Interactive effects of working memory span and text context on reading comprehension and retrieval

INTERACTIVE EFFECTS OF WORKING MEMORY SPAN AND ‘IEXT CONTEXT ON READING COMPREHENSION AND RETRIEVAL FRANCIS J. DI VESTA

MATTHEW J. DI CINTIO ELMHURSTCOLLEGE

ABSTRACT:

This study examined the effects of the interaction

ory span (WMS) and assigned perspectives

tion from a passage under the same or alternative measured

in terms of the correspondence

assigned perspective perspective.

(encoding

relevance).

of working mem-

(contexts) on the retrieval of informaperspective.

of recalled

The effects were

ideas to the

originally

Control subjects were not assigned a

WMS was found to be related to the amount of information

on each of two recall trials. Compared context significantly

facilitated

levels. A switch in perspective

to a no-context

recalled

control group, the assigned

recall of corresponding

information

at all WMS

on the second recall trial led to increased recall of

new ideas for readers at all WMS levels. The

most

important

finding,

however,

was that unlike the high and medium WMS groups, the low WMS group omitted a significantly larger number of encoding-relevant ideas on the second recall trial, compared to the number produced on the first recall trial. The implications of these findings for practices of providing in test administration

contexts in reading comprehension

and

were noted. The findings provide support for the premises

of WMS capacity and selective attention theories.

The present study falls within the framework of aptitude-by-treatment interaction (ATI) research (Cronbach & Snow 1977). It assesses the influence of contextual infor-

Direct all correspondence to: Francis J. Di Vesta, Box 10387, Calder Square, State College, PA 16805. Learning and Individual Differences, Volume 9, Number 3, 1997. pages 215-231. All rights of rep~ductfon in any form reserved.

Copyright @ 1997 by JAI Press Inc. ISSN: 1041-6080

216

LEARNINGANDINDIVIDUAL DIFFERENCES

VOLUME 9, NUMBER 3,1997

mation on acquisition and recall of information in order to explore the reIationship between individual differences in working memory span (WMS) and recall of text. The design of the study was intended to address the following questions: (1) Will assigned perspectives in reading help low WMS readers? (2) Will multiple perspectives in reading help high WMS readers but hinder recall of low WMS readers? With respect to low WMS readers, will they have (a) low recall of aI1 ideas, (b) low recall of information related to only one perspective (in a condition where perspectives are switched between two recall tests), and (c) low recall of the old perspective ideas due to being asked to recall the material from a new perspective? Perspectives (contexts) support learning and comprehension by providing unifying themes for organizing and integrating text content. These themes (a) guide attention to relevant details, (b) prime activation of specific related ideas, and (c) enable a basis for evaluating which information in a text is relevant to the goal. By establishing a framework for interpretation, the need for controlled (deliberate) processing is reduced. Accordingly, storage and processing space is released for understanding and comprehension.

ASSUMPTIONS The reduced capacity of low WMS Iearners constrains their learning. Compensation for this constraint are achieved by perspectives, contexts, orientations, headings or organization which are potentially capable of providing for chunking or structuring of text (Lee-Sammons, & Whitney 1991). However, often, as in testing, acquisition occurs within one perspective and recall occurs within a different perspective. Such switching at retrieval limits the recall of details related to the perspective existing at acquisition, creating opportunity for influencing the effects of primacy, recency, interference or intrusions on recall. Changes in perspectives increase processing demands with corresponding increases in the opportunities for miscuing, delaying or interrupting efficient processing. The recall of high WMS learners is less affected than recall of low WMS learners when a perspective is withdrawn or replaced. In fact, it can be reasoned that for high WMS learners a new perspective may facilitate recall. The larger capacity enables high WMS learners to process and store processing products associated with more than one perspective. Further, high WMS learners rely less on assigned abstract perspectives (contexts) and more on metacognitive ability for strategies that increase salience and attention to conceptually important items (Reynolds 1992).

RATIONALE Early accounts of working memory (WM) emphasized storage of new items for later retrieva1 and the storage of partial and final products as they were produced (Atkinson & Shiffrin 1968). Current accounts (Baddeley 1986; Just & Carpenter 1992; MacDonald, Just, & Carpenter 1992) include processing operations (WMS). Since working memory capacity is limited, it easily becomes encumbered by both storage and processing demands. When easy tasks are performed, storage and processing work in concert, unconstrained by capacity. With more difficult

WORKlNG MEMORY SPAN

217

tasks storage and/or processing requirements may place excessive demands on memorial resources. Integration of details taxes processing demands. Retaining the products of processing taxes storage limitations. If capacity constraints are exceeded, efficiency of storage and/or processing may be sacrificed, differentially allocated, scaled down, or otherwise degraded (Just & Carpenter 1992). The extent to which performance is affected by WMS depends upon total capacity, task requirements, and the availability of learner strategies that may compensate for limitations in WMS.

INDIVIDUAL DIFFERENCES MEASURES OF WORKING MEMORY SPAN The measure of WMS used in the present study was originally developed (Daneman & Carpenter 1980,1983) in response to the need for understanding the influence of working memory capacity in linguistic processing. The development of the measure was based on the rationale that WMS includes both processing and storage requirements. Processing requirements include decisions about the orientations of the text which produce products related to comprehension. These products must be stored as frameworks for continued reading. Consistent with the assumption that processing and/or storage demands have the potential for taxing storage capacity, the measure of individual differences in working memory span requires the storing of the products of processing several sets of two to six sentences. Thus, the reader (1) judges (i. e., processes) a sentence as meaningful or non-meaningful as it is read, and then (2) remembers (stores) the Iast word of the sentence until it is to be retrieved. After all sentences in a set are read the last word in each of the sentences in a set are recalled. The total score on the entire test indexes the relative capacity available for processing and storage of processing products. We considered the possibility that other factors such as verbal ability and word knowledge, may be related to scores on the WMS test. However, an examination of the evidence indicated that measures of WM processing efficiency (inferencing and word recall) are related more to comprehension measures that assume active processing (reading span) than to passive measures (word knowledge) (Dixon, LeFevre, & Twilley 1988; Mason & Miller 1983; Perfetti & Goldman 1976). On the basis of such evidence and following Tirre and Pena (1992) we concluded that “the memory span test measures functional working memory in reading” (p.462). Accordingly, the WMS test was selected as the measure most consistent with the conceptualization of the individual difference variable used in the present study.

WMS, CONTEXT AND READING COMPREHENSION Comprehension and retrieval of text information involve similar cyclical sequences of processing and storage to those described in the previous section. Contexts or perspectives facilitate comprehension and retrieval by providing

218

L.EARNING AND iNDlVlDlJAL

DIFFERENCES

VOLUME 9, NUMBER 31997

structures for (a) activating relevant, related information, (b) specifying the focus of attention, (c) specifying what information is to be selected, (d) relating new information to prior knowledge, or (e) facilitating the identification of word or passage meanings, conceptual relations, and propositions. Periodic retrieval of the products of these processes, required in reading text, has the potential of overloading the WM capacity. Low WMS readers are at a disadvantage when two perspectives are used. Being required to identify which of two representations (the one used at acquisition or the one required at recall) to employ in recall strains their capacity. The problems of (a) sorting out appropriate alternative representations, (b) evaluating the correctness of interpretations, and/or (c) deciding details to be associated with the perspective adds to the strain. Any wiIl influence the quality and quantity of specific information retrieved and thereby influence measures of comprehension. Switches in perspective that may occur when reading moderately or very complex passages, have the potential of taxing working memory capacity. Additional demands are made in order to identify, maintain, evaluate and repair contextually-related information. Low WMS readers, accordingIy, are hypothesized to have (a) low recall of all ideas, (b) low recall of information related to only one perspective (in a condition where perspectives are switched between two recall tests), and (c) low recall of the old perspective ideas due to being asked to recall the material from a new perspective. Switching is less of a problem for high WMS readers (Sharkey & Mitchell 1985). Their higher capacity permits the flexible execution of processing and storage of processing products according to whatever reasonable conceptual bases are indicated (Reynolds 1992).

HYPOTHESES The foregoing rationale suggests the hypothesis that assigned perspectives (contexts, or unifying themes) provide instructional support for the more limited storage and processing capacity of low WMS readers (see also LeeSammons & Whitney 1991). However, multiple perspectives while facilitating retrieval of high WMS readers may hinder retrieval by low WMS readers. Capacity limitations coupled with the increased storage and processing demands of selection, evaluation, and repair all take their toll on readers with low WMS. Accordingly, it was hypothesized that low WMS readers will depend on the most recent available perspective for recall. In the face of lower capacity, processing and storage demands result in lowered retrieval of a11 information or ideas by the low WMS reader. Lower capacity restricts recall of information related to one perspective (either assigned at acquisition or at retrieval). As hypothesized for this study ideas related to a new, more recent perspective are recalled by the low WMS reader at the expense of available ideas related to an old perspective. We hypothesized, accordingly, that the low WMS reader would omit more details based on the perspective assigned at acquisition than would the high WMS reader.

WORKlNG MEMORY SPAN

219

METHOD DESIGN The o~eru~ldesign of the study was a 3 x 2 x 3 x (2) x (2) mixed analysis of variance (ANOVA). The between-subjects variables were Working Memory Span (low, medium, or high WMS), Switch Treatment (no-switch or switch), and Presence of Perspective (burglar, homebuyer, or control). The Control provided a baseline (i. e., it was not assigned a perspective at any time either in the reading of the passage or in the recall tasks). The within-subjects variables for the anaIysis were Time of Test (first and second recall), and Encoding Relevance of ideas recalled {encoding-relevant and encoding-irrelevant). Encoding relevance refers to the relationship of what was recalled to the ideas associated with the originally assigned perspective in thefirst task (i.e., the initial reading task).

PARTICIPANTS The participants were 180 undergraduates from a large introductory educational psychology course. The data were collected during two semesters: 80 participants were given the experimental tasks in one semester and 100 participants were administered the tasks during the next semester. There were 10 participants in each of the 18 treatment groups when homebuyer, burglar and noperspective are considered as separate conditions. Since participants were selected during two semesters the possibility of the introduction of systematic error variance necessitated an initial ANOVA blocking on the semester-variable. None of the main effects or interactions from this analysis were significant: all F-ratios were < 1.00. Subsequent analyses were based on coIIapsing all data on this variable. The tasks were administered in groups varying in size from 8-15. In any group session, the treatments were assigned to participants in an unscheduled order to achieve random assignment. Assignment of participants to a given treatment was made by reference to a table of random numbers. Randomization was recycled at n + 1 treatments in order to retain an equal number of participants in each cell during the course of the experiment. Points toward course credit were earned for participation in the study. Participation was in accordance with the University policy for the Use of Human Subjects.

MATERIALS The materials consisted of a test of individual differences reading task, recall tasks, and a spatial reasoning task.

The Measure of Working Memory Span (WMS). Individual employed

a dual task procedure

following

in working memory, a

differences in WMS that employed by Turner and Engle

220

LEARNING AND INDIVIDUAL DIFFERENCES

VOLUME 9. NUMBER 3,1997

(1989). Briefly, the respondent read sets of sentences. Each sentence was about 14 words in length. As each sentence was read silently by respondents they rated it for comprehensibility. After all sentences in a set had been read the last words in all sentences within the set were recalled. Thus, the WMS test required the respondent to: (a) determine whether each sentence, as written, within a set of two to six sentences, “made sense” or “was nonsense;” (b) remember the last word of each sentence; and (c) recall in writing the last words of all sentences within the set after the last sentence was presented. The instructions told the participants of these requirements. In addition, the subjects practiced taking the test on five unrelated sets before the actual task was given. There were 60 sentences in the test, Each was 13-16 words in length. The sentences were presented to the subjects using a 35-mm Kodak carousel slide projector with an automatic timing device. Half of the sentences were in the passive voice and half of the sentences were in the active voice. Sentences that made sense were semantically and syntactically correct. Nonsense sentences were constructed by scrambling the 4-6 words preceding the last word of an otherwise meaningful sentence. The sentences were presented in blocks of 2,3,4,5, and 6 sentences. There were three sets for each block. For example, the first set was comprised of two sentences, the next of three sentences and so on. The last set was comprised of six sentences. The following is an example of a set of two sentences: 1. 2.

The magazines were stacked so high that a rumbling truck nearby sent them spilling off the desk. (Complete sentence) The wife was looked after by her adoring husband to make received no she sure harm. (End of sentence scrambled)

The responses to the WMS were scored according to the total number of the last words correctly recalled across all sets. In the above example, the participant would recall desk and harm. These scores were used to determine the reading span level, defined as the level at which the subject correctly recalled all of the final words of the sentences on at least two of the three sets (Turner & Engle 1989). The total number of words correctly recalled has also been used as the WMS measure. The two scores are highly correlated but since the latter provides a more refined measure it was used to divide the subjects in the present study into three equalsized groups: low, medium, and high WMS (see Lee-Sammons & Whitney 1991; Turner & Engle 1989 for a corresponding procedure). The division of the total sample (N = 180) into three groups (n = 60) was made at the 33rd and 66th percentiles of the distribution of WMS test scores. The lowest third comprised the low WMS group (M = 27.03, SD = 4.20, Range = 17-33), the middle third comprised the medium group (M = 38.51, SD = 3.01, Range = 3443) and the highest third comprised the high WMS group (M = 47.97, SD = 4.11, Range = 44-58). These summary data are based on collapsing over both semesters since the mean scores for the low, medium and high groups were precisely the same for each semester.

221

WORKlNG MEMORY SPAN

Reading and Recall Tasks. Although we were not concerned with examining the effects of perspective, per se, as did Pichert and Anderson (1977) their passage was used to manipulate the contextual perspectives and the switch in perspectives. As an ambiguous passage the passage could be read meaningfully from the perspective of a home buyer or a burglar and thus the perspectives could be switched easily. The passage was comprised of 331 words and 20 sentences. Within the passage there were 13 ideas relevant to each perspective.

PROCEDURE The pool of participants was administered the WMS test prior to the conduct of the experiment. Assignment to WMS groups (high, medium and low) was made on the basis of the scores from this test. Participants in the treatment groups were randomly assigned, within each WMS level, to read from one or the other perspective, i.e., one-half received the homebuyer perspective and one-half received the burglar perspective. The control group read the passage without receiving a perspective. The instructions were to read the passage carefully for comprehension. Those who received the homebuyer or burglar perspectives were told that thinking of the passage from the perspective would help them remember the main ideas. Control subjects were simply toId to read for comprehension using their customary study procedure for such materials. Three minutes were allotted for reading the passage. After reading the passage the participants were asked to “recall everything that could be remembered from the passage, trying to come as close to the original as possible in their recall.” Immediately following the first recall trial, the participants completed the Flags test (Thurstone &Jeffrey 1956). Each item of the test required matching a standard flag with one of five alternative rotations. This non-verbal task required five minutes to complete. It was used simply as a buffer to minimize recall of recently acquired information that might have been retained in short-term memory. The second (delayed) recall trial was then administered. The Switch treatment was introduced at this time. All participants, including those in the Control group, were once again asked to recall as much information as possible from the passage. Deliberate instructions were given to “attempt to recall as much information as possible including information not recalled the first time.” Participants in the no-switch condition were reminded to keep the original perspective with which they read the passage in mind. They were told further that recalling the information a second time would help in retrieving more information. Participants in the switch condition were provided with the alternate perspective. They were told that thinking about the story from the different perspective might help them remember additional information which they had not recalled the first time. The control (no-perspective) was given the same instructions as the other groups without reference to the perspective. They were simply instructed to recaI1 as

222

LEARNING AND INDIVIDUAL DIFFERENCES

VOLUME 9, NUMBER 3,1997

much information as possible and to think of information that may not have been recalled on the first trial. The first and second recall tests were scored for number of Encoding-relevant (those ideas corresponding to the perspective on the reading trial) and Encodingirrelevant (those ideas corresponding to the perspective not used on the reading trial) ideas. The protocols were also scored for previously unrecalled ideas (i.e., new ideas which appeared in the second recall, but not in the first recall), and omitted ideas (i.e., ideas which appeared in the first recall, but not in the second). To obtain these scores two lists of details or ideas were made based on the specific sentences in the passage. One list was related to the homebuyer perspective and the other list was related or to the burglar perspective. Individual scores were scored as ER or EI depending upon the assigned perspective. Scores were labeled encoding-relevant (ER) if they were consistent with, and encoding-irrelevant (EI) if inconsistent with the perspective assigned at the time of the initial reading. These labels were applied irrespectively of the perspective used for the second retrieval trial, where the switch/no-switch conditions had been induced. The control subjects papers were scored by assigning them randomly to either one or the other of the two perspectives and scoring their papers accordingly. These scores represented a baseline of amount recalled without benefit of a perspective. Interrater consistency based on “blind” scoring of 35 randomly selected protocols indicated 98% agreement, for each of the two sets of scores (ER and EI), between two raters. Percentages rather than raw scores were used in all analyses and summaries since they provided a convenient base for comparison across conditions and comparison with results from other studies where percentages were typically used. All percentages were based on a constant total.

RESULTS Analyses were made of: (a) the number of encoding-relevant (ER) and encoding irrelevant (EI) ideas reported in the first recall trial; (b) the number of ER and EI ideas reported on the second recall trial; (c) ideas, not reported on the first recall trial, but which were reported on the second recall trial; and (d) ideas, omitted on the second recall trial, but which were reported on the first recall trial. (ER and EI responses, respectively, were defined throughout the experiment as corresponding [ER] or not corresponding [EI] to the perspective originally assigned to the passage.) PERFORMANCE

ON THE FIRST RECALL TASK

The initial analyses performed were used to compare performance of each WMS level to that reported in other studies. The analyses of the first recall trial data were used to establish replications of effects associated with assigned perspectives and with WMS levels. The questions asked were: Was the effect of perspective on recall

WORKING MEMORY SPAN

induced? Were manipulations?

treatment

223

groups

equivalent

in recall

prior to the

switch

Analysis Number 1: The Relation of WMS and Perspective to Initial Comprehension. The number of ideas recalled on the first recall trial was analyzed via a 3 x 3 x 2 mixed analysis of variance to determine the discriminability of the WMS test and to determine the replicability of the effects of the perspective on comprehension. The between-subjects variables were: Working Memory Span (WMS) level (low, medium, or high), assigned Text Perspective (burglar, homebuyer, or control/noperspective) and Switch (switch or no-switch) treatments. It should be noted that the responses of the Control (no-perspective) group on the first recall trial, by controlling for the presence of a perspective (i.e., a perspective was not assigned to the passage) provided a “baseline” of amount recalled under “normal” conditions. The analysis yielded a significant main effect due to the WMS on overall recall, F(2,171) = 34.62, MS, = 188.64, indicating that the total percentage of idea units recalled was related to the WMS. The means were 47.78, 52.75, and 65.38, for the low, medium, and high levels of the WMS groups, respectively. The difference between each of the M’s was significant (Newman-Keuls cu = 4.7, p < .05). The significant differences in the total percentages of ideas recalled as a function of WMS supports the validity of the WMS task as a measure of individual differences; over all treatments, levels of WMS were related to percentage of ideas recalled (see also Tirre & Pena 1992). The analyses also yielded a significant main effect of Text Perspective on recall, F(2,171) = 5.09, MS, = 188.64. The assignment of a reading perspective, whether homebuyer or burglar, enhanced recall to a significantly greater extent (homebuyer M = 58.67 and burglar M = 56.36) than when a reading perspective was not assigned (control M = 50.88). Note that each of the perspective groups recalled more than the no-perspective group. The effects of the homebuyer and burglar perspective treatments were not significantly different from each other but each was significantly different from the Control group mean (Newman Keuls cv = 4.7). None of the other effects in this analysis were significant. These initial analyses clearly showed that, in answer to the first question, the perspective had a significant effect on the amount recalled. In answer to the second question, the analysis showed that the groups were equivalent on all other treatment variables and any subsequent significant effects could be attributed to treatments. The analysis described in the next paragraph extends these conclusions by including an analysis of the type of responses recalled (i.e., whether or not the responses corresponded to the assigned perspective).

Analysis Number 2: The Effects of Perspective on Recall of ER and El Responses. The question asked in this analysis was, “Will the assigned perspective yield higher recall of ideas corresponding to it than to ideas related to the alternative perspective?” In order to examine the effects of the switching variable on the second recall trial, this analysis was necessary to support the assumption that each of the two assigned perspectives would yield more ER than EI ideas (i.e., more ideas associated with the relevant than the irrelevant perspective).

224

LEARNINGANDINDIVIDUAL DIFFERENCES

VOLUMEQ,NUMBER3.1997

The responses were analyzed via a 3 x 2 x 2 x(2) mixed-ANOVA. The betweensubjects variables (n = 10 in each cell) were WMS (high, medium or low), Original Text Perspective (homebuyer or burglar) and Switch (switch or no-switch in perspective at second recall). (Although the Switch treatments had not yet been introduced, the incorporation of this variable in the analysis was necessary to establish the equivalence of the groups on the first recall task. Note that the Control group was not included in this analysis.) The within-subjects variable was Encoding Relevance (ER or EI) of ideas recalled. The analysis yielded a significant main effect on Encoding-Relevance of ideas (i.e., ER or EI) recalled, F(1,lOS) = 15.83, MSe = 258.94. Significantly greater percentages of ER than of EI ideas were recalled within each perspective: the homebuyer perspective ER M = 62.57 and EI M = 53 72 ; the burglar perspective ERM = 71.27 and EI M = 45.89 (t = 2.95, df= 118, p < .04). This finding shows that the effect of the presence of a perspective was effectively induced. The interaction of WMS, Switch Treatments and Encoding Relevance was not significant, F(2,108) = 0.23, MS, = 258.94 in the analysis of data for the first trial. (The reader is reminded that the “Switch” treatment was not manipulated until the second task.) Within each level of WMS, the Switch treatment conditions (Noswitch or Switch) did not differ in the percentage of ER or EI recall. Thus, all groups within a WMS level, including those to be used in the subsequent Switch treatments, were assumed to be equivalent in their performance on the first recall task. The analysis of the data for the first recall trial establishes further support, in addition to that found in Analysis 1, for the assumptions regarding the functioning of the WMS levels, the effects of assigned perspectives, and the general equivalence of groups. Consequently, any significant effects identified in the analysis of data from the second recall trial could be attributed to associated treatments.

Analysis Number 3: Performance on the Second Recall Task. A 3 x 2 x (2) mixedANOVA was made to determine the effect of the switching treatments on the second recall trial. The between-subjects variables were WMS (high, medium and low) and Switch treatment (No-switch and Switch). The within-subjects variable was Encoding Relevance. There were 20 subjects in each cell of the analysis (N = 120). Since the effects of the two perspectives (homebuyer and burglar) were not significantly different in the analysis of the first recall trial, the data for the two were combined and referred to as the “assigned perspective” group. None of the main effects in this analysis were significant. The two significant interactions are related to the hypotheses of the study and, accordingly, will be discussed below. The interaction of Switch treatments x Encoding Relevance (ER and ET) was significant, F(1,108) = 22.77, MS, = 241.16. The means comprising this interaction are as follows: For recall of ER ideas M = 68.72 for the no-switch group and M = 59.19 for the switch group. For the recall of EI ideas: M = 49.32 for the no-switch group and M = 58.92 for the switch group. (Newman-Keuls cu = 7.38, ~7= .05, for the difference between ER and EI means and Newman-Keuls cv = 5.61, p = .05 for the difference between switch and no-switch treatment means.) In summary: (a) The mean recall of the no-switch group (having the advantage of the same perspective and repeated recall) was significantly higher than the mean recall of the switch

225

WORKINGMEMORY SPAN

treatment. (b) Recall of ER and EI ideas was significantly different for the noswitch group but was not significantly different for the switch group. This interaction was qualified by the significant interaction of WMS x Switch x Encoding Relevance, F(2,lOB) = 3.81, MS, = 241.16. The means comprising this interaction are summarized in Table 1. There it can be seen that the means for the switch treatments, within the medium and high WMS levels, did not differ significantly in the percentage of ER information recalled. However, the differences between switch treatments within the low -WMS level were dramatic and provide reliable support for the primary hypothesis that the low WMS learners depend on the perspective or context applied at retrieval resulting in the failure to retrieve information initially learned. The low WMS/ switch subjects recalled significantly (Newman-Keuls c’u = 23.13, p = .05) fewer ER (M = 37.67) ideas on the second recall trial than did the low-WMS /no-switch subjects (M = 63.38). A switch in perspectives also results in overall lower recall of ER responses by the low WMS subjects: in the switch condition significantly fewer ER (M = 37.67) ideas were recalled on the second trial than on the first trial (M = 58.44). The substantial change in the kind (ER and EI) of information recalled by the low WMS subjects in the switch condition, by comparison with all other groups,

TABLE 1 Mean Percentage of Encoding-Relevant and Encoding-Irrelevant Ideas Recalled by WMS and Switch Treatments on the First and Second Recall Tasks Encoding Relevance of Ideas Recalled* First Recall Task WMS

Encoding-Relevant

Level

Treatment

Second Recall Task

Encoding-Irrelevant

Encoding-Relevant

Encoding-Irrelevant

M

SD

M

SD

M

SD

M

SD

No-switch

62.3 1

19.19

42.14

21.77

Switch

58.44

18.76

40.65

18.02

Control**

41.79

13.44

46.47

18.96

63.38 37.67 49.24

20.06 25.88 13.54

41.19 50.1x 47.62

23.99 20.79 18.15

No-switch

64.64

19.93

49.5 I

15.78

67.80

Switch

65.01

18.38

47.68

17.12

65.36

Control**

46.16

15.95

47.26

14.37

49.06

19.69 24.54 14.59

47.90 57.06 52. I I

16.70 17.72 14.61

No-switch

72.03 79.11 62.04

17.88

58.05

18.59

74.97

18.21

60.17

25.72

74.5 I

15.70

64.48

13.01

65.72

16.76 24.36 14.38

58.85 69.42 69.49

20.02 22.36 14.34

LOW

Medium

High Switch Control** Notes:

*The reader is reminded initial

that “encoding-relevant”

reading of the passage. Encodin&relevant

EI are arbitrarilly

assigned classifications

scored by either the burglar or homeowner

is alwavs defined in terms of the Dersoective used at the time of the refers to all other ideas recalled. fhe

for the control.

key (assigned at random 1o a given partupant’s

ply provide a base line for recall under normal reading. to trearments.

and

responses). The means sim-

The data for the control group demonstrate

same scores are obtained regardless of the scoring key used and that significant effects could be attributed

n in each group is 20. **ER

Responses were scored for number of ideas produced when

differences

that essentially

supporting

hypothesized

the

226

LEARNINGANDlNDlVlDlJALDFFEUENCES

VOLUME 9. NUMBER 3.1997

clearly supports the hypothesis that the lower WMS learners depend on context (i.e., assigned perspective) at retrieval, This finding implies that the extra processing demands of the switch in perspectives significantly,hinders the recall of the low WMS.

Analysis Number 4: Analysis of Previously Unrecalled Information. In order

to further examine the loci of differential performance due to switching perspectives analyses were made of previously ~4~recul~e~i~for~fffio~ and urniffed information. The results of these analyses are summarized in the subsequent sections. They are intended to provide answers to the questions, (a) “Does the provision of a second perspective at retrieval (e. g. as in the Switch treatment) cue the production of additional information relevant to that perspective? (b) Is the information cued by the second perspective, in addition to or at the expense of information originally recalled for the first perspective ?“ (c) “Will low WMS/switch readers have lower recall of information related to the intially assigned perspectives?” Separate 3 x 2 analyses were made of unrecalled EI and ER ideas on the second recall trial that were not ~~~~~ce~ on the first recaI1 trial. The betweensubjects (N = 120) variables for each analysis were WMS levels and Switch treatments (Switch and No-switch). This analysis of EI ideas yielded a significant main effect due to the Switch treatments, F(l, 114) = 23.04, MS, = 110.00, p < .Ol. The mean number of previously unrecalled EI ideas was significantly (f = 5.38, f-’ < .Ol) higher for the Switch group (M = 14.19, SD = 16.34) than for the Noswitch group (M = 5.53, SD = 12.26). An ANOVA of ER ideas showed none of the differences due to WMS levels, Switch treatments, or their interaction were significant (~7 > .OS). The mean percentage of previously unrecalled ER ideas was M = 6.19 and of EI ideas the M = 5.53, t = 0.70, ~7> .lO. It should be noted that, the switch group recalled significantly more EI than ER ideas (M = 14.19 and M = 4.21, respectively; whereas, the no-switch group recalled equal numbers of EI and ER ideas (M = 6.19 and M = 5.53, respectively) These findings support the hypothesis that a second, perspective at retrieval (i.e., the Switch treatment) cues the production of additional il~formation relevant to

TABLE 2 Mean Percentage of Previously Unrecalled Encoding-Relevant and Encoding-Irrelevant Ideas by Switch Treatment Knwdin,q

Reievmrce

of Ideas

Treatmcm*”

Switch No-switch Control Notes:

*The reader is reminded that “‘~ncodin%-relevant” is always defined I” terms of the perspective used at the tme of the mitial reading of the passage. Encoding-irrelevant refers to all other ideas recalled. This analysis collapses over WMS groups and perspective treatments. ** The n for each treatment in this analysis is 60. Differences greater than 4.43 are significant. p c .05. Tukcy.

WORKING MEMORY SPAN

227

that perspective. However, the relation of WMS levels to the effects of switching perspectives on recall is identified in an analysis of ideas omitted on the second recall trial.

Analysis Number 5: Analysis of Omitted Information. In view of the finding that a second perspective increases recall of additional ideas, the question was then asked, “Does a second assigned perspective result in decreased reporting of ideas associated with the first perspective. 7“ “Are differences between the first and second recall related to WMS level?” These questions were relevant to a test of the hypothesis that readers with low WMS compensate for capacity limitations by depending on the support provided by the most recent (new, immediately available) perspective. It was hypothesized that such changes would be at the expense of recall of ideas associated with the first perspective. To test this hypothesis two separate 3 x 2 ANOVA’s were made of percentages of ideas omitted on the second trial that had been initially reported on the first trial. The between subjects variables were WMS levels and Switch treatments. Analyses were separately made of omitted ideas [ideas that were recalled on the first recall trial but were not recalled (i.e., omitted) on the second recall trial]. These analyses were made to test the hypothesis that readers with low WMS compensate for capacity limitations by depending on the support provided by the most recent (new, immediately available) perspective. The analysis of omitted ER ideas indicated a significant main effect due to Switch treatments, F(1,114) = 11.98, MS, = 210.00, p >.OOl. The Switch group omitted a greater percentage of ER ideas (M = 13.64, SD = 0.19) than of EI ideas (M = 3.68, SD = 0.07). The difference of 9.43 between these two means is significant (p < .OOl). The ANOVA of omitted EI ideas was not significant for differences among WMS levels (F(2,314) = 1.55, MSe = 90.00, p > .lO), between Switch treatments (F(1,114) = 1.88, MSe = 90.00, p > .lO) or within the interaction of WMS x Switch treatments (F(2,114) < 1.00, MSe = 90.00) . The analysis yielded a significant main effect of Encoding Relevance of Omitted Ideas, F(1,117) = 9.78, MS, = 144.50. Overall, more ideas associated with the initial encoding perspective (M = 6.65) were omitted from the second recall protocol than ideas associated with the alternate perspective (M = 3.46). These data support further the finding that the apparent advantage of the assignment of a second perspective is accompanied by omission of ER ideas.

The Effects of WMS, Switch in Perspectives and the Omission of Ideas in Recall. The findings described above are qualified, further, by the significant interaction of WMS x Switch treatment in the analysis of ER ideas, F(2,114) = 3.52, MS, = 210.00. The mean percentages of recall of ER ideas represented in the interaction of WMS x Switch treatment are displayed in Table 3. There it can be seen the low WMS subjects in the switch treatment omitted a large percentage of previously recalled ER ideas (M = 24.89). In comparison, the low WMS in the no-switch treatment omitted relatively small percentages of ER (M = 4.31) and EI (M = 6.09) ideas; the differences in this comparison were not significant. (The multiple comparisons of differences in these analyses were made via Newman-Keuls, cu = 11.92, p = .05.)

228

LEARNING AND lNDlVlDUAL

DIFFERENCES

TABLE 3 Mean Percentage of Omitted Encoding-Relevant Encoding-Irrelevant Ideas on the Second-Recall

VOLUME 9. NUMBER 3,1997

and Task

Encoding Relevance of Ideas Omitted* WM.7

Encoding-Relevant

Level

Treatment

Encoding-b-relevant

M

SD

M

SD

No-switch Switch Control**

4.31 24.89 1.65

5.76 25.94 3.54

6.09 4.31 1.15

15.34 6.68 5.16

No-switch Switch Control**

3.12 8.24 0.68

9.30 13.18 2.1 I

8.14 4.28 1.27

13.79 7.73 2.63

No-switch Switch Control**

4.16 9.74 0.95

10.64

19.71 4.1 I

2.94 2.22 0.68

5.88 6.10 2.11

Low

Medium

High

Notes:

*The

reader is reminded

initial

reading of the passage. Encoding-irrelevant

and El are arbitrarily

that “encoding-relevant”

assigned classifications

is always defined in terms of the perspective

used at the time of the

refers to all other ideas recalled. The n in each treatment

is 20. ** ER

for the control group. Responses were simply scored by either the home-

buyer or burglar key (randomly

selected) for number of ideas produced. The means provide a base line of the results for

normal reading

with the results of the experimental

for comparison

treatments.

This significant interaction was relevant to testing the hypothesis that the locus, of dependence on assigned perspectives is in the low WMS group. The hypothesis that the added demands of the switch strains memory capacity of the low WMS learners, thereby resulting in increased dependence on the second assigned perspective and less on the initally assigned perspective, was clearly supported.

DISCUSSION Following a switch in perspective, low WMS learners failed to produce additional ideas relevant to the initially induced encoding perspective. They relied more on the salient, assigned retrieval perspective than did their counterparts with higher WMS scores. This outcome suggests a compensatory mechanism that functions to by-pass available capacity constraints and, thereby, avoid overloading. The adoption of the new perspective alleviates the necessity of retaining two contexts for retrieval. The retrieval of different classes of ideas is constrained by the immediately available encoding perspective (i.e., the assigned perspective). In comparison, high WMS influences retrieval by allowing consideration of alternative contexts. A new perspective does not hinder the retrieval of other available information. Active processing can occur flexibly and with little limitation on the ability to store processing products. These cumulative benefits suggest

WORKING MEMORY SPAN

229

that less external support in the form of text-based cues may be helpful in retrieval. Nevertheless, when they are available, they will be used more by high WMS readers than by low WMS readers. Conversely, the benefit to the low WMS subjects, provided by the assigned perspective, is at the expense of retrieving available ideas associated with earlier representations. Thus, the shift in the pattern of recall, following the switch, by the low WMS subjects was due to the omission of (or at the expense of) previously recalled information, rather than to an increase in the recall of previously unrecalled information. “If capacity limitations force a choice of what information to process extensively, it makes sense to give more attention to [whatever perspective is assigned at the time of retrieval] ” (Lee-Sammons & Whitney 1991, p. 1080). Without the constraints of perspectives, as in the control group, information was recalled equally on both trials, thereby reflecting the effects of repetition. Nevertheless, in the absence of assigned perspectives (contexts) the total percentage of ideas recalled was considerably less at all WMS levels than it was when the reading and retrieval were accompanied by an assigned perspective.

SELECTIVE AllENTION

STRATEGIES

Although not designed to do so, the data provide evidence supporting Reynolds’ (1992) theory of selective attention. In that theory, four components of reading comprehension are assumed to affect selective attention strategy. They are: metacognitive

ability-(+)

saZience-(+)uttention

-(+)

learning outcomes.

Applied to the present framework, this theory implies that readers must have metacognitive awareness (understanding the task) to respond to directions. Taking the perspective provides a theme or context, increases saliency or relevance of some available information (i.e., some information is made to “stand out” over other information). The perspective directs attention (intensity, duration, and ratio of conceptual to perceptual focus) to some details over others. The consequent selectivity of attention leads to differential outcomes in learning, comprehending or, as demonstrated in the present study, in retrieval. Each component has the potential of increasing processing demands on working memory. However, a prescribed context has the advantage of freeing the reader from making decisions about the underlying theme. The learner is led to a relatively effortless selection of items made salient by the context. Although the results support the assumption that context compensates, in part, for capacity constraints, they also provide converging evidence for Reynolds’ (1992) conclusion, i. e., although a higher ratio of conceptual to perceptual focus is devoted to all items at acquisition, attention at retrieval is devoted only to items made salient by the context.

230

LEARNlNGANDINDIVlDUAL DIFFERENCES

VOLUME 9, NUMBER 3.1997

CONCLUSIONS The results of this study provide support for the hypothesis that individuals with low memory spans are particularly dependent on an assigned (salient) perspective at retrieval. What is produced at retrieval is oriented toward that perspective at the expense of other information that might be available. The lower total recall of individuals with low WMS implies that attention to the perspective makes demands on processing to the extent that fewer products of processing are produced or stored. Adopting an immediately (recently) available perspective may be a mechanism that compensates for the constraints of a limited working memory capacity. However advantageous such compensation may be for some retrieval, it takes its toll on overall recall. Information that might have been retrieved may be sacrificed in favor of information recalled under the new perspective. Apparent improved recall of ideas is accomplished by the omission of information that had been effectively retrieved on the first recall trial. It may be noted that these circumstances are not unlike those present in classroom test situations where students study from one perspective (e.g., they may study assumptions underlying a theory) but are required to answer questions from another perspective (e.g., they are tested on the methodology associated with the theory). If the pattern described above for our subjects is characteristic, the answers of the lower WMS students, are likely to be rated as “lacking breadth.” Although this study was not designed to directly test the encoding-specificity principle (Tulving & Pearlstone 1966), the overall findings support the hypothesis that accessing available knowledge depends upon provisions that heighten the saliency of ideas to be retrieved according to available unifying encodings.

REFERENCES Atkinson, R. C. & R. M. Shiffrin. (1968). “Human memory: A proposed system and its control processes.” Pp. 89-195 in Thr psychology of &zr~~irtgCIJI~ motivation: A~ZIUJZC~S in resenrch and theory (Vol. 2), edited by K. Spence. New York: Academic Press. Baddeley, A. (1986). Working memory. Oxford: Clarendon Press. Cronbach, L. J. & R. E. Snow. (1977). Aptitudes and imstructional methods: A hundhookfor research on interactions. New York: Halsted, Division of John Wiley & Sons, Inc. Daneman, M. & I’. S. Carpenter. (1980). “Individual differences in working memory and reading.” Iournul of Verbal Leurnirzg and Verbul Behmior, 19, 450-466. (1983). “Individual differences in integrating information between and within sentences.” IourJzal of Experimental Psycho/ogy: Leurrring, Memory and Cognition, 9, 561-584. Dixon, I’., J. LeFevre, & L. C. Twilley. (1988) “Word knowledge and working memory as predictors of reading skill.” Jourm/ ofEducnfiom/ Psychology, 80,465472.

WORKING MEMORY SPAN

231

Just, M. A. & I’. A. Carpenter. (1992). “A capacity theory of comprehension: Individual differences in working memory.“ Psychological Review, 99,122-149. Lee-Sammons, W. H. & P. Whitney. (1991). “Reading perspectives and memory for text: An individual differences analysis.” Journal of Experimental Psychology: Learning, Memoy 6 Cognition, 27,1074-1081. MacDonald, M., M. A. Just, & P. A. Carpenter. (1992). “Working memory constraints on the processing of syntactic ambiguity.” Cognitive Psychology, 24,56-98. Mason, M. E. J. &J. A. Miller. (1983). “Working memory and individual differences in comprehension and memory of text.” Journal of Educational Psychology, 75,314-3X3. Perfetti, C. A. & S. R. Goldman. (1976). “Discourse memory and reading comprehension skill.” Journal of Verbal Learning and Verbal Behavior, 14,3342. Pichert, J. W. & R. C. Anderson. (1977). “Taking different perspectives on a story.” Journal of Educational Psychology, 69,309-315. Reynolds, R. E. (1992). “Selective attention and prose learning: Theoretical and empirical research.” Educational Psychology Review, 4,345-391 Sharkey, N. E. & D. C. Mitchell. (1985). “Word recognition in a functional context: The use of scripts in reading.” Journal of Memory and Language, 24,253-270. Thurstone, L. L. & T. E. Jeffrey. (1956). Flags: A test of spatial thinking. Chicago, Il.: Industrial Relations Center. Tirre, W. C. & C. M. Pena. (1992). “Investigation of functional working memory in the reading span test.” Journal of Educational Psychology, 84,462472 Tulving E. & Z. Pearlstone. (1966). “Availability versus accessibility of information in memory for words.” Journal of Verbal Learning and Verbal Behavior, 5, 381-391. Turner, T. L. & R. W. Engle. (1989). “Is working memory capacity task dependent?” Journal of Memory and Language, 28,127-154.