Children's use of imagery in accessing different types of semantic information

JOURNAL

OF EXPERIMENTAL

Children’s

CHILD

PSYCHOLOGY

28,

404-415 (1979)

Use of Imagery in Accessing Types of Semantic Information

Different

RICHARDS.PRAWAT Michigan State University

AND DEAN KERASOTES Oklahoma State University Semantic retrieval was examined in second graders under an induced imagery and a control condition. Two types of animal properties, perceptual and functional, were presented to children for verification. Properties were high and low in rated association strength: the size of the property (i.e., large vs small) was also manipulated in the case of perceptual meaning. Results suggest that young children rely on imagery in semantic retrieval: however, second graders are also adept at processing functional as well as perceptual meaning, and at using an abstract memory accessing system. Thus, considerable flexibility is evidenced by subjects in semantic retrieval.

In the study described here, the emphasis is on the semantic memory search process in children. One way to examine this process that has proved successful involves an adaptation of the semantic retrieval paradigm used with adults (Smith, Shoben, & Rips, 1974). In this paradigm, reaction times of subjects are measured while they attempt to verify different kinds of subject-predicate statements. Although semantic retrieval research with children is relatively scarce, studies show that the importance of certain dimensions of word meaning does change with development. For example, Prawat and Cancelli (1977) compared retrieval of different types of meaning in kindergarten and third-grade groups; on the basis of their results they argued that functional meaning (i.e., “A lion can bite”) is relatively more accessible than perceptual (“A lion has a mane”) for the younger children, a finding which is consistent with Nelson’s theory (1974). McCauley, Weil, and Sperber (1976) investigated the development of superordinate and associate semantic relationThis study was supported in part by the Research Foundation, Oklahoma State University, Stillwater, OK. Requests for reprints should be sent to Richard S. Prawat, Institute for Research on Teaching, 201 Erickson Hall, Michigan State University, East Lansing, MI 48824. 404 0022~0965/79/060404-12$02.00/O Copyright Q 1979 by Academic Press, Inc. All rights of reproduction in any form reserved

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ships in children’s memory; they found that use of the superordinate, category-type relationship varied with developmental level. One of the most interesting studies was done by Kosslyn (1976b). He recently used the semantic retrieval paradigm to test the hypothesis that younger children (i.e., first graders) use a different type information retrieval system than older children (fourth graders) and adults. Kosslyn (1975, 1976b) maintains that younger children use imagery in accessing semantic information; mental images are generated and are then consulted by children as part of the semantic retrieval process. This is considered to be less efficient than a process used by older children and adults which, presumably, involves retrieving information stored in a nonimaginal, abstract format. If younger children rely on mental imagery in retrieving semantic information, Kosslyn argues, then perceptual characteristics of the property being verified-most notably, size-should be relatively more important than abstract “verbal” characteristics, such as association strength. Kosslyn manipulated these variables to produce two types of animal-property statements: one with properties which were strongly associated with the animal but which were small in perceptual size (“A cat has claws”); the other with properties which were large in size but low in association strength (“A cat has a head”). Subjects were asked to verify the animal-property statements under both control and imagery conditions; in the latter, subjects were asked explicitly to consult a visual image of the animal in making their judgments. Two results from Kosslyn’s (1976b) study are noteworthy. First, in the no-imagery instructions condition, high association/low area properties were more quickly verified than larger, less associated properties, while the opposite effect obtained under the imagery instructions condition. Second, younger children, compared to older, apparently relied more on imagery in memory retrieval regardless of the kind of instructions given. Specifically, Kosslyn found that the first-grade sample tended to evaluate true properties faster in accordance with increasing size under both sets of instructions. However, he warned, these results must be cautiously interpreted in view of the fact that the relevant three-way interaction between property type, age, and instructions failed to reach significance. First graders did report greater use of spontaneous imagery than the fourth graders and the adults. In the present study, an attempt was made to examine Kosslyn’s view that young children use imagery in accessing semantic information. However, some important changes in the procedure used by Kosslyn were made. In Kosslyn’s study subjects were tested in the no-imagery condition followed by the imagery condition. Thus, practice and/or fatigue effects were confounded with the instructional manipulation, a possibility which concerned Kosslyn himself (1976a). In the present study, different subjects were employed in the no-imagery and imagery conditions; also, a

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“stimulus definition” of imagery was used in place of an instructional set definition (Saltz & Finkelstein, 1974). Thus, pictures of animals were used to get children to form perceptual images in the imagery treatment condition. (It should be pointed out that the question of whether or not pictures are stored as mental images is a controversial one (Pylyshyn, 1973). Nevertheless, there is considerable support for a “dual coding” hypothesis (Kosslyn, 1978). Rohwer (1970), for example, presents data which indicate that more imagery is reported by subjects to pictures than to verbal labels representing the pictures. For a recent discussion of this issue, consult Anderson (1978).) In addition to the property variables examined by Kosslyn (i.e., association strength and size), the effect of type of meaning on retrieval was also examined in this study. The ability to retrieve perceptual properties of animals was compared with functional properties (“A cat can scratch”) imagery condition. under two conditions: a control and an “induced” Previous research (Saltz & Finkelstein, 1974) suggests that the use of imagery facilitates the learning (and retrieval) of perceptual concepts but not of functional concepts. Thus, one might expect the use of animal pictures to exert a differential effect on subjects when verifying the two types of animal-property statements (i.e., perceptual and functional). Accordingly, high and low saliency, perceptual and functional property statements were presented to subjects for verification under the two conditions; saliency and property size were simultaneously manipulated only for the perceptual property statements. While saliency remains a relevant variable when functional properties are being verified, it was thought, size of the attribute does not. On the basis of previous studies by Kosslyn (1976b) and Saltz and Finkelstein (1974), the following outcomes were predicted: (1) It was thought that second-grade subjects in the induced imagery condition would take significantly less time to verify statements than those in the no-imagery control. The reasoning behind this prediction is as follows: Saltz and Finkelstein (1974) found that induced imagery of the sort used in this study facilitates the learning of perceptual concepts. If Kosslyn is correct, and young children process by means of imagery regardless of instructions, then children in the Saltz and Finkelstein study were presumably using their own images in the no-imagery control condition; these were either insufficiently vivid or in some other way inadequate to produce the quality of processing found in the induced imagery children. From this it appears to follow that induced imagery is more effective than spontaneous imagery, and therefore should lead to faster processing. (This interpretation of previous results runs counter to Kosslyn’s (1976b) belief that younger children’s spontaneous imagery is as effective as induced imagery in retrieving semantic information.) (2) If young children rely on the use of imagery in retrieving semantic information, then percep-

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tual meaning should be retrieved more quickly than functional because this kind of information more readily lends itself to imaginal representation. Thus, we predicted a significant property type effect, with perceptual meaning being more accessible than functional meaning. (3) Type of meaning and saliency should significantly interact: Perceptual properties that are low in saliency but large in size should be retrieved more quickly than those that are high in saliency but smaller in size; functional properties that are highly salient, on the other hand, should be retrieved faster than those that are not. (4) Finally, we might assume that this two-way interaction will be much stronger in the imagery group, resulting in a significant three-way interaction between treatment condition, property type, and saliency. METHOD Materials

Forty-eight noun-property statements were presented to subjects by tape recorder. Twenty-eight of the statements were true and 20 were false. Statements were constructed in two stages: First, production frequency data were obtained from a sample of adults (N = 30) by having them complete statements relating to animals by supplying perceptual or functional kinds of properties (i.e., “A cat has . . .” or “A cat can . . . “). From these data, 56 properties-28 perceptual and 28 functional-were selected for rating by a sample (N = 35) of second and third graders. The rating scheme was identical to one used in a previous study (Prawat & Cancelli, 1977). Briefly, children were asked to pretend that they were telling a friend about an animal that the friend knew nothing about. Properties were rated on a 1 to 5 scale according to whether it was something that they would have thought of “first” (l), “a little later” (3), or that “they would not have thought of’ in telling their friend about the animal (5). In order to check the validity of these ratings a correlation was computed between the children’s saliency ratings and adult production frequency scores. This correlation was quite high (.72); also, the original set of perceptual properties were rated on a 1 to 5 scale by 10 adult judges who were asked to “image the whole animal” and then rate each property according to its relative size on the animal. A score of 1 was said to apply to a high area property like “skin,” while a score of 5 was to be used for a barely perceivable attribute like “teeth.” The correlation between these ratings and the saliency ratings by the second- and thirdgrade sample was .03. These results, as well as Kosslyn’s, indicate that “even if children have a ‘mental picture’ before their ‘mind’s eye’ when making association ratings from memory, their ratings will not be determined by predominancy of the property on this picture” (1976b, p. 436).

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The final list of 48 noun-property statements used in the study was constructed from these rated properties according to the following criteria: First, the high and low “saliency” items differed significantly in rated association strength: ratings for the two type items did not differ across the perceptual/functional property distinction. The mean rating for the seven high-saliency, perceptual properties was 2.15, and for the highsaliency, functional properties, 2.07. The ratings for the low-saliency, perceptual and functional items were 3.25 and 3.12, respectively. Second, high association items in the perceptual category, following Kosslyn (1976b), were low in area; the low association items, on the other hand, were high in area. Examples of sentences differing in property type (i.e., perceptual vs functional) and saliency are provided in Table 1. Because of the obvious difficulties involved in assessing the “size” of those aspects of an image that depict a functional relation, no effort was made to manipulate this variable along with the saliency variable, as was done with perceptual properties. False perceptual and functional type statements were constructed by randomly selecting properties used in the rating task which were not used in constructing true statements. An equal number (IO) of perceptual and functional properties was selected. The order of the 48 animal-property pairs used in sentences was randomized, except that no animal or property was probed twice within three trials. Sentences were recorded with a 3-set pause within sentences, between the verb and the property word, and a IO-set pause between sentences. TABLE EXAMPLES

OF SENTENCES

VARYING

1 IN PROPERTY

TYPE

AND

Perceptual High saliency/small size

Low saliency/large size

A A A A A

A A A A A

dog has a tail. cat has whiskers. monkey has hands. bird has a beak. horse has hoofs.

dog has a body. cat has legs. monkey has skin. bird has a head. horse has a back.

Functional High saliency

Low saliency

A A A A A

A A A A A

dog can bite. cat can scratch. monkey can swing. bird can fly. horse can run.

dog can sit. cat can drink. monkey can grab. bird can chirp. horse can snort.

Note: Property size is not relevant for functional-type

properties.

SALIENCY

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Black and white drawings of animals were used in making slides. The line drawings were selected by the two experimenters from children’s books on the basis of their “typicality” as examples of the relevant animals. Where considerable “species” variability was observed across drawings-that is, in the case of the “bird,” “dog,” and “bug” categories-previous research was consulted to select the most typical instance (Battig & Montague, 1969; Smith et al., 1974). As a result, the following examples were selected for each of the categories: a “collie,” a “robin-sparrow” type of instance, and a “dragonfly.” The latter was not the most typical example of the bug category but it did have all the desired attributes (i.e., the high and low saliency properties). There was less variability across drawings for the “cat,” “horse,” “turtle,” and “monkey” categories. Pilot data revealed that children had no difficulty supplying the correct category names for the animal pictures used in the study. The line drawings were made into 5 x 5-cm slides. Animal images on the slides were of nearly identical size. Thus, four of the images were 3 cm in length and 1.5 cm in height; three were exactly 2 x 2 cm in size. The slides were presented at a 1-set rate by means of a Lafayette 41010 automatic projection tachistoscope to subjects in the image condition. Slides were projected onto a screen immediately following presentation of subject nouns in the subject-predicate statements. Subjects in the imagery condition were instructed to attend to the “pictures” and to use them to help remember what the animals look like. Procedure Test sentences were presented by tape recorder. Subjects had been instructed to listen carefully to each sentence and to decide as quickly as possible if what was said about the animal was right or wrong. Subjects responded “yes” if the statement was right and “no” if it was wrong. Several practice trials preceded the experiment to insure that subjects understood instructions. A Lafayette 63010 reaction timer was activated by the experimenter upon presentation of the final word of each sentence, with the experimenter releasing an initiate switch on the control unit; the timer was terminated when the experimenter pressed a telegraph key upon hearing the subject’s response. Responses of subjects were recorded along with reaction times to the nearest hundredth of a second. The experimenter was unaware of the hypotheses being tested. Half the subjects (IV = 15) were randomly assigned to the no-imagery condition and half to the imagery condition. Only subjects in the imagery condition were shown the slides; subjects in the other condition heard the sentences presented aurally, without visual accompaniment. Subjects A total of 30 subjects were randomly selected from a second-grade classroom in a predominantly middle-class elementary school. The mean

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age of subjects was 7 years 6 months (range = 7 years 0 months to 8 years 0 months). Subjects were English speaking and had no known perceptual problems. Children were in the above average ability range as measured by performance on the Stanford Achievement Test. Equal numbers of males and females were included in the two groups (i.e., no-imagery and imagery). It had been decided to include only children with error rates less than 20% on the sentence verification task in the experiment. However, none of the subjects in this study needed to be excluded because of excess error rates. RESULTS

Mean reaction times for each subject when verifying each type of true sentence constituted the dependent variable in this study. These were computed to the nearest hundredth of a second and were obtained by averaging reaction times for each subject for each of the four propertytype by saliency cells. Thus, the response latencies of each subject for each type of sentence (i.e., high saliency, perceptual) were averaged to determine a mean reaction time. In the study, there were 7 true sentences of each type, for a total of 28 true sentences. Table 2 presents sentencetype means for subjects in the imagery and no-imagery conditions. Only correct responses were analyzed. Also, response latencies greater than 5 set were treated as nonresponses. Only 2% of the total responses of the second-grade subjects fell into this category. Since interest in this study centered on how semantic information was accessed and retrieved from memory, only the “true” sentence verification times were analyzed. It is not certain what false responses tell us, if anything, about this process (Kosslyn, 1976a, 1976b). Because preliminary inspection of the data revealed no appreciable sex differences for the animal-property statements, data were combined for males and females in the subsequent analyses. Three independent variables were examined in the study: a treatment factor (no-imagery and imagery), a property type factor (perceptual and TABLE MEAN

REACTION

TIMES

FOR SUBJECTS

2

BY GROUP,

PROPERTY

Imagery group Perceptual

Functional

TYPE,

AND

SALIENCY

No-imagery group

High saliency/ small size Low saliency/ large size

121”

107

122

101

High saliency Low saliency

123 134

110 117

n In hundredths of a second.

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functional meaning), and a saliency factor (high and low). As indicated above, high and low saliency perceptual statements were constructed so as to allow us to test the effects of an additional, independent variableproperty size. Thus, perceptual properties of animals high in saliency, but small in size (i.e., tail, beak, whiskers), and low in saliency but large in size (i.e., body, skin, back) were examined. The experimental design consisted of a 2 (Treatment) x 2 (Property Type) x 2 (Saliency) factorial, the last two factors being repeated measures in the overall analysis of variance. In this analysis, only one of the three main effects was significant. This was the property type effect, F (1, 28) = 4.86, p < .03. As expected, perceptual properties were more quickly retrieved than functional properties. This finding appears to support Kosslyn’s view that young children use mental imagery in accessing information in memory. However, this conclusion must be qualified because, contrary to our earlier prediction, subjects in the induced imagery condition did not retrieve semantic information more quickly than those in the no-imagery control condition, F (1, 28) = 1.35, p < .25. From this, we might conclude one of two things: Either subjects are unable to make effective use of induced imagery in the task employed here, or, as Kosslyn (1976b) maintains, subjects in the no-imagery control condition make effective use of their own spontaneous imagery when retrieving information. In order to examine this issue further, two directly relevant a priori tests were conducted. In the first, the retrievability of perceptual items was compared for subjects under imagery and no-imagery conditions. In the second, the retrievability of large-sized perceptual attributes was contrasted with that of small-sized perceptual attributes. If the first comparison is significant-with imagery subjects able to retrieve information faster than no-imagery subjectswhile the second comparison is not significant, the evidence is contrary to the spontaneous imagery interpretation; if, on the other hand, the size comparison is significant and the group is not, the evidence is strong for spontaneous imagery; if both are significant, it suggests that some spontaneous imagery occurs, but that it is weak: if neither is significant, it suggests that Kosslyn may be incorrect in assuming that imagery is relevant to this type of task. In fact, the first planned contrast between groups was significant, t (28) = 3.44, p < .Ol: however, those in the induced imagery condition took significantly lor-rger to evaluate perceptual properties than those in the no-imagery control. Meanwhile, the comparison of large vs small percepts did not approach significance, t (28) = .46, p > .05. This result was unforeseen. Fortunately, an examination of means in Table 2 suggests yet another possibility. As can be seen, in the no-imagery condition large-sized perceptual attributes were retrieved more quickly than small-sized attributes, although this difference is not significant, r (15) = .87, p > .05. Virtually no property-size differences

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exist in the imagery condition. It may be, then, that the images provided to subjects actively interfered with the subjects’ own spontaneously generated imagery. In the analysis of variance, the saliency effect was not significant, F (1, 28) = 1.35, p < .25. The predicted two-way interaction between property-type and saliency was significant, however, F (1,28) = 4.25,~ < .05. It was thought that this interaction would reflect the fact that property size is an important factor in retrieving perceptual meaning, while association strength is important in retrieving functional meaning. The interaction that was obtained is shown in Fig. 1. As Fig. 1 shows, only the second part of this hypothesis was supported. Thus, the high-saliency, functional items were retrieved more quickly than the low (p < .05). The saliency factor played a key role in retrieving functional meaning. Also, as was indicated, it took children significantly longer to retrieve functional compared to perceptual meaning, which suggests that different processes may have been involved. These two findings provide support for Saltz and Finkelstein’s (1974) conclusion that functional meaning does not readily lend itself to an imaginal format. However, it should be pointed out that inducing imagery also had a negative effect on the process of retrieving functional meaning. Subjects’ error rates for the different conditions were correlated with their reaction times in order to determine if there was a speed-accuracy traderoff. As Kosslyn (1976b) points out, if error rates increase as reaction times decrease, the data may simply reflect differences in children’s willingness to guess rather than real differences in memory retrievability. REACTION TIME &c.)

c

1.25 1.20 -

1.15 1.10 1.05 i 1 .oo t 1, 1 PERCEPTUAL MEANING

1 FUNCTIONAL MEANING

FIG. 1. Reaction times for sentences high and low saliency as a function of property type.

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The correlation between errors and reaction times was -.07, thus there was no speed-accuracy trade-off. Error rates in percentages for subjects under property-type and saliency conditions are presented in Table 3. DISCUSSION

Overall, the findings of this study provide some support for Kosslyn’s (1976b) conclusion that young children rely on imagery in retrieving semantic information. However, it also looks as if the semantic retrieval process of the second grader is sensitive to “abstract” characteristics of word meaning such as association strength; a representational format which makes use of these characteristics can be an efficient way for the child at this age to access certain kinds of information-specifically, “functional” as opposed to “perceptual” meaning. Two of the four hypotheses tested in this study were supported. One hypothesis which was not supported predicted that imagery group subjects would take less time to verify statements than control group subjects. This hypothesis was based on two assumptions: first, that the use of imagery in fact facilitates semantic retrieval; second, that induced imagery is more effective than spontaneous imagery. However, a direct comparison of subjects’ response latencies under the two conditions reveals that relatively more time was spent retrieving perceptual properties when imagery was induced than when it was not. This finding, combined with the fact that subjects in the no-imagery control appear to be responsive to the perceptual size of atttibutes, suggests that induced imagery may actually interfere with the child’s own spontaneously generated imagery. Clearly, this interpretation is speculative, but it is consistent with the pattern of results which was obtained. In this study, we predicted, and obtained, a significant two-way interaction between property-type and saliency. Our expectation was that low saliency, large perceptual attributes would be retrieved more quickly than high saliency, small attributes; high saliency functional attributes were expected to be more accessible than low saliency attributes. Only the second part of this two-part hypothesis was confirmed. However, this finding, in and of itself, does not represent a severe blow to Kosslyn’s thesis. In fact, in Kosslyn’s study, the first-grade sample was equally TABLE ERROR

Perceptual Functional

RATES

3

IN PERCENTAGES FOR SUBJECTS AS A FUNCTION PROPERTY TYPE AND SALIENCY

OF

High saliency/small size (%)

Low saliency/large size (%I

4 II

11 10

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affected by the saliency and property size factors under the no-imagery condition. He concluded, “The fact that first graders, unlike older people, did not generally respond more quickly to highly associated ‘true’ items is of interest in its own right. This finding suggests that memory processes and/or structures do change in qualitative ways with age” (1976b, p. 443). In this study, functional meaning took significantly longer for second graders to access than perceptual meaning. In the context of the other expected outcomes, it was thought that this result would lend further support to Kosslyn’s imagery hypothesis. Perceptual meaning, the argument goes, can be retrieved more quickly than functional meaning because it more readily lends itself to an imaginal format. Although this interpretation still appears valid, it is weakened somewhat by other results obtained in the study. For example, it is difficult to reconcile this notion with the fact that the presentation of images interferes with the accessing of functional as well as perceptual meaning. On the other hand, the retrieval of functional meaning is strongly influenced by an “abstract” dimension of word meaning, namely, saliency. Clearly, a great deal of additional research must be done before we can hope to adequately understand this process in children. However, it does appear that Kosslyn’s (1976b) views regarding the importance of imagery in the process are correct, as far as they go. The problem is that they fail to take into account the young child’s flexibility in such a task. Thus, second graders show a remarkable ability to process different types of meaning (functional as well as perceptual), and to employ different memory accessing systems (abstract as well as imaginal). REFERENCES Anderson, J. R. Arguments concerning representations Review.

1978,

for mental imagery. Psychological

85, 249-277.

Battig, W. F., & Montague, W. E. Category norms for verbal items in 56 categories: A replication and extension of the Connecticut Category Norms. Journal ofExperimental Psychology Monograph, 1969, 80 (3, Pt. 2). Kosslyn, S. M. Information representation in visual images. Cognitive Psychology, 1975,7, 341-370. Kosslyn, S. M. Can imagery be distinguished from other forms of internal representation? Evidence from studies of information retrieval times. Memory & Cognition, 1976, 4, 291-297. (a) Kosslyn, S. M. Using imagery to retrieve semantic information: A developmental study. Child Development. 1976, 47, 434-444. (b) Kosslyn, S. M. Measuring the visual angle of the mind’s eye. Cognitive Psychology, 1978, 10, 356-389. McCauley, C., Weil, D., & Sperber, R. The development of memory structure as reflected by semantic-priming effects. Journal of Experimental Child Psychology, 1976, 22, 511-518. Nelson, K. Concept, word, and sentence: Interrelations in acquisition and development. Psychological Review, 1974, 81, 267-285.

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Prawat, R. S., & Cancelli, A. A. Semantic retrieval in young children as a function of type of meaning. Developmental Psychology, 1911, 13, 354-358. Pylyshyn, Z. W. What the mind’s eye tells the mind’s brain: A critique of mental imagery. Psychological Bulletin, 1973, 80, l-24. Rohwer, W. D., Jr. Images and pictures in children’s learning: Research results and instructional implications. In H. W. Reese (Chair) Imagery in children’s learning: A symposium.

Psychological

Bulletin,

1970,

73, 393-403.

Saltz, E., & Finkelstein, C. Does imagery retard conceptual behavior? Child Deve/opment. 1974, 45, 1093-1097. . Smith, E. E., Shoben, E. J., & Rips, L. J. Structure and process in semantic memory: A featural model for semantic decisions. Psychological Review, 1974, 84, 214-241. RECEIVED: November

17, 1977;

REVISED:

November

15, 1978.