Effects of cue associations in concept shifts

JOURNAL

OF VERBAL

LEARNING

Effects

AND

VERBAL

BEHAVIOR

7,474418

of Cue Associations

ROGER W. SCHVANEVELDT~

(1968)

in Concept

Shifts1

AND NEAL E. A. KROLL~

University of Wisconsin, Madison, Wisconsin 53706 An orthogonal design was employed to separate the effects of cue associations and cue dimensions in intradimensional (ID) and extradimensional (ED) shifts. Associations between relevant stimulus cues (words) were varied both between and within dimensions (categories). Two control groups were used to measure nonspecific transfer effects. The results obtained with 150 college students as Ss were: (a) no difference between ID and ED shifts in trials or errors to criterion in the shift; (b) positive transfer with high association between the relevant cues in original learning and shift learning, and zero transfer with low association; and(c) the analyses of Ss’ hypotheses supported the results for trials and errors. The relevance of these data to mediational explanations of shift behavior is discussed.

Concept- and discrimination-learning experiments usually show that intradimensional (ID) shifts are easier than extradimensional (ED) shifts (e.g., Isaacs and Duncan, 1962; Zeaman and House, 1963; Harrow, 1964; Uhl, 1966). One explanation of this ID-ED effect involves verbal mediation processes (Kendler and Kendler, 1962, 1966). According to this view, S implicitly labels the cues presented in the various stimuli. These implicit cue labels, in turn, elicit a higher-order label which is specific to the dimension to which the cue belongs (e.g., a large object is labelled “large” which in turn elicits the implicit verbalization, “size”). Thus when S learns to respond to the positive stimulus, the labels corresponding to the positive cue and the relevant dimension both mediate the overt choice response. A shift in which the dimension label is still appropriate 1 This research was accomplished while both authors were U.S. Public Health Fellows at the University of Wisconsin. The authors are indebted to R. C. Calfee and D. A. Grant for their critical comments on the manuscript. The preparation of stimulus materials and the data analysis were facilitated by the University of Wisconsin Computing Center made available by the Wisconsin Alumni Research Foundation through the University Research Committee. * Now at the State University of New York at Stony Brook. 3 Now at the University of California at Davis.

(an ID shift) should then be easier than a shift involving a change in both mediational responses (an ED shift). An alternative explanation of many of the shift studies, while also involving verbal mediation, consists of merely relating the difficulty of shift performance to the association strength (AS) between the positive cue in original learning (OL) and the positive cue in the shift; i.e., the higher the AS, the easier the shift. Since cues from the same dimension tend to be more highly associated than cues from different dimensions, type of shift (ID vs. ED) has often been confounded with AS. The process involving associations between cues has been designated first-order mediation while the dimensional mediation has been designated second-order mediation (Lachman and Sanders, 1963). The present study was designed to investigate further the effect of AS on shift performance. The use of verbal stimuli permitted. independent manipulation of the strength of intercue associations and type of shift. The effectiveness of the AS variable is taken as a measurement of first-order mediation. The use of verbal stimuli also made it possible to minimize characteristics of stimuli which give rise to other processes thought to contribute to the ID-ED effects (e.g., perceptual observing

475

CUE ASSOCIATION IN CONCEPT SHIFTS

responses ; Zeaman and House, 1963 ; Mackintosh, 1965; Lachman, 1966). Thus the effectiveness of the shift-type variable (ID vs. ED) should be a fairly accurate measurement of second-order mediation. By the orthogonal variation of AS and shift-type, the present study attempts to determine the effects of both first- and second-order mediation in simple concept learning.

(ID) or a different (ED) relevant category for OL and the shift. The AS between the positive word in OL and the positive word in the shift determined the value of the AS variable. Table 1 presents the positive words in OL and the shift for each condition. For any given stimulus there were three irrelevant words, one for each of three different categories. The AS between all words in the relevant categories (in both OL and the shift) was low except, of course, when the experimental condition specified high AS between the positive words in OL and the shift. Further, AS between the words in the relevant categories and words from other categories was low. In order to obtain a sufficient number of words meeting the experimental requirements, the association norms of Russell and Jenkins (1954), Bousfield et al. (1961), Palermo and Jenkins (1964), and Battig (1959) were combined with norms obtained from 122 students enrolled in

METHOD Design. A 2 x 2 x 2 factorial design was employed, with two levels of AS between the positive cue in OL and the positive cue in the shift (high or low AS), two types of shift (ID or ED), and two different word lists. In addition, there were two control groups (one for each TABLE POSITIVE

WORDS

IN

1

OL AND THE SHIFT Type of shift

Associative strength

ID OL-Shift

ED OL-Shift

High

List 1 List 2

HORSE-COW HAND-FOOT

MILK-COW SHOE-FOOT

Low

List 1 List 2

RABBIT-COW FINGER-FOOT

COKE-COW PANTS-FOOT

word list) which were used to determine nonspecific transfer effects. Stimuli. Each stimulus consisted of four words, one from each of four categories. The categories were: (a) List 1: animals, beverages, emotions, and tools; and (b) List 2: body parts,clothing, bugs, and water bodies. The categories are assumed to be analogous to dimensions such as form and color which have commonly been used in shift studies. In both OL and the shift, one category was relevant to the classification of the stimuli into positive and negative. One word from the relevant category was designated as positive and two words as negative. Thus, with animal as the relevant category, HORSE might be positive and LION and TURTLE, negative. A particular stimulus, then, would be classified as positive if HORSE represented the animal category and negative with LION or TURTLE. The type of shift was varied by having either the same

introductory psychology courses at the University of Wisconsin. With high AS words, one word of the pair occurred as a response to the other word 1 l-SO% of the time. For low AS words, the percentage was less than 0.1. In order to maintain some continuity between OL and the shift, one word from each category appeared in both OL and the shift. In the case of the relevant category, the word appearing in both phases was one of the negative words. Each stimulus was constructed by selecting one word from each of the four categories within a list. The selection of words and the sequence of stimuli in OL were random with the following restrictions: (a) an equal number of positive and negative stimuli; (b) the words appearing in both OL and the shift occur only twice in the sequence of 40 stimuli; and (c) two or three words change from one stimulus to the next. This sequence was used for all conditions by substituting words with

476

SCHVANEVELDTAND

the appropriate AS for the various conditions. The four words were randomly ordered, typed in a vertical arrangement on mimeostencil material, and placed in a 2 x 2-inch slide mount. If S failed to meet the criterion of eight consecutive correct responses within the 40 slides, the sequence was repeated without interruption. In the shift, two of the three words from each category were replaced by new words from the same category. The stimulus sequence in the shift was constructed in the same manner as the OL sequence, with the additional restriction that two categories were not logically eliminated through Trial 3. In every case the category relevant in OL was potentially relevant in the shift for at least three trials. The control groups received different categories in OL and the shift to preclude both dimensional and associative transfer, Apparatus. There were four major apparatus components. (a) The S’s response and feedback panel consisted of two levers labeled POSITIVE and NEGATIVE for classification responses, a feedback lamp mounted above each of the levers, and four vertically arranged push-button switches representing the four positions of words in the stimuli. These switches were used by Ss to indicate their hypotheses. (b) Two Kodak Carousel slide projectors presented the stimuli. (c) An IBM 526 Printing Summary Punch machine controlled the feedback lamps and recorded the classification response, the correct response, and the hypothesis response for each trial. (d) Timing and memory circuitry controlled the sequential operation of the other units. A complete description of this type of apparatus is given by Polidora and Main (1963). Procedure. On each trial, the stimulus remained in view until S’s classification response. When S wished to classify a slide as positive, he first pressed one of four buttons to indicate the position of the word he thought was the positive word and then the lever labeled POSITIVE. A negative response consisted of just pressing the lever labeled NEGATIVE. After S’s response the signal lamp above the correct classification lever was lighted for 0.5 set informing S of the correct classification for that slide. No information was given about the correctness of S’s hypothesis response. The next stimulus was presented 5.0 set after the termination of the informative feedback. The Ss were given the names of the categories involved in their problem and were told that the solution would be determined by one of the four categories, with one word from that category being positive and the others negative. No information about the shift was given, and when S met criterion in OL, the shift was introduced without interruption. Subjects. The Ss were 150 students enrolled in introductory psychology courses at the University of Wisconsin. The Ss volunteered for the experiment and

KROLL

were given class credit for participation. Each S was randomly assigned to one of the conditions, with the restriction that there be 15 Ss in each. RESULTS

Skewed frequency distributions in the trial and error data suggested log transformations. However, the analyses of the transformed data yield the same pattern of results as the raw score analyses. Also the same effects exceed the .OSlevel of significance in the analysis of both trials and errors. Original learning. No significant effects were obtained in any of the analyses on the OL data. Overall Pearson product-moment correlations between OL and shift performance range from -.039 to -.044 on the various measures, indicating little or no relationship. Shift. Table 2 shows mean trials to criterion TABLE MEAN

TRIALS

2

TO CRITERION

IN SHIFT

Type of shift Associative strength High Low Average

ID

ED

Average

7.13 11.33 9.23

6.53 13.53 10.03

6.83 12.43

in the shift for the four combinations of shift type and AS. A three-way analysis of variance shows that the effects of shift type, lists, and the interactions involving these terms are all nonsignificant. The only variable producing a significant effect is AS, F(1, 112) = 940.80/ 120.57 =7.80; pc .Ol. Compared with the control groups for nonspecific transfer (mean trials in shift = 13.20), the high-association groups tend to show positive transfer and the low-association groups, zero transfer. Compared with OL (mean OL trials = 24.89), all groups show improved performance in the shift. While Ss’ hypotheses should be related to the number of trials to criterion, the hypothesis

CUE

ASSOCIATION

information supports the analyses of trials and errors and also reveals the effects of AS and shift type in the early trials of the shift. The primary analysis was based on the hypothesis responses on Trial 3 in the shift. Two categories were still possible solutions through Trial 3, and the analysis of Ss hypothesizing one of these categories indicates that the category relationship between the shift cues and the relevant cues in OL (same us different category) had no significant effect on hypothesis choice. That is, Ss were as likely to hypothesize the word from the different category (39 S’s) as the word from the same category (41 Ss). Association strength did, however, have a significant effect, x2 (1) = 6.09; p < .02. In other words, when the choice was available, Ss chose as their hypothesis the cue having a high association with the previously positive cue significantly more often than the low-association cue regardless of category membership (29 Ss vs. 13 Ss). The hypothesis effects on Trial 3 are also present on other trials in the shift. DISCUSSION

On the assumption that verbal stimuli are equivalent to the stimuli typically used in simple concept-learning experiments in terms oftheir ability to elicit second-order mediation, the present experiment found no evidence for second-order mediation. This absence of a second-order mediation effect is somewhat surprising since the categories were specifically identified in the instructions. Conversely, direct associations between cue names were found to affect shift performance significantly. There is also evidence that the association effect occurs with nonverbal stimuli (Lachman, Meehan, and Bradley, 1965; Lachman, 1966). The stimuli in this study afford the possibility of Ss applying dimensions other than the categories specified by E. In the high AS, ED conditions, for example, it is relatively easy to identify a dimension containing both the positive cue in OL and the positive cue of the shift. However, the specified categories should have

IN CONCEPT

477

SHIFTS

been quite salient during OL, since each contained three members and was listed in the instructions, while the “spurious” dimensions were not present until after the shift, if at all. Also, it is quite difficult to formulate verbal labels for the spurious dimensions, while the specified dimensions were labeled in the instructions. If, despite the above arguments, spurious dimensions were used in the high AS, ED conditions, second-order mediation should still show its effect in the low AS groups where there are no salientdimensions other than those listed in the instructions. However, the analysis of S’s hypotheses, which should reflect mediational effects in the early shift trials where mediation should be most prevalent (Jenkins, 1965; Clifton, 1966), gives no indication of an effect of shift type. In conclusion, the present results give reason to question the role of second-order mediation in simple concept learning. This is not to say that Ss will not use second-order mediation in more demanding tasks such as free recall where memory requirements are more severe and where performance can be improved by organizational principles. It should be emphasized that stimulus dimensions may influence shift performance without dimension labeling. One of the salient characteristics of cues on a dimension is that the cues often are presented in the same physical location (Lachman, 1966). The present experiment did show that direct associations between cues are important in determining shift behavior and this effect should be considered in explanations of concept shifts.

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