitional probability of their mean sequence‐lengths (MSL; [<reflink idref="bib24" id="ref36">24</reflink>]). We calculated the probability that a toddler attended to each category (using <emph>p</emph> =.10; [<reflink idref="bib14" id="ref37">14</reflink>]; [<reflink idref="bib24" id="ref38">24</reflink>]). As a first step, we classified toddlers as <emph>single</emph> categorizers for a distinction (e.g. appearance) if they attended to only one category (e.g. animals but not vehicles), <emph>dual</emph> categorizers for a distinction if they attended to both categories (e.g. things that roll and things that do not roll), and <emph>non‐categorizers</emph> for a distinction if they did not attend to either category.</p> <p>The proportions of toddlers in each group are given in Table 3. Consistent with the analyses of the MRLs, the proportion of high‐vocabulary toddlers attending to function (things that roll, things that don't roll) increased from 56.25% before the demonstration to 81.25% (single and dual categorizers combined) after the demonstration. The proportion of high‐vocabulary toddlers attending to appearance (animal, vehicle) remained stable, as did the proportion of low‐vocabulary toddlers attending to either appearance or function. Thus, these descriptive data confirm the conclusion from the group data; only high‐vocabulary toddlers increased attention to function after the demonstration.</p> <p>3 Proportion of children who were classified as single, dual or none categorizers for the appearance and function/material dimensions in both experiments</p> <p> <ephtml> <table><thead valign="bottom"><tr><th /><th>Experiment 1</th><th>Experiment 2</th></tr><tr><th /><th>Material demonstration</th><th>Appearance demonstration</th></tr><tr><th>none</th><th>single</th><th>dual</th><th>none</th><th>single</th><th>dual</th><th>none</th><th>single</th><th>dual</th></tr></thead><tbody valign="top"><tr><td>Appearance dimension</td></tr><tr><td><italic>Low vocabulary</italic></td></tr><tr><td> Pre‐demonstration</td><td>35.29</td><td>64.71</td><td> 0.00</td><td>18.18</td><td>63.64</td><td>18.18</td><td>30.77</td><td>53.85</td><td>15.38</td></tr><tr><td> Post‐demonstration</td><td>41.18</td><td>41.18</td><td>17.65</td><td>36.36</td><td>45.45</td><td>18.18</td><td>30.77</td><td>46.15</td><td>23.08</td></tr><tr><td><italic>High vocabulary </italic></td></tr><tr><td> Pre‐demonstration</td><td>31.25</td><td>56.25</td><td>12.50</td><td> 7.69</td><td>76.92</td><td>15.38</td><td> 9.09</td><td>81.82</td><td> 9.09</td></tr><tr><td> Post‐demonstration</td><td>31.25</td><td>56.25</td><td>12.50</td><td> 7.69</td><td>84.62</td><td> 7.69</td><td>27.27</td><td>63.64</td><td> 9.09</td></tr><tr><td>Function/material dimension</td></tr><tr><td><italic>Low vocabulary</italic></td></tr><tr><td> Pre‐demonstration</td><td>41.18</td><td>47.06</td><td>11.76</td><td>27.27</td><td>54.55</td><td>18.18</td><td>23.08</td><td>53.85</td><td>23.08</td></tr><tr><td> Post‐demonstration</td><td>47.06</td><td>41.18</td><td>11.76</td><td>54.55</td><td>36.36</td><td> 9.09</td><td>38.46</td><td>46.15</td><td>15.38</td></tr><tr><td><italic>High vocabulary </italic></td></tr><tr><td> Pre‐demonstration</td><td>43.75</td><td>56.25</td><td> 0.00</td><td>38.46</td><td>53.85</td><td> 7.69</td><td>36.36</td><td>45.45</td><td>18.18</td></tr><tr><td> Post‐demonstration</td><td>18.75</td><td>62.50</td><td>18.75</td><td>46.15</td><td>38.46</td><td>15.38</td><td>36.36</td><td>36.36</td><td>27.27</td></tr></tbody></table> </ephtml> </p> <p>We can also examine how individual toddlers <emph>changed</emph> their categorization. First, we established children's pattern of attention <emph>within</emph> dimensions from before to after the demonstration: children could <emph>increase</emph> attention to appearance or function after the demonstration (e.g. a single before and a dual categorizer after the demonstration), <emph>decrease</emph> attention to appearance or function after the demonstration (e.g. a dual before and a single categorizer after the demonstration), or be <emph>stable </emph>with respect to a dimension (exhibiting the same classification before and after the demonstration; toddlers who switched categories within a distinction – e.g. animals before and vehicles after the demonstration – but remained a single categorizer were classified as stable because they consistently attended to only one category). Note that children's change (or lack of change) with respect to one distinction was independent of their behavior toward the other distinction – e.g. a child could decrease attention to appearance and increase attention to function.</p> <p>We then assigned children to one of three groups. <emph>Function‐focused</emph> toddlers' attention to function increased while at the same time their attention to appearance decreased or remained stable. They effectively became more interested in function and less interested in appearance as the session progressed, adapting their categorizations to the information provided in the task. <emph>Appearance‐focused </emph>toddlers showed the opposite pattern – their attention to appearance increased or remained stable while at the same time their attention to function decreased or remained stable. They perseveratively attended to appearance despite the fact that the demonstration highlighted function. <emph>Neither‐focused</emph> children did not fit either pattern (two children from the low‐vocabulary group never showed evidence of categorization and thus were not included in any of these groups).</p> <p>Similar proportions of high‐ and low‐vocabulary toddlers were neither‐focused (see Table 4). However, more low‐vocabulary children were appearance‐focused than function‐focused, primarily maintaining or increasing attention to appearance while decreasing attention to function. The high‐vocabulary children, in contrast, generally maintained or increased attention function while decreasing attention to appearance. Thus, the analyses of the group data and of the individual data lead to the same conclusion: high‐vocabulary toddlers were more likely than low‐vocabulary toddlers to adaptively categorize in response to the task.</p> <p>4 Proportion of children who focused on appearance or function after the demonstration in Experiment 1</p> <p> <ephtml> <table><thead valign="bottom"><tr><th>Group Subgroup</th><th>Low vocabulary</th><th>High vocabulary</th></tr></thead><tbody valign="top"><tr><td>Function‐focused</td><td>26.67</td><td>50.00</td></tr><tr><td> increase function, decrease appearance</td><td>13.33</td><td>18.75</td></tr><tr><td> stable appearance</td><td> 6.67</td><td>18.75</td></tr><tr><td> stable function, decrease appearance</td><td> 6.67</td><td>12.50</td></tr><tr><td>Appearance‐focused</td><td>46.66</td><td>18.75</td></tr><tr><td> increase appearance, decrease function</td><td>13.33</td><td> 6.25</td></tr><tr><td> stable function</td><td>13.33</td><td>12.50</td></tr><tr><td> stable appearance, decrease function</td><td>20.00</td><td> 0.00</td></tr><tr><td>Neither‐focused</td><td>26.67</td><td>31.25</td></tr><tr><td> decrease appearance, decrease function</td><td> 6.67</td><td> 0.00</td></tr><tr><td> increase appearance, increase function</td><td> 6.67</td><td> 6.25</td></tr><tr><td> stable appearance, stable function</td><td>13.33</td><td>25.00</td></tr></tbody></table> </ephtml> </p> <hd id="AN0035818660-9">Discussion</hd> <p>These results demonstrate that toddlers can adaptively categorize the same objects in two ways within a single session. Eighteen‐month‐old toddlers with larger vocabularies were more likely than their peers to attend to function after a relevant demonstration.</p> <p>In Experiment 2 we extended our understanding of this relation by conducting an experiment that would complement both Experiment 1 and the [<reflink idref="bib6" id="ref39">6</reflink>]) study. Specifically, we sought to replicate the general finding from Experiment 1 with toddlers closer in age to Ellis and Oakes using the categorical distinctions used in that study. In addition, in Experiment 2 we examined whether adaptive categorization by 14‐ to 16‐month‐old toddlers is spontaneous or emerges as a response to the demonstration.</p> <hd id="AN0035818660-10">Experiment 2</hd> <p></p> <hd id="AN0035818660-11">Method</hd> <p></p> <hd id="AN0035818660-12">Participants</hd> <p>Twenty‐three 14‐month‐old (nine girls, <emph>M</emph> = 63.10 weeks, <emph>SD</emph> = 1.04 weeks, range: 61.00–64.71 weeks) and 25 16‐month‐old (15 girls, <emph>M</emph> = 71.51 weeks, <emph>SD</emph> = 1.28 weeks, range: 69.86–75.43 weeks) monolingual toddlers participated at the University of Iowa. Data from five additional toddlers were not included in the final analyses due to parental interference (<emph>n</emph> = 2), fussiness (<emph>n</emph> = 2), and lack of interest (<emph>n</emph> = 1).</p> <hd id="AN0035818660-13">Stimuli</hd> <p>The stimuli were four balls (a pink plastic ball, a blue foam ball, a green rubber ball and a white wiffle ball) and four blocks (a white fuzzy cube, an orange plastic block, a red plastic block and a plastic block with a picture on each side), ranging in size from 5.50 to 8.00 cm (see Figure 1).2 Two objects from each group were deformable and two were rigid. The 'frog' can‐crusher used by [<reflink idref="bib6" id="ref40">6</reflink>]) was also used.</p> <hd id="AN0035818660-14">Procedure</hd> <p>We administered two warm‐up tasks: a tea‐party with the experimenter (approximately 2 minutes), and, as in [<reflink idref="bib6" id="ref41">6</reflink>]), an animals/vehicles sequential‐touching task (approximately 2 minutes). Note that because the animals/vehicles can be categorized on the basis of perceptual, conceptual or functional similarity, this initial task would not bias toddlers to attend to overall appearance or material, but rather would encourage them to touch the stimuli, therefore increasing their participation in our main task.</p> <p>The main task was the same as Experiment 1 except that there were two demonstration conditions. In the <emph>material‐demonstration</emph> condition, the experimenter (<reflink idref="bib1" id="ref42">1</reflink>) placed the frog can‐crusher on the table, (<reflink idref="bib2" id="ref43">2</reflink>) positioned ball and block inside the can‐crusher saying 'Look what this does!' and (<reflink idref="bib3" id="ref44">3</reflink>) attempted to squish it by pressing down on the can‐crusher. In the <emph>appearance demonstration</emph> condition, the experimenter (<reflink idref="bib1" id="ref45">1</reflink>) held up each ball and block and (<reflink idref="bib2" id="ref46">2</reflink>) said 'Look at this!' Note we still used two categorical distinctions in this study: one was apparent simply by looking at the objects (balls vs. blocks) while the other required the toddlers to interact with the objects (hard vs. soft).</p> <hd id="AN0035818660-15">Results</hd> <p>Initial analyses revealed no effect of age on performance, all <emph>p</emph>s >.33; this variable was not included in any of the reported analyses.</p> <p>As in Experiment 1, we examined group trends using MRLs and patterns of individual touching using MSLs. We conducted the correlations between appearance‐ and material‐MRLs and vocabulary separately for the two demonstration conditions.3 None of these correlations were significant for the appearance‐demonstration condition (Table 1). In the material‐demonstration condition, in contrast, vocabulary was positively correlated with material‐based MRLs after the demonstration. Thus, attention to the less obvious property appears to be related to vocabulary, but only if that property was demonstrated. Indeed, the correlation between vocabulary and material‐based MRL for the material‐demonstration condition was significantly greater than that for the appearance‐demonstration condition,<emph> Z</emph> = 2.47, <emph>p</emph> =.01, two‐tailed.</p> <p>Next, we split the sample based on median vocabulary (see Table 5 for the resulting four groups). An ANOVA conducted on vocabulary scores with Demonstration Condition (material, appearance) and Vocabulary Group (high, low) as between‐subjects factors revealed only a main effect of Vocabulary Group, <emph>F</emph>(<reflink idref="bib1" id="ref47">1</reflink>, 44) = 41.54, <emph>p</emph> <.0001, confirming that the demonstration groups did not differ in vocabulary.</p> <p>5 Productive vocabularies for toddlers in Experiment 2. Toddlers were assigned to the two groups based on the sample median and natural breaks in the vocabulary range</p> <p> <ephtml> <table><thead valign="bottom"><tr><th>Demonstration condition <italic>Measure</italic></th><th /><th>High‐vocabulary group</th><th>Low‐vocabulary group</th></tr></thead><tbody valign="top"><tr><td>Material demonstration</td></tr><tr><td> <italic>Vocabulary</italic> </td><td><italic>M</italic></td><td>28.69 words</td><td>6.09 words</td></tr><tr><td><italic>SD</italic></td><td>18.84 words</td><td>4.97 words</td></tr><tr><td>Range</td><td>15.00–64.00 words</td><td>0.00–11.00 words</td></tr><tr><td> <italic>Age </italic></td><td><italic>M</italic></td><td>68.16 weeks</td><td>66.16 weeks</td></tr><tr><td><italic>SD</italic></td><td>4.41 weeks</td><td>4.37 weeks</td></tr><tr><td>Range</td><td>61.86–73.86 weeks</td><td>61.57–72.57 weeks</td></tr><tr><td> <italic>N</italic></td><td /><td>13</td><td>11</td></tr><tr><td>Appearance demonstration</td></tr><tr><td> <italic>Vocabulary </italic></td><td><italic>M</italic></td><td>28.09 words</td><td>6.15 words</td></tr><tr><td><italic>SD</italic></td><td>12.46 words</td><td>4.08 words</td></tr><tr><td>Range</td><td>16.00–43.00 words</td><td>0.00–14.00 words</td></tr><tr><td> <italic>Age </italic></td><td><italic>M</italic></td><td>68.56 weeks</td><td>67.64 weeks</td></tr><tr><td><italic>SD</italic></td><td>3.90 weeks</td><td>4.94 weeks</td></tr><tr><td>Range</td><td>62.57–73.57 weeks</td><td>61.00–75.43 weeks</td></tr><tr><td> <italic>N</italic></td><td /><td>11</td><td>13</td></tr></tbody></table> </ephtml> </p> <p>The joint influences of vocabulary and demonstration on toddlers' adaptive categorization was examined with separate mixed‐design ANOVAs on appearance‐based and material‐based MRLs with Demonstration (pre‐, post‐) as the repeated measure and Demonstration Condition and Vocabulary Group as between‐subjects factors. The ANOVA on appearance‐based MRLs yielded a Condition by Vocabulary Group interaction, <emph>F</emph>(<reflink idref="bib1" id="ref48">1</reflink>, 44) = 4.42, <emph>p </emph><.05, due to toddlers in the high‐vocabulary/material‐demonstration group having the largest appearance‐based MRLs (<emph>M</emph> = 2.89, <emph>SD</emph> = 1.19), followed by toddlers in the low‐vocabulary/appearance‐demonstration group (<emph>M</emph> = 2.25, <emph>SD</emph> =.79), the low‐vocabulary/material‐demonstration group (<emph>M</emph> = 2.20, <emph>SD</emph> =.95) and the high‐vocabulary/appearance‐ demonstration group (<emph>M</emph> = 1.85, <emph>SD</emph> =.42). This unexpected interaction did not appear to reflect the responding of the group as a whole. Rather, two children in the high‐vocabulary/material‐demonstration group had appearance‐based MRLs of > 7.66 before the demonstration. Thus, the significant interaction is neither clear nor meaningful. We elected to include the data from these toddlers in all the analyses, however, because their striking attention to appearance works against our hypothesis of attention to material.</p> <p>As we expected, attention to material was restricted to high‐vocabulary toddlers who saw the material demonstration. The ANOVA on material‐based MRLs yielded only a significant Demonstration by Condition by Vocabulary Group interaction, <emph>F</emph>(<reflink idref="bib1" id="ref49">1</reflink>, 44) = 5.35, <emph>p</emph> <.05. Separate ANOVAs conducted for each vocabulary group revealed no effects for the low‐vocabulary group, all <emph>p</emph>s >.33, but a significant Demonstration by Condition interaction for the high‐vocabulary group, <emph>F</emph>(<reflink idref="bib1" id="ref50">1</reflink>, 22) = 4.36, <emph>p</emph> =.05. Thus, the type of demonstration influenced how material‐based MRLs changed from before to after the demonstration for toddlers with higher vocabularies (see Figure 3). We replicated [<reflink idref="bib6" id="ref51">6</reflink>]) finding that high‐vocabulary toddlers attended to appearance before the demonstrations and material after the demonstrations.</p> <p>Graph: 3 Average material‐based MRLs for Experiment 2 by vocabulary level, demonstration group, and pre‐ versus post‐demonstration. Error bars represent one standard error.</p> <p>Individual infants' touching patterns using MSLs (see Table 3) revealed that in both demonstration conditions, a relatively higher proportion of high‐vocabulary children than low‐vocabulary children attended to appearance both before and after the demonstration. In general, therefore, toddlers with larger vocabularies were more attentive to appearance similarities than toddlers with smaller vocabularies. In contrast, the proportion of toddlers who attended to material was not related to vocabulary size or demonstration condition.</p> <p>Next, using the criteria described in Experiment 1, we classified toddlers as material‐focused, appearance‐focused, or neither‐focused (data from two children from the low‐vocabulary groups, one from each condition, were excluded because they never showed evidence of categorization). Regardless of demonstration condition, high‐vocabulary toddlers were more likely than low‐vocabulary toddlers to be material‐focused (see Table 6). Indeed, a three‐way Contingency Test with Demonstration Condition (material, appearance), Vocabulary (high, low) and Focus Group (material, appearance) conducted on the subset of toddlers who did have a focus revealed a significant Vocabulary by Focus Group interaction, <emph>G</emph><sups>2</sups>(<reflink idref="bib1" id="ref52">1</reflink>) = 3.94, <emph>p</emph> <.05. Thus, vocabulary was related to toddlers' changing attention to material across the session. Toddlers with larger vocabularies were more likely to increase their attention to material than children with smaller vocabularies. The three‐way Contingency did not reach significance, <emph>G</emph><sups>2</sups>(<reflink idref="bib4" id="ref53">4</reflink>) = 5.96, <emph>p</emph> =.20. Therefore, the evaluation of the individual touching patterns confirmed the conclusion from the analyses of the group performance that high‐vocabulary toddlers were more attentive to the less obvious distinction than were the low‐vocabulary ones. These analyses did not confirm, however, that this effect was primarily observed when that feature was actually demonstrated.</p> <p>6 Proportion of children who focused on appearance or material after the demonstration in Experiment 2</p> <p> <ephtml> <table><thead valign="bottom"><tr><th>Group Subgroup</th><th>Material demonstration</th><th>Appearance demonstration</th></tr><tr><th>Low vocab</th><th>High vocab</th><th>Low vocab</th><th>High vocab</th></tr></thead><tbody valign="top"><tr><td>Material‐focused</td><td>20.00</td><td>30.76</td><td>16.66</td><td>45.45</td></tr><tr><td> increase material, decrease appearance</td><td>10.00</td><td> 7.69</td><td> 0.00</td><td>18.18</td></tr><tr><td> stable appearance</td><td> 0.00</td><td> 7.69</td><td> 8.33</td><td>27.27</td></tr><tr><td> stable material, decrease appearance</td><td>10.00</td><td>15.38</td><td> 8.33</td><td> 0.00</td></tr><tr><td>Appearance‐focused</td><td>30.00</td><td>23.07</td><td>50.00</td><td>27.27</td></tr><tr><td> increase appearance, decrease material</td><td>10.00</td><td> 0.00</td><td> 0.00</td><td> 0.00</td></tr><tr><td> stable material</td><td> 0.00</td><td> 7.69</td><td>25.00</td><td>18.18</td></tr><tr><td> stable appearance, decrease material</td><td>20.00</td><td>15.38</td><td>25.00</td><td> 9.09</td></tr><tr><td>Neither‐focused</td><td>50.00</td><td>46.15</td><td>16.67</td><td>27.27</td></tr><tr><td> decrease appearance, decrease material</td><td>10.00</td><td> 0.00</td><td>16.67</td><td> 0.00</td></tr><tr><td> increase appearance, increase material</td><td>10.00</td><td> 7.69</td><td>16.67</td><td> 9.09</td></tr><tr><td> stable appearance, stable material</td><td>30.00</td><td>38.46</td><td> 0.00</td><td>18.18</td></tr></tbody></table> </ephtml> </p> <hd id="AN0035818660-16">Discussion</hd> <p>Even young toddlers adaptively categorize within a single session. Such categorization is related to vocabulary level, and perhaps to the information provided in the task. Toddlers with larger vocabularies responded more to a less obvious material distinction than toddlers with smaller vocabularies. Evaluation of the group performance suggested that this relation between vocabulary size and attention to deformability was particularly strong when that distinction was demonstrated.</p> <hd id="AN0035818660-17">General discussion</hd> <p>Toddlers are excellent categorizers. They can detect commonalities within and distinguish between categories. However, categories are not mutually exclusive; an object can belong to many categories at the same time. Which category is most relevant depends on the current situation. Thus, to be skilled categorizers, toddlers must be able to adapt their categorization strategy and the categorical distinctions to which they attend in response to task variations. We demonstrated that toddlers with relatively larger productive vocabularies adaptively categorized the same objects using a relatively obvious (e.g. shape) and a less obvious (e.g. material) dimension in a single experimental session. Young children with larger productive vocabularies relative to their same‐age peers have an impressive ability to quickly reorganize how they group objects.</p> <p>There are at least three explanations for the link between vocabulary and adaptive categorization. First, adaptive categorization may emerge from language development. Learning the meanings of many different words requires that children attend to many different commonalities; consequently children may become sensitive to more types of commonalities among objects. As children learn more words, they can categorize objects in different ways (e.g. [<reflink idref="bib1" id="ref54">1</reflink>]; [<reflink idref="bib25" id="ref55">25</reflink>]).</p> <p>Second, the link between language and adaptive categorization may reflect advances in categorization abilities encouraging vocabulary development (see e.g. [<reflink idref="bib9" id="ref56">9</reflink>], [<reflink idref="bib10" id="ref57">10</reflink>]). Children's learning of new words may be made possible through toddlers' increasing sensitivity to new kinds of categorical contrasts. Regardless of the direction of the effect, the relation between vocabulary and adaptive categorization does not appear to reflect the relation between a specific language milestone and categorization. For example, our results do not reflect children who have achieved the vocabulary spurt (see [<reflink idref="bib8" id="ref58">8</reflink>]) demonstrating more adaptive categorization than children who have not. The vocabulary spurt is typically defined by the appearance of 50 words in the productive vocabulary. Our high‐vocabulary groups had fewer than 50 words in their productive vocabularies (indeed, only 19 toddlers in our entire sample produced 50 or more words); therefore, the relation we observed was not dependent on whether children had achieved this particular milestone.</p> <p>An even more striking illustration that adaptive categorization does not emerge once a particular language milestone has been achieved is a comparison of the low‐vocabulary group in Experiment 1 and the high‐vocabulary group in Experiment 2. Both groups of children produced approximately 30 words, and yet the group from Experiment 1 was less attentive to the less obvious distinction than was the group from Experiment 2. The point is that the same relation between children's vocabulary and adaptive categorization was observed at two points in vocabulary development (with infants of different ages), and with two different stimulus sets and categorical contrasts.</p> <p>Rather than a direct link between vocabulary and adaptive categorization, the associations shown here may reflect the influence of another more general cognitive process on both vocabulary acquisition and adaptive categorization. Candidate processes are the ability to detect and attend to regularities, attention to salient cues, or general attentional capacity. Because here we observed the same relation between vocabulary and adaptive categorization at two different points in vocabulary development, our results are most consistent with this third alternative. If adaptive categorization was a product of language development, or if language development requires specific categorization skills, then vocabulary and categorization should be related at one point in development – we should not see this relation re‐emerging at different points in development. Of course, we did not directly examine cognitive ability. A clear direction for future research is to systematically investigate this possibility.</p> <p>Why did adaptive categorization emerge at different points in development in the two experiments? Shifting the basis of the categories may have been more difficult in Experiment 1 for a number of reasons. The objects in Experiment 1 came from two superordinate categories, whereas the objects in Experiment 2 came from two basic‐level categories. In addition, the items within the taxonomic categories of Experiment 1 may have been more variable than those within the shape categories of Experiment 2. Further, the less obvious distinctions in the two experiments are quite different, and the same skills and strategies may not be involved in these two groupings. Infants' categorization of stimuli depends on the interaction of factors such as infant age, stimulus presentation procedures, and stimulus variability (e.g. [<reflink idref="bib2" id="ref59">2</reflink>]; [<reflink idref="bib15" id="ref60">15</reflink>]; [<reflink idref="bib18" id="ref61">18</reflink>]). Nonetheless, our data clearly suggest that task variations led to differences in the level of adaptive categorization, even when toddlers had very similar vocabularies.</p> <p>Interestingly, the evaluation of the group performance and individual performances did not always support the same conclusion. In general, toddlers with relatively high vocabularies were more attentive to the less obvious categorical distinction, even increasing attention to this distinction over time. However, in Experiment 2, examination of the group performance (using MRL) indicated that the type of demonstration played a role in this increase; examination of the individual touching patterns (using MSL) did not. MSL may be a better measure because it is more theoretically grounded and less arbitrary than MRL ([<reflink idref="bib16" id="ref62">16</reflink>]; [<reflink idref="bib24" id="ref63">24</reflink>]). A full evaluation of the differences between these measures is beyond the scope of this paper. However, it is common to report both individual and group data when using sequential touching, and to draw conclusions from the general pattern (e.g. [<reflink idref="bib13" id="ref64">13</reflink>]; [<reflink idref="bib17" id="ref65">17</reflink>]). However, in the present experiments, conclusions about the effect of the different types of demonstration in Experiment 2 should be drawn with caution.</p> <p>Overall, the present results suggest that adaptive categorization is a product of the interaction between the child and the task. This interpretation is consistent with a growing body of research suggesting that children's behavior should not be viewed as a reflection of static knowledge, but instead as a reflection of fluid and dynamic understanding that emerges in the moment as a product of the abilities the child brings to the task, what the child has just experienced, and the information available to the child in the task (e.g. [<reflink idref="bib22" id="ref66">22</reflink>]; [<reflink idref="bib23" id="ref67">23</reflink>]). Importantly, the present results suggest that understanding the development of these most fundamental aspects of cognition – such as adaptively categorizing in response to task variations – requires considering these complex child–task interactions.</p> <hd id="AN0035818660-18">Acknowledgements</hd> <p>Portions of these data were presented at the 2003 and 2005 Biennial Meetings of the Society for Research in Child Development, Tampa, FL and Atlanta, GA. This research and preparation of this manuscript were made possible by NIH grants, HD45713 to LKS, and HD49840, HD49143 and MH64020 to LMO and grants to AEE from Grinnell College. We would like to express our appreciation to Shaena Stille, Ryan Brink, Laura M. Phillip, Clay Y. Collins, Melanie K. Parker, Eleanora E.T. Cacciola and Marie Tan Kiak Li, as well as the undergraduate students in the Infant Perception and Cognition Laboratory, and the Language and Category Development Laboratory at the University of Iowa for their help with this project. We would also like to thank Prahlad Gupta for input into the design of Experiment 2, Sammy Perone for comments on an earlier draft of this paper, and the parents and children who participated.</p> <ref id="AN0035818660-19"> <title> Footnotes </title> <blist> <bibl id="bib1" idref="ref15" type="bt">1</bibl> <bibtext> We also calculated MRL using the method provided by Mareschal and Tan (2007). The same general pattern was observed.</bibtext> </blist> <blist> <bibl id="bib2" idref="ref18" type="bt">2</bibl> <bibtext> These stimuli were a subset of those used by Ellis and Oakes (2006).</bibtext> </blist> <blist> <bibl id="bib3" idref="ref16" type="bt">3</bibl> <bibtext> In this experiment, as in Experiment 1, we used <emph>productive</emph> vocabulary as an indication of language development. However, Ellis and Oakes (2006) used <emph>receptive</emph> vocabulary with children of the same age and in essentially this same task. Indeed, the mean receptive vocabulary for children in Experiment 2 was 146.41, <emph>SD </emph>= 81.24, <emph>N</emph>= 48, 29–368 words, which is comparable to the receptive vocabulary scores obtained for children during their fourth visit in Ellis and Oakes (2006): 147.57, <emph>SD</emph>= 66.16, <emph>N</emph>= 23, 31–245 words. 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Oakes</p> <p>Reported by Author; Author; Author; Author; Author; Author; Author</p> </aug> <nolink nlid="nl1" bibid="bib12" firstref="ref1"></nolink> <nolink nlid="nl2" bibid="bib11" firstref="ref2"></nolink> <nolink nlid="nl3" bibid="bib19" firstref="ref4"></nolink> <nolink nlid="nl4" bibid="bib26" firstref="ref5"></nolink> <nolink nlid="nl5" bibid="bib20" firstref="ref6"></nolink> <nolink nlid="nl6" bibid="bib21" firstref="ref7"></nolink> <nolink nlid="nl7" bibid="bib16" firstref="ref8"></nolink> <nolink nlid="nl8" bibid="bib24" firstref="ref33"></nolink> <nolink nlid="nl9" bibid="bib31" firstref="ref34"></nolink> <nolink nlid="nl10" bibid="bib14" firstref="ref37"></nolink> <nolink nlid="nl11" bibid="bib25" firstref="ref55"></nolink> <nolink nlid="nl12" bibid="bib10" firstref="ref57"></nolink> <nolink nlid="nl13" bibid="bib15" firstref="ref60"></nolink> <nolink nlid="nl14" bibid="bib18" firstref="ref61"></nolink> <nolink nlid="nl15" bibid="bib13" firstref="ref64"></nolink> <nolink nlid="nl16" bibid="bib17" firstref="ref65"></nolink> <nolink nlid="nl17" bibid="bib22" firstref="ref66"></nolink> <nolink nlid="nl18" bibid="bib23" firstref="ref67"></nolink>
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  Data: Toddlers Can Adaptively Change How They Categorize: Same Objects, Same Session, Two Different Categorical Distinctions
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  Data: <searchLink fieldCode="AR" term="%22Horst%2C+Jessica+S%2E%22">Horst, Jessica S.</searchLink><br /><searchLink fieldCode="AR" term="%22Ellis%2C+Ann+E%2E%22">Ellis, Ann E.</searchLink><br /><searchLink fieldCode="AR" term="%22Samuelson%2C+Larissa+K%2E%22">Samuelson, Larissa K.</searchLink>
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  Data: <searchLink fieldCode="SO" term="%22Developmental+Science%22"><i>Developmental Science</i></searchLink>. Jan 2009 12(1):96-105.
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  Data: Wiley-Blackwell. 350 Main Street, Malden, MA 02148. Tel: 800-835-6770; Tel: 781-388-8598; Fax: 781-388-8232; e-mail: cs-journals@wiley.com; Web site: http://www.wiley.com/WileyCDA/
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  Data: 10
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  Data: 2009
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  Data: Journal Articles<br />Reports - Evaluative
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  Label: Descriptors
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  Data: <searchLink fieldCode="DE" term="%22Toddlers%22">Toddlers</searchLink><br /><searchLink fieldCode="DE" term="%22Classification%22">Classification</searchLink><br /><searchLink fieldCode="DE" term="%22Language+Acquisition%22">Language Acquisition</searchLink><br /><searchLink fieldCode="DE" term="%22Vocabulary+Development%22">Vocabulary Development</searchLink><br /><searchLink fieldCode="DE" term="%22Tactual+Perception%22">Tactual Perception</searchLink><br /><searchLink fieldCode="DE" term="%22Stimuli%22">Stimuli</searchLink><br /><searchLink fieldCode="DE" term="%22Language+Skills%22">Language Skills</searchLink><br /><searchLink fieldCode="DE" term="%22Child+Development%22">Child Development</searchLink>
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  Data: 10.1111/j.1467-7687.2008.00737.x
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  Data: 1363-755X
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Two experiments demonstrate that 14- to 18-month-old toddlers can adaptively change how they categorize a set of objects within a single session, and that this ability is related to vocabulary size. In both experiments, toddlers were presented with a sequential touching task with objects that could be categorized either according to some perceptually salient dimension corresponding to a taxonomic distinction (e.g. animals vs. vehicles) or to some less obvious dimension (e.g. rigid vs. deformable). In each experiment, children with larger productive vocabularies responded to both dimensions, showing evidence of sensitivity to each way of categorizing the items. Children with smaller productive vocabularies attended only to the taxonomically related categorical grouping. These experiments confirm that toddlers can adaptively shift the basis of their categorization and highlight the dynamic interaction between the child and the current task in early categorization.
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  Data: 2009
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  Data: EJ849458
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        PageCount: 10
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      – TitleFull: Toddlers Can Adaptively Change How They Categorize: Same Objects, Same Session, Two Different Categorical Distinctions
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