Knowledge base influences on judgments of frequency of occurrence

Cognitive

Development,

$223-233

Knowledge

(1990)

Base Influences on judgments of Frequency of Occurrence Joanna

University

of Oklahoma

and

University

of Science

& Arts

F. Harris of Oklahoma

Francis T. Durso Nancy 1. Mergler Susan K. Jones University

of Oklahoma

Chi and others have shown that a subject’s knowledge base can have dramatic effects on cognitive tasks, sometimes reversing typical developmental differences. On the other hand, judgments of frequency-of-occurrence information have been shown to be immune to factors that typically affect memory. Kindergartners and adults judged frequency of well-known or unknown stimuli. Children were better able to judge frequency of occurrence of classmates than of famous adults (Experiment 1) or unknown children (Experiment 2). Similarly, adults were better able to judge frequency of occurrence of known adult faces than of unknown children (Experiment 1) or unknown adults (Experiment 3). The experiments reported here indicated that even an elementary process like frequency estimation is influenced by domain-specific knowledge of the stimuli.

In recent years, there has been increasing interest in the role ‘that an acquired knowledge base plays in encoding strategies, memory organization, and retrieval of information. The original interest in this area emerged in the cognitive literature, where researchers demonstrated that differences existed in the way in which experts and novices organized and recalled information (e.g. Chase & Simon, 1973). This research was supported in part by a grant from the Associates Fund for Research, University of Oklahoma, to J.F. Harris & F.T. Durso. Portions of this research were presented at the Biennial Meeting of the Society for Research in Child Development, 1989, Kansas City, Missouri. The authors thank Richard Reardon, Jack Kanak, Sue McPherson, and Larry Toothaker for their constructive comments on earlier drafts of this paper, and Susan McCurdy for her dedicated assistance in data collection. Finally, special thanks to the teachers, parents, and children of Middle Earth Day Care Center, Norman, Oklahoma for their cooperation and patience during data collection. Correspondence and requests for reprints should be sent to Joanna F. Harris, Department of Psychology, University of Oklahoma, Norman, OK 73019. Manuscript

received

July 7, 1989;

revision

accepted

November

10, 1989

223

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F. Harris,

Francis

T. Durso,

Nancy

1. Mergler,

and Susan

K. Jones

Developmental psychologists have also begun to explore the impact that knowledge base has on children’s memory performance (Bjorklund, 1987, 1988; Chi, 1977, 1978, 1985; Chi & Ceci, 1987; Lindberg, 1980; Omstein & Naus, 1985). Since Chi (1977) first eliminated developmental differences in recall and then reversed traditional developmental differences (Chi, 1978), a number of empirical findings have accrued that support the idea that knowledge base is an important variable in the performance of various cognitive tasks. The tasks typically used, whether performed by children or adults, have required conscious deliberation. There are, however, a number of cognitive tasks that are not as deliberate and that appear to operate without influence from a number of typically powerful variables. The goal of the experiments in this article was to detemnne the benefit of knowledge base on a simple memory task that cognitive psychologists believe requires little or no conscious effort. Hasher and Zacks (1979, 1984) have proposed that frequency of occurrence is encoded automatically in memory, and thus the judging of frequency should be unaffected by the age, ability, education, or motivation of the individual. In fact, a number of studies lend credibility to this proposal: Children of kindergarten age seem just as able as older children and adults are to judge frequency-of-occurrence information for a variety of concepts (Ellis, Palmer, & Reeves, 1988; Goldstein, Hasher & Stein, 1983; Hasher & Chromiak, 1977, Experiment 1; Hasher & Zacks, 1979, Experiment 1; Johnson, Raye, Hasher & Chromiak, 1979; cf. Ghatala & Levin, 1973; Lund, Hall, Wilson, & Humphreys, 1983). A review of the literature led Hasher and Zacks to state that “the major conclusion of this area of research stands on a firm empirical base: The encoding of frequency information is uninfluenced by most task and individual difference variables. As a result memory for frequency shows a level of invariance that is highly unusual in memory research.” (Hasher & Zacks, 1984, p. 1385). Developmental studies of frequency judgments thus far have, quite naturally, used materials familiar to children (e.g., Hasher & Zacks, 1979). Studies with adults have investigated the interaction of familiarity and frequency, but no clear pattern has emerged. Rao (1983) found that subjects were less accurate when judging words of high linguistic frequency compared to those of low linguistic frequency. On the other hand, Fidler, Zechmeister, and Shaughnessy (1988) reported that college students were more accurate at judging frequency of popular songs compared to those which they could not identify. The experiments of this article explore the effect that an acquired knowledge base has on children’s assessment of frequency-of-occurrence information, by comparing judgments of stimuli chosen from a well-known set of persons (e.g., classmates) to judgments of stimuli chosen from an unknown set of persons. The null hypothesis for these experiments follows Hasher and Zacks (1979, 1984) and states that, regardless of the age and knowledge level of the subjects, there will be no difference in the assessment of frequency-of-occurrence information.

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and Frequency

EXPERIMENT

1

The first experiment included both children and adults. Each group was shown known (i.e., classmates for children and famous people for the adults) and unknown faces at different frequencies. Subjects were then asked, during a forced-choice task, to select the person they had seen more often. Methods Subjects. Subjects were 18 adults and eighteen 5year-olds. The adults were introductory psychology students from the University of Oklahoma who participated in partial fulfillment of a research familiarization requirement. The children were kindergartners from a Norman area preschool. All children were members of the same class and were tested in the middle of the academic year (February). Materials. Materials were faces of famous adults and faces of the children’s classmates. The faces of famous people were chosen based on a norming study in which 120 introductory psychology students attempted to identify the faces; these judges were shown 100 faces. In the study, 50 of the faces were celebrities frequently seen in the media (political figures, actors) and 50 of the faces were individuals who had been featured in connection with human interest stories (e.g., a school superintendent, an accountant). Subjects were asked to indicate if they recognized the face by checking “yes” or “no. ” !f they recognized the face, they were then asked to identify the face by name or to give one or two facts about the person. For example, the subject might identify “Don Johnson” by name or as an “actor from Miami Vice. ” During the scoring process, names were given 2 points and facts were given 1 point. Faces that had not been recognized were given a zero. For the current experiment, the 18 most recognized faces that we hypothesized would not be known to children were used as the stimuli. The faces of children’s classmates were simply the faces of the 18 children who participated in the experiment. In addition, one other classmate’s face was used to replace the face of the child who was the subject. Study Phase. Photocopies were made of each picture of a famous person and each photograph of a child. Individual photocopies were then placed on 3” x 5” index cards. Eighteen packets of cards were prepared. Each packet contained 18 famous faces and 18 children’s faces; with each type of face, one-third were presented once, one-third twice, and one-third four times for a total of 84 cards. A child’s packet did not include a photocopy of himself or herself. Instead, the additional child’s face was substituted. Assignment of faces to levels of frequency was counterbalanced such that, across subjects, by the end of the experiment each face was seen in each frequen-

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F. Harris,

Francis

T. Durso,

Nancy

L. Mergler,

and Susan

K. Jones

cy condition by an equal number of subjects. One adult and one child saw the materials from each packet. Order was randomized for each packet. Test Phase. The frequencies of occurrence in the study phase (1, 2, and 4) allowed faces to be paired so that the difference in frequency between members could be either 1 (2 - l), 2 (4 - 2), or 3 (4 - 1) occurrences. In addition, the pairs were of children paired with children (C-C) or famous faces paired with famous faces (F-F). We also included mixed stimuli (C-F) to study any bias children or adults might have that may affect frequency judgments in less controlled circumstances. Each subject made judgments for each combination of frequency difference and pair composition. For all test phase conditions, the paired faces were prepared as described previously and each pair was placed on a 3” X 5” index card, with the faces side by side. Again, 18 packets were made, and counterbalancing across subjects ensured that every face would be placed with every other face equally often by the end of the experiment. One child and one adult saw each set of test stimuli. Order of the test stimuli was again randomized for each packet.

Procedure Subjects were tested individually. The adults were tested in a laboratory on campus; the children were tested in the library of the preschool. A female experimenter approached each child in the classroom and asked if he or she would like to play a game with the experimenter. All agreed to play the game. Children were then excused from class and accompanied the experimenter to the library, where the child sat down at a table opposite the experimenter. Study Phase. Both adults and children were told that the experimenter wanted to know what faces the subjects recognized. They were told to respond “yes” if they recognized the face and “no” if they did not. The 84 stimuli were presented one at a time at a 3 s rate. The experimenter marked “yes” or “no” on a checksheet for each response that the subject made. After all cards were shown there was a 3 minute rest period before the test phase began. Test Phase. The subjects were told that they would now be shown 18 cards, each containing two faces. Their task was simply to point to the face they remembered having seen more often during the first phase of the experiment. Finally, as a manipulation check, subjects were asked to look at the 36 faces and to identify by name the people they recognized.

Results The manipulation check confirmed that the children knew their classmates and did not know the famous people. Similarly, the adults recognized the famous

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people and did not know the children. In the analyses, all significant results were at an alpha level of .05 or less unless otherwise indicated. A 2 X 2 X 3, Knowledge (C-C vs. F-F) X Age (children, adults) X Frequency Difference (1, 2, 3) analysis of variance (ANOVA) was conducted for the percentage of correct responses for the two “pure” conditions (C-C and F-F). The results of this analysis revealed 1 two-way interaction and one main effect. The interaction of age and knowledge, F( 1, 34) = 6.08, indicated that children did better when they were asked to make frequency judgments about classmates than when asked to make frequency judgments about famous adults. In fact, when judging the frequency of adult faces, the children operated at chance (50%) but were reliably above chance, t( 17) = 2.39, when judging their classmates (61%). Similarly, adults tended to do better with materials known to them than with the children’s faces. However, we did not find in our data a reversal of traditional developmental patterns: In all cases the adults, even when judging unknown stimuli, did better than the children. The one main effect was for frequency difference, F(2.68) = 3.14: It was easiest for everyone to select the correct answer when the choice was being made between faces seen 1 versus 4 times (78%). The selection was more difficult and more inaccurate when the choice was being made between faces seen 1 versus 2 times (66%) or 2 versus 4 times (66%). We also conducted a similar analysis on the C-F condition in which subjects were asked to judge between a child and a famous adult. Although the C-C and F-F conditions did not allow a knowledge-base bias to operate, we were interested in detemrining the extent to which such a bias might operate in less controlled situations. A two-way interaction of Knowledge X Age, F( 1,34) = 7.37, indicated a propensity on the part of the children to choose the more known of two stimuli (see Table 2). Within the scope of the experiment, children picked classmates over unknown faces, regardless of presentation frequency in the experiment. The fact that children are better judges of frequency of occurrence for their classmates than for famous adults suggests that knowledge base can influence relatively elementary memory processes. In fact, the children’s chance perforTable 1. Percentage Correct of Six Opportunities for Both Ages for the Two Pure Conditions of Experiment 1 Stimuli Children

Age

Children Adults

61 82

Adults 50 90

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F. Harris,

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T. Durso,

Nancy

1. Mergler,

and Susan

K. Jones

Table 2. Percentage of Three Opportunities on which a Child was Chosen as More Frequent as Function of the Correct Choice and Age of the Subject (Experiment 1) Stimuli Choosing Children when They are Incorrect

Choosing Children when They are Correct Age

Children Adults

73 83

71 21

mance in judging adult faces implies that frequency information about the unknown stimuli was simply not available in a form that allowed discrimination among the various adults. However, because the stimuli were classmates versus adults, it is unclear how domain-specific the knowledge base must be. It is possible that children are more adroit at discriminating among members of the general class of children’s faces than they are among adult faces, and thus the effect observed here would not imply a richly interconnected set of concepts that had been acquired by repeated and varied experience. Experiment 2 was designed to see if children are better at judging frequency of their classmates than of unknown children, and Experiment 3 was designed to test the analogous hypothesis for adults. EXPERIMENT

2

Methods Subjects. Subjects were twelve 5-year-olds from a Norman area preschool. As in Experiment 1, all were members of an intact kindergarten classroom and were tested in the middle of the academic year (January). None had participated in Experiment 1. Materials and Procedure. Materials were 12 faces of children from the subjects’ classroom and 12 faces of children from another kindergarten in a different preschool. In addition, two children’s faces from the classroom, one girl and one boy, substituted for the faces of the boy and girl subjects, respectively. With the reduction in the total number of faces, from 36 in Experiment 1 to 24 in Experiment 2, each study packet constructed contained 56 faces. The test packet included only pairings of faces from the same category: Known children were paired with known children (K-K) and unknown children were paired with unknown children (U-U). All pairings were of same gender children. Other than these changes, the construction of the materials and the procedure were the same as in Experiment 1.

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Results Fifteen children, 7 males and 8 females, participated in the experiment, but only data for 12 children were analyzed. Data from 3 children were excluded because they did not know the children in their classroom. After making inquiries, we found that two boys and one girl were new to the classroom, and although children in the classroom knew them, the manipulation check indicated that they only knew some of their classmates. A two-way ANOVA revealed that the children did better when they were judging classmates than when they were judging pictures of unknown children, F( 1,ll) = 7.30. The subjects were more accurate (86%) when judging how often they had seen their classmates compared to how often they had seen unknown children (65%). This study indicated that children do perform better when they are knowledgeable of the data base that they are asked to judge. It is also noteworthy that children were able to judge frequency at better than chance levels even when the stimuli were unfamiliar to them, t(l1) = 2.42, as long as the general category (i.e., children’s faces) was a well-used one. Thus, the chance performance observed in Experiment 1 may occur only when the stimuli are very unfamiliar; in such a case, frequency information may not accumulate in a way that allows subjects to use the nominal stimulus to retrieve frequency information. Nevertheless, the findings of Experiment 2 indicate that domain-specific knowledge contributes above and beyond any general familiarity with the stimulus class.

EXPERIMENT

3

Methods Subjects. Subjects were 9 senior psychology students from the University of Sciences and Arts of Oklahoma (USAO). As in Experiment 2, subjects were members of an intact classroom (enrollment of 15) and were tested near the end of the semester (early April); this class was exclusively female. None had participated in Experiment 1. Materials and Procedure. Materials were 12 faces of students from the subjects’ classroom at USA0 and 12 faces of adult females from the University of Oklahoma. The USA0 faces were those identified as the most well-known classmates, based on a 5-point Likert scale. On the average, the students whose faces were used as stimuli were judged by classmates as a person with whom “I have had three or more classes and consider a friend but interaction with this person has been limited to the classroom. ” The unknown faces were of conveniently chosen females not associated with USA0 and were approximately the same age as the USA0 students. The test packet included only pairings of faces from the same category: Known adults were paired with known adults (K-K) and unknown adults were paired with unknown adults (U-U). Other than these

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F. Harris,

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T. Durso,

Nancy

1. Mergler,

and Susan

K. Jones

changes, the construction of the materials and the procedure were the same as in Experiment 2. Results A two-way ANOVA revealed that the college students did better when they were judging their classmates (96%) than when they were judging pictures of unknown adults (85%), F( 1,8) = 8.00. Thus, even adults performed better when they judged stimuli belonging to an acquired knowledge base. There was also a main effect for frequency category, F(2,16) = 5.58. Adults scored perfectly (100%) when selecting between faces seen 1 versus 4 times. The selection was more inaccurate when the choice was being made between faces seen 1 versus 2 times (80%) or 2 versus 4 times (92%). GENERAL

DISCUSSION

In Experiment 1, children and adults were asked to make frequency-of-occurrence judgments about the children’s classmates and famous adults. We found that children did better when they were asked to make judgments about children who were classmates than when they were asked to make judgments about famous adults. In fact, when judging frequency of occurrence for adult faces, the children performed at chance. In addition, adults did better when they were asked to make judgments about famous adult faces than when they were asked to make judgments about children’s faces. However, we did not find in our data a reversal of traditional developmental patterns (see Chi, 1978; Lindberg, 1980); in all cases adults, even when judging the children’s classmates, performed better than the children. In Experiment 2, children were asked to make judgments about children who were their classmates and judgments about kindergarten children they did not know. The experiment replicated our findings in Experiment 1: Children were better at making frequency-of-occurrence decisions about their classmates than they were at making frequency-of-occurrence decisions about unknown faces, indicating that the effect involves domain-specific knowledge. However, comparing across experiments, children were better at judging unknown children than unknown adults, suggesting that membership in an often used, though broader domain, also influenced judgments. In Experiment 3, adults were asked to make frequency-of-occurrence decisions either about unknown adult faces or known adult faces. Once again, adults performed better in making frequency-of-occurrence decisions about known faces than in making frequency-of-occurrence decisions about unknown faces. We have supported the notion that the benefits of knowledge base are seen in even the most simple of memory tasks. Children and adults perform better when they are asked to make frequency-of-occurrence judgments about stimuli from an established knowledge base, in the children’s case, photographs of their class-

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mates. However, knowledge base was insufficient to make children’s performance comparable to that of the adults. Regarding frequency judgments, we now have evidence that frequency of occurrence is not as immune to other factors as might have been expected; we are not, however, the first to find data contrary to this contention (e.g., Fidler, et al., 1988; Fisk & Schneider, 1984; Ghatala & Levin, 1973; Greene, 1986; Hanson & Hirst, 1988; Kausler, Lichty, & Hakami, 1984; Lund et al., 1983; Sanders, Zembar, Liddle, Gonzalez, & Wise, 1989; Williams & Durso, 1986). The preceding is not to suggest that we dispute the notion that information that can be used to judge frequency is registered in memory. Clearly, children must register prior experience with even unknown stimuli in order to build any type of knowledge base. We believe that the differences we and others have found have little to do with the encoding of frequency information in this sense. Bjorklund and Bjorklund (1985) suggest three ways in which a knowledge base might affect subsequent memory. All three ways emphasize the role of retrieval in memory processes; in the frequency literature, the Bjorklund and Bjorklund proposals would be viewed as consistent with the availability heuristic (TVersky & Kahneman, 1973; Williams & Durso, 1986). For Bjorklund and Bjorklund, strategic organization and automatic organization are both ways in which the interconnections among members of a knowledge base can enhance recall. Subjects might deliberately or unintentionally use the relations among concepts to aid retrieval. The third influence of a knowledge base is a more itemspecific one. The knowledge base allows the child to encode information about a classmate more elaborately than information about unknown persons. In this view, fewer features of the unknown children and unknown adults are encoded compared to those of the known classmates. Later, when judging frequency, the child is less able to retrieve the individual occurrences, and judges frequency less accurately; to a child, the unknown persons are simply less distinguishable and thus judgments of frequency for a particular face are difficult (orimpossible if the faces are of adults). Although organization obviously affects recall in a number of ways, its effect on recognition is less apparent (e.g., Kintsch, 1968), and presumably organization would affect frequency judgments to an even lesser extent. Item-specific information, on the other hand, has been implicated in recognition as well as in recall (e.g., Durso & O’Sullivan, 1983; Hunt & Mitchell, 1982), and we believe that the frequency effects observed here are, at least in part, due to such effects. REFERENCES Bjorkhmd, D.F. (1987). How age changes in knowledge base contribute to the development of children’s memory: An interpretive review. Developmental Review, 7. 93-103. Bjorklund, D.F. (1988). Acquiring a mnemonic: Age and category knowledge effects. Journal of Experimental

Child

Psychology,

45, 71-87.

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T. Durso,

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Bjorklund, D.F., & Bjorkhmd, B.R. (1985). Organization versus item effects of an elaborated knowledge base on children’s memory. Developmental Psychology, 21, I l20- I I3 I. Chase, W.G., & Simon, H.A. (1973). Perception in chess. Cognhive Psychology, 4, 55-81. Chi, M.T.H. (1977). Age differences in memory span. Journal ofExperimenru1 Child Psychology, 23, 266-281.

Chi, M.T.H. (1978). Knowledge structutes and memory development. In R. Siegler (Ed.), Children’s thinking: What develops? Hillsdale, NJ: Erlbaum. Chi, M.T.H. (1985). Interactive mles of knowledge and strategies in the development of organized sorting and recall. In S.F. Chipman, J.W. Segal, & R. Glaser (Eds.), Thinking and learning skills: Vol. 2. Research and open questions. Hillsdale, NJ: Erlbaum. Chi, M.T., & Ceci, S.J. (1987). Content knowledge: Its role, representation, and restructuring in memory development. Advunces in Child Developmenf and Behavior, 20, 91-142. Dumo, F.T., & O’Sullivan, C.S. (1983). Naming and remembering proper and common nouns and pictures. Journal of Experimental Psycho1og.y: Learning, Memory, and Cognifion, 9, 497510. Ellis, N.R., Palmer, R.L., & Reeves, C.L. (1988). Developmental and intellectual differences in frequency processing. Developmental Psychology, 24, 38-45. Fidler, J.R., Zechmeister. E.B., & Shaughnessy, J.J. (1988). Memory for frequency of hearing popular songs. American Journal of Psychology. 101 I 3 l-49. Fisk, A.D., & Schneider, W. (1984). Memory as a function of attention, levels of processing, and automatization. Journal of Experimenral Psychology: Learning, Memory & Cognirion, 10, 181-197. Ghatala, E.S., & Levin, J.L. (1973). Developmental differences in frequency judgments of words and pictures. Journal of Experimental Child Psychology, 16, 495-507. Goldstein, D., Hasher, L., & Stein, D.K. (1983). The processing of occurrence rate and item information by children of different ages and abilities. American Journal of Psychology, 96, 229-241. Greene, R.L. (1986). Effects of intention&y and strategy on memory for frequency. Journal of Experimenral

Psychology:

Learning,

Memory

& Cognition,

12, 489-495.

Hanson, C.. & Hirst, W. (1988). Frequency encoding of token and type information. Journuf of Experimenral

Psychology:

Learning,

Memory

& Cognition,

14, 289-297.

Hasher, L., & Chromiak, W. (1977). The processing of frequency information: An automatic mechanism? Journal of Verbal Learning and Verbal Behavior, 16, 173-184. Hasher, L., & Zacks, R.T. (1979). Automatic and effortful processesin memory. Journul of Experimental

Psychology:

General,

108, 356-388.

Hasher, L., & Zacks, R.T. (1984). Automatic processing of fundamental information: The case of frequency of occurrence. American Psychologist, 39, 1372-1388. Hunt, R.R., & Mitchell, D.B. (1982). Independent effects of semantic and nonsemantic distinctiveness. Journal of Experimenral Psychology: Learning, Memory, and Cognition, 8, 8 I87.

Johnson, M.K., Raye, C.R., Hasher, L., & Chromiak, W. (1979). Are there developmental differences in reality monitoring? Journal of Experimental Child Psychology, 27, 120-128. Kausler, D.H., Lichty, W., & Hakami, M.K. (1984). Frequency judgments for distractor items in a short-term memory task: Instructional variation and adult age differences. Journal of Verbal Learning

and Verbal

Eehuvior,

23, 660-668.

Kintsch, W. (1968). Recognition and free recall of organized lists. Journal ogy,

of Experimental

Psychol-

78, 481-487.

Liidberg, M.A. (1980). Is knowledge base development a necessary and sufficient condition for memory development? Journal of Experimenral Child Psychology. 30, 401-410. Lund, A.M., HalI, J.W., Wilson, K.P., & Humphreys, MS. (1983). Frequency judgment accuracy as a function of age and school achievement (learning disabled versus non-learning-disabled) patterns. Journal of Experimental Child Psychology, 35, 236-247.

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and Frequency

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Gmstein, P.A., & Naus, M.J. (1985). Effects of the knowledge base on children’s memory strategies. In H.W. Reese (Ed.), Advances in child.development and behavior: Vol. 19. New York: Academic. Rao, K.V. (1983). Word frequency effects in situational frequency estimation. Journal ofErperimental Psychology:

Learning,

Memory.

and Cognition,

9. 73-8 1.

Sanders, R.E., Zembar, M.J., Liddle, C.L., Gonzalez, E.G., % Wise, J.L. (1989). Developmental effects in the processing of event frequency. Journal OfExperimental Child Psychology, 47, 142-159. Ilersky, A., Jr Kahneman, D. (1973). Availability: A heuristic for judging frequency and probability. Cognitive Psychology, 5. 207-232. Williams, K.W., & Durso, F.T. (1986). Judging category frequency: Automaticity or availability? Journal

of Experimental

Psychology:

Learning,

Memory

& Cognition,

12, 381-396.