Computers in Human Behavior 25 (2009) 371–380

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Computers in Human Behavior

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Semantic scaffolds in hypermedia learning environments

Wolfgang Schnotz *, Andrea HeißUniversity of Koblenz-Landau, Department of General and Educational Pschology, Thomas-Nast-Str. 44, Landau 76829, Germany

a r t i c l e i n f o

Keywords:Hypermedia learningSemantic scaffoldsPrior knowledge

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* Corresponding author. Tel.: +49 6341 990 234; faE-mail address: schnotz@uni-landau.de (W. Schno

a b s t r a c t

In knowledge acquisition from hypermedia, learners have to orient themselves in a non-linear informa-tion space, navigate in this space and build a knowledge structure from the information there. Researchon learning from hypermedia has focused primarily on enhancing orientation and navigation, with onlyminor attention on possibilities for supporting semantic processing. In a first experiment, 98 studentsfrom senior high school and university undergraduates learned about a complex subject matter eitherwithout or with semantic scaffolds, which were presented either in an obligatory (non-removable) orin an optional mode. High prior knowledge learners profited from adequately used semantic scaffolds,whereas low prior knowledge learners did not. In a second experiment, 53 senior high school studentsand university undergraduates received the learning material with semantic scaffolds presented eitherin an obligatory mode (but removable on demand) or in an optional mode. Learners with low priorknowledge performed better with optional presentation. Learners with high prior knowledge performedbetter with obligatory presentation, which allowed removing scaffolds on demand. Learners generallypreferred the optional presentation of learning scaffolds.

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1. Introduction

Educational research has repeatedly emphasized that learningis an active, constructive and goal-oriented process. Accordingly,learners are assumed to construct their own knowledge structuresand skills (cf. Shuell, 1988; Wittrock, 1989). In accordance with theactive and constructive nature of human learning, hypermediaseem to fit especially well as a supportive device for this process,because students are free to access various kinds of informationand can therefore adapt their information input to their informa-tion needs (Lawless & Brown, 1997; McKnight, Dillon, & Richard-son, 1993; Rouet & Levonen, 1996). It has also been assumedthat free criss-crossing through the information space of a hyper-medium would result in deeper comprehension and a higher cog-nitive flexibility of the learner than the traditionally linear patternsof information search (Spiro, Feltovich, Jacobson, & Coulson, 1991;Spiro & Jehng, 1990). However, learning with hypermedia requiresalso being oriented in a complex non-linear information space – anon-trivial task that often results in ‘being lost in hyperspace’(Conklin, 1987). In order to keep oriented, learners have to con-struct a mental representation of the information space besidestheir mental representation of the learning content (Calvi & DeBra, 1997; Dias & Sosua, 1997; Leutner, 1997; Scott & Schwartz,2007; Wenger & Payne, 1996). Accordingly, many studies havefocused on the effects of navigation aids designed to provide

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(hyper)spatial orientation and to make moving around in hyper-space easier (Dillon & Gabbard, 1998; Edwards & Hardman,1999; Foltz, 1996; Hill & Hannafin, 1997; McDonald & Stevenson,1996). Scheiter and Gerjets (2007) have discussed the multiplevariables involved in learning from hypermedia in a recent review.

Besides hyperspatial orientation, of course, the ultimate purposeof learning from hypermedia is construction of knowledge aboutthe learning content. In other words: learners can have not onlyspatial orientation problems but also semantic orientation prob-lems; learners can also have difficulties in constructing a coherentmental representation of the learning content. Because hypermedialearning requires both spatial orientation and semantic orientation,it can easily overload working memory. Accordingly, learners canlose sight of the learning aim, face difficulties in identifying themain topic and to recognize semantic macrostructures in the learn-ing material (Duchastel, 1990; Foss, 1989; Hammond, 1993). It fol-lows that learning from hypermedia can be supported not only byspatial orientation aids, but also by semantic scaffolds that supportthe learner’s comprehension and knowledge construction.

Whereas extensive research on semantic scaffolding has beenperformed with traditional linear materials, little research hasbeen done on semantic scaffolding with hypermedia (cf. Martens,Valcke, Poelmans, & Daal, 1996; McManus, 2000). In traditionallearning materials, semantic scaffolding have been provided byadvance organizers or epitomes (Ausubel, 1968; Mayer, 1978;Reigeluth & Stein, 1983), learning objectives (Duchastel, 1979;Hartley & Davies, 1976), problem-oriented questions (Rickards &Denner, 1978; Rothkopf, 1970; Rothkopf & Billington, 1979) and

372 W. Schnotz, A. Heiß / Computers in Human Behavior 25 (2009) 371–380

summarizers (van Dijk, 1980; van Dijk & Kintsch, 1983). Semanticscaffolds have been shown to support coherence formation by acti-vating the learner’s prior knowledge, by directing his/her cognitiveactivities, by elaborating the presented information and by formingsemantic macrostructures. Hardy, Jonen, Möller, and Stern (2006)have demonstrated that scaffolds can have a strong influence onlearning also within complex constructivist learning environ-ments. Given the difficulty of coherence formation with complexnon-linear learning material, one can expect that semanticscaffolds can also be important in hypermedia learning (Rouet &Levonen, 1996). The process and outcome of learning depend notonly on the structure and content of the learning material, how-ever, but also on the kind of learning activities performed by thelearner. Learning from hypermedia can only be effective to theextent that learners make adequate use of it, and the same mightapply also to the use of semantic scaffolds in hypermedia learning(Azevedo & Cromley, 2004; Chen & Rada, 1996; Nelson & Palumbo,1992).

This article aims at investigating whether knowledge acquisi-tion from hypermedia can be enhanced with semantic scaffolds,if these scaffolds are adequately used, and how these scaffoldsshould be presented in order to make learning from hypermediamore effective. First, we will analyze how the effectiveness of scaf-folds is constrained by the learner’s prior knowledge and cognitiveprocessing capacity; we will demonstrate that these constraintsresult in specific dilemmas in designing hypermedia. Second, wewill specify our research questions and derive correspondinghypotheses. Third, we will present and discuss the results of twoexperiments that aimed at testing these hypotheses. Finally, wewill draw practical conclusions regarding the use of semantic scaf-folds in hypermedia learning environments.

2. Constraints on the effectiveness of semantic scaffolds onlearning

Semantic scaffolds do not improve learning directly. Instead,they trigger learning-relevant cognitive activities, which finallyresult in higher learning under specific conditions. Factors influ-encing the effectiveness of scaffolds include the learner’s priorknowledge, his/her individual preferences or strategies as well asthe way these scaffolds are presented. On the one hand, semanticscaffolds can be expected to be beneficial for knowledge construc-tion from hypermedia as a result of deeper cognitive processing,elaborating information and of creating semantic macrostructures(Graesser, Millis, & Zwaan, 1997; Mautone & Mayer, 2001; Ozgun-gor & Guthrie, 2004; van Dijk & Kintsch, 1983). On the other hand,semantic scaffolds could also have negative effects on learning,because they require additional information processing, whichresults in additional cognitive load on working memory. Whetherthe effects have positive or negative effects on learning dependsto a large extent on the learner’s prior knowledge (Large, 1996;Niemiec, Sikorski, & Walberg, 1996).

Remember that learners do not only need to be oriented inhyperspace, but also to construct a coherent mental representationof the learning content. Both tasks can result in a considerable cog-nitive load, and processing semantic scaffolds can impose an addi-tional cognitive load on the learner’s working memory (Sweller,van Merriënboer, & Paas, 1998). If prior knowledge is low, scaffoldsmay challenge the individual’s processing capacities and interferewith comprehension and learning (cf. van den Broek, Tzeng,Risden, Trabasso, & Basche, 2001). If learners possess higher priorknowledge, they need smaller amounts of working memory capac-ity to cope with the orientation and comprehension task and, thus,are more likely to have further working memory capacity availablethan learners with lower prior knowledge. It follows that learners

with higher prior knowledge are more likely to benefit fromsemantic scaffolds than learners with lower prior knowledge. Thesituation might change if individuals have so much expertise thatthey do not need scaffolds at all, because in this case a so-calledexpertise reversal effect could occur: an instructional treatmentthat is effective for novices becomes ineffective for more knowl-edgeable learners, because the learners are required to processunneeded help (Kalyuga, Chandler, & Sweller, 2000; Kalyuga &Sweller, 2004).

Presenting semantic scaffolds to the right learners in the correctway is obviously not a trivial task in the design of hypermedialearning environments, because multiple constraints have to betaken into account. In the sections below, we will analyze threemajor constraints and will refer to these constraints as the Mat-thew’s problem, the problem of two conflicting errors, and theproblem of conflicting aims.

2.1. The Matthew’s problem: the rich will become richer

As the effectiveness of scaffolds depends highly on the learner’sprior knowledge, one frequently faces the following dilemma:although the poor learners need the scaffolds more than the goodlearner, the good learners profit more from them than the poorlearners (Shin, Schallert, & Savenye, 1994). This corresponds tothe well-known Matthew’s principle, namely that the rich willbecome even richer. In the field of instruction and learning, thisturns out to be a problem, because a group of learners can becomemore and more heterogeneous, when the good learners becomemore advanced whereas the poor learners fall further behind(Bickel & Howley, 2000). This raises the question whether oneshould provide scaffolds at all and, if yes, under which conditionsone should do so.

2.2. The problem of avoiding two kinds of error

As some learners do not need scaffolds, whereas other learnerscan be overwhelmed by them, the problem arises how two possi-ble errors can be avoided, which we will call (in analogy to infer-ence statistics) the alpha-error and the beta-error. If we assumethat there is a correct null-hypothesis stating that the learner doesnot need scaffolds, then the alpha-error would occur whenunneeded scaffolds are provided to the learner, because these scaf-folds only detract the learner’s cognitive capacity away from thelearning content. The alpha-error is frequently made by designersof multimedia learning environments, when they include as muchtechnical features as possible in order to ‘help’ the learner. Thebeta-error, on the contrary, would occur when needed scaffoldsare not provided. This error is frequently made by learners them-selves who due to an illusion of knowing overestimate their knowl-edge and think by mistake that they would not need scaffolds anymore (Glenberg, Wilkinson, & Epstein, 1982). Accordingly, thedevelopment of learning environments includes the followingdilemma: on the one hand, the less scaffolds are provided to thelearner, the lower is the danger of providing unneeded help. In thiscase, the alpha-error decreases, whereas the beta-error increases.On the other hand, the more scaffolds are provided to the learner,the lower is the danger of keeping back necessary scaffolds. In thiscase, the beta-error decreases, whereas the alpha-error increases.

Both the alpha-error and the beta-error can be manipulated bythe way in which learning scaffolds are presented. More specifi-cally, the two kinds of errors depend on the extent to which thepresentation and use of learning scaffolds is subject to self-directedlearning and how far the presentation is controlled by the learningsystem. The alpha-error (i.e., presenting unneeded scaffolds) canbe avoided by presenting scaffolds in an optional mode. In thiscase, it is the learner who decides whether he/she wants to use

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scaffolds or not. Thereby, he/she can avoid receiving unneededhelp. However, learners often ignore scaffolds or use them onlyto a very minor extent, which increases the likelihood of thebeta-error (i.e., not presenting or not using necessary scaffolds).The beta-error can be avoided by presenting learning scaffolds inan obligatory mode. In this case, it is not the learner, but the hyper-media learning system, which decides when scaffolds are to bepresented. In this way, one can act against the learner’s illusionthat the scaffolds are unnecessary, although he/she would in factneed them. Thus, the question arises, whether semantic scaffoldsshould be presented in an optional mode or in an obligatory mode.

2.3. The problem of conflicting aims

Teachers and learners evaluate learning environments frequentlyfrom different perspectives. For example, it is possible that teachersfocus primarily on learning outcomes, whereas learners, althoughinterested in the results of their learning as well, are also interestedin an agreeable or pleasurable learning situation. Learners’ prefer-ences do not necessarily correspond to what would be required forhigh learning efficiency. In computer-based learning, students usu-ally prefer to have a high amount of control of their own learning,although learner control does often not result in better learning thansystem control (Hasler, Kersten, & Sweller, 2007; Jonassen, 1986;Large, 1996; Steinberg, 1989). Nevertheless, these preferences arehighly important for self-directed learning, when the learner decideshow deeply he/she will process different parts of the learning con-tent and to what extent available learning scaffolds are used.Whereas teachers can prefer presenting scaffolds in a mode that willbe highly effective for learning, students can prefer presenting scaf-folds in a mode that is more pleasant to use (or which appears to beeffective for learning regardless of its real efficiency). Thus, the ques-tion arises which mode of presenting semantic scaffolds is mostacceptable for learners in self-directed learning.

3. Research questions and hypotheses

Our first research question was whether one should providesemantic scaffolds and (if yes) when one should provide them.We assumed that learners with high prior knowledge use theircognitive capacities more efficiently and, thus, are more likely tohave sufficient resources for effective processing of semantic scaf-folds than learners with low prior knowledge. It follows that ifindividuals engage in using these scaffolds adequately, learnerswith high prior knowledge will benefit more from semantic scaf-folds than learners with low prior knowledge.

The second research question was when semantic scaffoldsshould be presented in an optional mode and when they shouldbe presented in an obligatory mode. According to our previousanalysis, learners with low prior knowledge were expected to bemore prone to an alpha error – an error that can be avoided byoptional presentation of scaffolds – than learners with high priorknowledge. Learners with high prior knowledge were expected tobe more prone to a beta error – an error that can be avoided byobligatory presentation of scaffolds – than low prior knowledgelearners. Accordingly, we assumed that low prior knowledge learn-ers would benefit more likely from optional presentation of scaf-folds than from obligatory presentation compared to high priorknowledge learners. On the other hand, we assumed that highprior knowledge learners would benefit more likely from obliga-tory presentation of scaffolds than from optional presentationcompared to low prior knowledge learners.

The third research question was which mode of presenting scaf-folds is preferred by the learners. If learners would consider thealpha error and the beta error as equally important, their tendency

to prefer optional scaffolds should equal their tendency to preferobligatory scaffolds. Various studies on learning from hypermediahave shown, however, that individuals prefer a high amount oflearner control regardless of their prior knowledge (Large, 1996;Steinberg, 1989). We therefore assumed that learners prefer tohave more control rather than less control and will therefore preferthe optional mode to the obligatory mode of presenting scaffolds.

4. Experiment 1

4.1. Method

4.1.1. Participants and learning materialParticipants of this study were 98 students. In order to avoid too

much homogeneity in prior knowledge, we invited not only uni-versity students, but also students from public schools to join thestudy. The average age was 20.9 years (SD = 4.3) with a range from16 to 35 years. More specifically, 46 participants were 12-gradersfrom German gymnasiums (corresponding to senior high school;15 female); 52 participants were university students from the fieldof educational science and psychology in their first semesters (36female). The different proportion of males and females resultedfrom recruitment and from systematically different gender per-centages in educational science and psychology. However, as ouranalysis revealed, there were no significant differences betweenmales and females with regard to prior knowledge and learning re-sults. As the large majority of the gymnasium 12-graders in Ger-many are qualified for university studies in the following year,we had no reason to consider these groups as fundamentally differ-ent except for some study-related differences in prior knowledge.All learners were paid 10 Euros for their participation.

The learning material was part of a hypertext on attribution andsocial cognition with the main topics: 1. attribution, 2. social cog-nition of teachers, 3. social cognition of learners, 4. pygmalioneffects, 5. attribution training programs. The experimental learningsession focused only on the attribution part, which was sub-orga-nized into 2–4 hierarchical levels with a total number of 22 nodesand 3785 words. Fig. 1 presents a screenshot from the learningenvironment as an example of the graphical display. Studentscould navigate between the nodes of the text either through amenu-bar at the left side of the screen (including a hierarchicallyorganized list of main topics and their semantically related subtop-ics as shown in Fig. 1), through hot words within the text (rangingfrom 2 to 11 per screen page) and through a backwards button.Participants in two out of three groups received also semantic scaf-folds including an epitome as a pre-organizer, learning objectivesand problem-oriented questions before learning. These semanticscaffolds are presented in Appendix. After learning, participantsreceived a summary of about 400 words as a post-organizer. Dur-ing the course of learning, they had access to these semantic scaf-folds at any time via links on the top of the screen.

4.2. Procedure

In the pre-test phase, participants were checked for their learn-ing-relevant prior knowledge. None of them had already anyspecific prior knowledge about the actual learning content (‘attri-bution’). However, participants had different amounts of priorknowledge about related psychological concepts, which could beconsidered as learning-relevant. This learning-relevant, content-related prior knowledge was tested through a scale of 15 multiplechoice questions with an internal consistency of a = .70. The totalgroup of participants was subdivided by a median split into agroup of 48 learners with lower learning-relevant prior knowledge(which could also be considered as less advanced learners) anda group of 50 learners with higher learning-relevant prior

Fig. 1. Example of a screenshot of the learning environment with a navigation list on the left hand of the screen. The main topic ‘attribution’ is unfolded into hierarchicallyorganized sub-topics with two to four levels. The three links on the top of the screen provide access to the pre-organizer (‘Einführung’), learning objectives (‘Lernziele’) andlearning questions (‘Lernfragen’). The main frame of the screen includes the learning material (in this case the subtopic control cognition (‘1.2 Kontrollkognitionen’)) withhotwords providing access to further corresponding nodes. The white field in the upper right corner signals the remaining learning time to the individual.

374 W. Schnotz, A. Heiß / Computers in Human Behavior 25 (2009) 371–380

knowledge (which could also be considered as more advancedlearners). The low and the high prior knowledge learners wererandomly assigned to three groups with different scaffolding treat-ments in the following learning phase.

One group of 36 participants received semantic scaffolds in anobligatory mode. In this mode, the epitome, the learning objectivesand problem-oriented questions were presented in an obligatoryfashion before the learning material. The corresponding instructionpresented to these participants at the beginning of the learningsession and the epitome, the learning objectives and the prob-lem-oriented questions are shown in Appendix. Presentation timesof scaffolds were determined on the basis of a pilot study so thateach kind of scaffold could be read carefully even by slow readers.Presentation time was 82 s for the epitome, 106 s for the learningobjectives, and 52 s for the problem-oriented questions. After fin-ishing the last page, a summary of the learning material was pre-sented for 120 s. This kind of sequencing followed the generalresearch findings of the most effective timing of the correspondingscaffold. In addition, learners could access these scaffolds at anytime during the process of learning.

A second group of 30 participants received the same scaffolds inan optional mode. These learners were informed about the avail-ability of the scaffolds, but scaffolds were only presented whenrequired by the learner. The corresponding instruction presentedto these participants at the beginning of the learning session is alsoshown in Appendix. The epitome, the learning objectives and theproblem-oriented questions were the same as in the obligatorymode group. Learners could also access the scaffolds at any timeduring the process of learning. A third group of 32 participantsreceived the learning material without scaffolds. All participantswere informed that they would be examined for their knowledgeand comprehension after learning. Total learning time was45 min for all students, time on scaffolds not included. Participantsin the obligatory and the optional group were informed that they

could use the scaffolds as long as they liked (i.e. unlimited time,not included within the 45 min learning time).

Navigation activities and access to semantic scaffolds wereautomatically recorded in a log file. In the post-test phase, partic-ipants were tested for their learning results with a scale consistingof 25 questions, which required conceptual knowledge as well asdeeper comprehension and which had an internal consistencya = .63. The notion of knowledge and comprehension that servedas a basis for creating these questions, followed the taxonomy ofcognitive educational objectives, suggested by Bloom, Englehart,Furst, Hill, and Krathwohl (1956). Accordingly, comprehensionwas tested via the learners’ abilities to draw inferences about whathas been learned. Finally, the participants were questioned in asemi-structured interview about the quality and comprehensibilityof the scaffolds and about their preferred mode of presenting thescaffolds.

4.3. Scoring

For each participant, the following data were collected. Priorknowledge was determined as the number of the correctly an-swered questions in the pre-test. There were only minor differ-ences in prior knowledge between the three treatment groups,which were not significant (F(2,95) = 2.16, ns). The log files wereanalyzed according to the sequencing of scaffolds and the individ-ual’s time on them. The number of correctly answered questions inthe post-test was determined as an indicator for learning. Further-more, the individual preference for the different presentationmodes of semantic scaffolds was determined for each participant.

4.4. Results

The means and standard deviations of learning results withinthe different treatment groups (obligatory scaffolds, optional scaf-

Table 1Means and standard deviations of learning results in three treatment groups(obligatory scaffolds, optional scaffolds and no scaffolds) of participants with highand with low prior knowledge.

Obligatoryscaffolds

Optionalscaffolds

No scaffolds

M SD n M SD n M SD n

High prior knowledge 18.6 2.8 21 17.2 3.1 13 17.8 3.8 16Low prior knowledge 14.9 3.0 15 14.8 3.3 17 16.0 3.0 16

Table 2Means and standard deviations of learning results of participants with high and withlow prior knowledge with adequate use of semantic scaffolds and with no adequateuse of semantic scaffolds.

Adequate use of scaffolds No adequate use of scaffolds

M SD n M SD n

High prior knowledge 18.8 2.7 27 17.0 3.5 23Low prior knowledge 14.8 3.1 22 15.5 3.2 26

Table 3Preferences for optional presentation, obligatory presentation and for no presentationof semantic scaffolds in the three treatment groups.

Preferencefor optionalpresentation

Preferencefor obligatorypresentation

Preferencefor nopresentation

Total

Optionalpresentation

28 1 2 31

Obligatorypresentation

23 10 2 35

No presentationof scaffolds

25 6 1 32

Total 76 17 5 98

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folds and no scaffolds) of participants with high prior knowledgeand those with low prior knowledge are presented in Table 1. Wehad assumed that if individuals use semantic scaffolds correctly,learners with high prior knowledge will benefit more fromsemantic scaffolds than learners with low prior knowledge, Thus,we distinguished based on log file analyses in the optional scaf-folds group whether participants had used the scaffolds ade-quately. Usage of scaffolds was defined as adequate, if thelearner accessed the epitome, the learning objectives and theproblem-oriented questions before starting to work on the learn-ing material and if he/she accessed the summary after the learn-ing material as suggested. The participants in the optional groupwith adequate use of scaffolds were merged with the obligatorygroup, in which adequate use was enforced by the learning sys-tem, into a group of learners with adequate usage of scaffolds.Similarly, participants of the optional group without inadequateuse of scaffolds were merged with the no scaffolds group into agroup of learners without adequate usage of scaffolds. The corre-sponding means and standard deviations of learning results areshown in Table 2.

A 2 � 2 ANOVA with the factors adequate use of scaffolds (yes/no)and prior knowledge (low/high) showed no significant main effect ofadequate use of scaffolds (F(1,94) < 1, ns), but a significant maineffect of prior knowledge (F(1,94) = 19.2, MSE = 184.08, p < .001,g2

P = .17) and a significant interaction of prior knowledge x adequateuse of scaffolds (F(1,94) = 3.94, MSE = 37.76, p = .025, g2

P = .04). Toavoid the loss of information that results from dichotomizationof prior knowledge, we performed also a GLM (General LinearModel) analysis with the factor adequate use of scaffolds (yes/no)and with prior knowledge as covariate. This analysis revealed alsoa significant main effect of prior knowledge (F(1,94) = 26.7,MSE = 243.12, p < .001, g2

P = .22), no significant main effect of ade-quate use of scaffolds (F(1,94) = 1.83, ns), but a significant interac-tion prior knowledge x adequate use of scaffolds (F(1,94) = 2.92,MSE = 26.64, p = .045, g2

P = .03). Insofar, the results correspond toour assumption that if individuals adequately use semantic scaf-folds, learners with high prior knowledge will benefit more fromthese scaffolds than learners with low prior knowledge.

A 2 � 2 ANOVA with the factors mode of scaffolds presentation(obligatory/optional) and prior knowledge (low/high) revealed a sig-nificant main effect of prior knowledge (F(1,62) = 16.8,MSE = 154.66, p < .001, g2

P = .21), but no significant main effect ofmode of scaffolds presentation (F(1,62) < 1, ns) and, contrary toour expectation, no interaction (F(1,62) < 1, ns). The correspondingGLM analysis with the factor mode of scaffolds presentation (obliga-

tory/optional) and prior knowledge as a covariate revealed a signif-icant main effect of prior knowledge (F(1,62) = 18.9, MSE = 168.87,p < .001, g2

P = .23), but also no significant main effect of mode ofscaffolds presentation (F(1,62) < 1, ns) and no significant interactionprior knowledge x mode of scaffolds presentation (F(1,62) < 1, ns).Contrary to our expectation, there was no significant differencebetween low and high prior knowledge participants in learningwith regard to the mode of presenting semantic scaffolds. Learnerswith low prior knowledge did not perform better with optionalpresentation than with obligatory presentation. Learners with highprior knowledge performed slightly better with obligatory presen-tation than with optional presentation, but the difference did notreach statistical significance.

The interview data revealed that no participant expressed diffi-culties regarding the comprehensibility of the semantic scaffolds.The interview data were further analyzed with respect to the par-ticipants’ verbally expressed preference either for the optionalmode or for the obligatory mode of scaffolds presentation or forreceiving no semantic scaffolds at all. The result of this analysisis shown in Table 3. Although neither low nor high prior knowl-edge learners showed any different learning results with optionalor obligatory presentation, a majority of 76 out of 98 participantshad a clear preference for an optional presentation, no matterwhether they had received scaffolds or not before and no matterof how these scaffolds were presented to them. There was noessential difference between high and low prior knowledge learn-ers. As Table 3 indicates, the findings were basically the sameregardless of the kind of presentation mode the learners had expe-rienced before. A sign-test revealed a highly significant differencebetween the overall preference for the optional mode and the over-all preference for the obligatory mode (z = 6.01; p < .001). Accord-ing to our assumptions, learners preferred optional presentationmore than obligatory presentation of semantic scaffolds.

4.5. Discussion

Our results correspond to the assumption that learners withhigh prior knowledge profit more from adequately used semanticscaffolds than learners with lower prior knowledge. It seems thatlearners with higher prior knowledge cope better with the addi-tional processing demands of semantic scaffolds and thereforebenefit from them, whereas learners with low prior knowledgeare more likely to be cognitively overloaded, because they haveless working memory capacity available for additional processing.Semantic scaffolds such as epitomes, learning objectives, prob-lem-oriented questions and summaries can clearly promotelearning from hypermedia but only if learners have sufficientprior knowledge. This is in line with findings of Dillon and Gab-bard (1998), Gay (1986) and Jonassen and Grabinger (1990)who showed that learners with higher prior knowledge use exter-nal guidance more frequently and more efficiently than learnerswith lower prior knowledge. It also corresponds to the finding

1 The number of items was lower than in Study I because the inclusion ofapplication items made the average item in Study II more demanding and timeconsuming, which in turn suggested to omit items on the knowledge level that wereused in Study I.

Table 4Means and standard deviations of learning results of participants with high and withlow prior knowledge receiving obligatory (but removable) semantic scaffolds oroptional semantic scaffolds.

Obligatory mode (removable) Optional mode

M SD n M SD n

High prior knowledge 16.2 1.5 12 14.3 2.6 15Low prior knowledge 9.3 3.1 14 10.1 2.1 12

376 W. Schnotz, A. Heiß / Computers in Human Behavior 25 (2009) 371–380

that students with higher prior knowledge benefit more fromself-directed learning, whereas learners with lower prior knowl-edge benefit more from system-directed learning (Niemiecet al., 1996; Shin et al., 1994).

Regarding the mode of presenting scaffolds, our results supportthe assumption that learners prefer optional presentation of scaf-folds more than obligatory presentation. This is in line with otherstudies, which showed that individuals prefer a high amount oflearner control regardless of their prior knowledge (Jonassen,1986; Large, 1996; Steinberg, 1989).

Contrary to our expectation, high prior knowledge learners didnot benefit significantly more from obligatory scaffolds (comparedto optional ones) than low prior knowledge learners, and low priorknowledge learners did not benefit more from optional scaffolds(compared to obligatory ones) than high prior knowledge learners.Given that most participants in this study preferred optional pre-sentation of scaffolds, one reason why the obligatory presentationmode was not beneficial could be a reactionary effect by the learn-ers. The obligatory presentation of scaffolds was perhaps ‘tooobligatory’, because presentation was totally controlled by the sys-tem. The scaffolds appeared without demand, and they stayed for apredetermined amount of time on the screen, meanwhile theycould not be removed by the learner. This kind of system-directedappearance of scaffolds could not only have interfered with thelearners needs for content information. The ‘pushy’ kind of presen-tation might also have caused a negative attitude towards thelearning environment, which could have washed out any positiveeffects. We performed therefore a second study, which focusedonly on the mode of scaffolds presentation and used a more liberalkind of obligatory presentation that combined system control withlearner control.

5. Experiment 2

As hypermedia allow for a high amount of self-directed learningand as students prefer to be in control of their own learning ratherthan being exposed to system control, the rigid manner used in ourfirst study of presenting obligatory, temporarily non-removablesemantic scaffolds might have violated the learners’ expectationsof self-directed learning. For this reason, we used in our secondstudy a more flexible kind of obligatory scaffolds presentation withmore learner control. In the obligatory mode, semantic scaffoldsappeared without demand by system control, but could beremoved by the learner at any time, when he/she did no longerwant to use them. Insofar, there was more learner control withthe obligatory mode than in Study I, whereas the optional modewas the same as in the previous study. Because Study II focusedonly on differences between optional and (flexible) obligatorymode of presenting scaffolds, we did not include a group withoutscaffolds in this study.

We assumed again that low prior knowledge learners are morelikely to benefit from optional scaffolds compared to obligatoryones than high prior knowledge learners, because the former learn-ers can be overwhelmed by the additional information. We alsoassumed that high prior knowledge learners are more likely tobenefit from obligatory scaffolds (if these can be removed ondemand) compared to optional ones than low prior knowledgelearners, because the former learners can cope with additionalinformation, but are more likely to run the risk of an illusion ofknowing.

Similar to our first study, we assumed that learners prefer theoptional mode of presenting scaffolds rather than the obligatorymode of presenting scaffolds. We assumed that this preferencecan be found even when learners can remove the obligatory scaf-folds at any time and that it can be found regardless of which kindof presentation learners have experienced.

5.1. Method

5.1.1. Participants and learning materialParticipants of this study were 53 students. The average age was

18.3 years (SD = 1.3) with a range from 17 to 22 years. Twenty-three participants were 12-graders from German gymnasiums;30 participants were university students from the same domainsas in Study I 24 were males, 29 were females. Learners were alsopaid 10 Euros for their participation. The learning material wasthe same hypertext on attribution with the same possibilities ofnavigating as in Study I.

5.1.2. Procedure and scoringIn the pre-test phase, participants were again checked for their

prior knowledge. As in Study I, no participant had already any spe-cific prior knowledge about the learning content ‘Attribution’, butparticipants had different amounts of prior knowledge about re-lated psychological concepts, which were considered as learning-relevant. This learning-relevant prior knowledge was tested withthe same scale of multiple choice questions that was used in StudyI. The total group of participants was subdivided via median-splitinto a group of 26 learners with low prior knowledge and a groupof 27 learners with high prior knowledge. The low and the highprior knowledge learners were randomly assigned to two treat-ment groups. Both treatment groups received the same semanticscaffolds as in Study I, but under different conditions. Twenty-sixparticipants received the scaffolds in a removable obligatory mode:the scaffolds appeared automatically, but could be removed by thelearner at any time. With no intervention, the presentation timeswere the same as in Study I. Twenty-seven participants receivedthe scaffolds in an optional mode. There were only minimal differ-ences in prior knowledge between both treatment groups, whichwere far from significance (F(1,51) < 1, ns). The further instruction,time constraints and log file recording during the learning phase,the post-test phase and the scoring procedure were the same asin Study I. After the learning phase, a post-test with 20 itemswas administered that required comprehension as well as applica-tion of the learning content on briefly presented examples. The testrevealed an internal consistency of a = .72.1

5.2. Results

Means and standard deviations of learning results of partici-pants with high prior knowledge and with low prior knowledgeafter learning with obligatory scaffolds and with optional scaffoldsare shown in Table 4. A 2 � 2 ANOVA with the factors mode of scaf-folds presentation (obligatory/optional) and prior knowledge (low/high) revealed a highly significant main effect of prior knowledge(F(1,49) = 68.5, MSE = 406.54, p < .001, g2

P = .58), no main effect ofmode of scaffolds presentation (F(1,49) < 1, ns), but a significantinteraction for prior knowledge x mode of scaffolds presentation

Table 5Preferences for optional presentation, obligatory presentation and for no presentationof semantic scaffolds in the two treatment groups.

Preferencefor optionalpresentation

Preferencefor obligatorypresentation

Preferencefor nopresentation

Total

Optionalpresentation

24 3 0 27

Obligatorypresentation

22 3 0 25

Total 46 6 0 52

Note: Data from one participant in the obligatory presentation group were missing.

W. Schnotz, A. Heiß / Computers in Human Behavior 25 (2009) 371–380 377

(F(1,49) = 3.83, MSE = 22.71, p = .028, g2P = .07). To avoid the loss of

information resulting from dichotomization of prior knowledge,we performed also a GLM (General Linear Model) analysis withthe factors mode of scaffolds presentation (obligatory/optional) andprior knowledge as covariate. This analysis revealed a significantmain effect of prior knowledge (F(1,49) = 63.7, MSE = 393.24,p < .001, g2

P = .57), no significant main effect of mode of scaffoldspresentation (F(1,49) = 3.38, ns), but a significant interaction forprior knowledge x mode of scaffolds presentation (F(1,49) = 4.18,MSE = 25.77, p = .023, g2

P = .08). These results correspond to theassumption that for low prior knowledge learners optional seman-tic scaffolds are more likely to be beneficial (compared to obliga-tory scaffolds) than for high prior knowledge learners, whereasfor high prior knowledge learners, obligatory scaffolds are morelikely to be beneficial (compared to optional scaffolds) than forlow prior knowledge learners. Whereas the corresponding contrastdid not reach statistical significance within the group of low priorknowledge learners (and showed therefore only a tendency), highprior knowledge learners performed significantly better withobligatory scaffolds than with optional ones (t(23.3) = 2.29,p < .05).

The interview data were analyzed in the same way as in Exper-iment 1. No participant mentioned difficulties regarding the com-prehensibility of the semantic scaffolds. The data were alsoanalyzed with regard to the participants’ preference for theoptional mode or for the obligatory mode of presenting scaffoldsor for presenting no scaffolds. The result of this analysis is shownin Table 5. Like in Study I, a large majority of 46 out of 52 partici-pants (i.e. 88%) preferred an optional presentation. There was noessential difference between high and low prior knowledge learn-ers. The finding was the same regardless of the kind of presentationmode learners had experienced before. The different groups weretherefore combined. A sign-test revealed a highly significant differ-ence between the preference for the optional mode and the oblig-atory mode (z = 5.41; p < .001). Although a rather flexible version ofobligatory scaffolds was used, which could be removed at any time,the large majority of learners preferred the optional presentation.

5.3. Discussion

In contrast to the previous study, Experiment 2 used a moreflexible way of presenting obligatory semantic scaffolds. Thesescaffolds appeared without demand, but could be removed bythe learner at any time. Insofar, the learning environment in thesecond study allowed for a higher amount of learner control inthe obligatory mode than the environment used in the first study.This way of presenting semantic scaffolds might have been betteraligned with the learners’ concept of self-directed learning andhis/her corresponding expectations, especially as students preferto be in control of their own learning rather than being exposedto system control. Accordingly, we found indications that learnerswith low prior knowledge perform better with optional scaffoldsthan with obligatory ones, whereas learners with high prior knowl-

edge perform better with obligatory than with optional scaffolds –provided that the obligatory ones can be removed by the learnerwhenever he/she wants.

It seems that even if obligatory scaffolds are presented withmore learner control (when they are removable), low prior knowl-edge learners nevertheless benefit more from optional scaffoldsthan from obligatory ones. High prior knowledge learners seemto benefit more from obligatory scaffolds than from optional ones,if they can remove these scaffolds whenever they want. Theselearners might be able to cope with additional information, butare in danger of ignoring needed relevant scaffolds due to anillusion of knowing. Finally, our results indicate that learners preferoptional scaffolds more than obligatory ones, even when thesescaffolds can be removed at any time.

6. General discussion

Developing hypermedia learning environments and hyperme-dia learning are specific variants in a general framework of teach-ing and learning. Within this framework, the relation betweeninternal and external control of learning is a central issue, becausefinding an optimum balance between the two sides is a delicatetask (Reiser, 2004). Hypermedia seems to be highly attractive forteaching and learning, because they provide the possibility for ahigh amount of self-directed learning. Students are more likely toaccept a learning environment if it includes possibilities for learnercontrol, although self-directed learning frequently does not neces-sarily lead to better learning than system-directed learning (Jonas-sen, 1986; Large, 1996; Steinberg, 1989). The non-linearorganization of information in hypermedia is assumed to stimulateprocesses of mental construction, especially when new informa-tion needs to be elaborated with the help of prior knowledge(Cunningham, Duffy, & Knuth, 1993; Jonassen & Grabinger,1990). However, there are also individual differences to be takeninto account. Various studies suggest that students with higherprior knowledge are more likely to benefit from self-directed learn-ing in hypermedia environments, whereas students with lowerprior knowledge perform better in more system-directed learningenvironments (Dillon & Gabbard, 1998; Gay, 1986; Jonassen & Gra-binger, 1990; Niemiec et al., 1996; Shin et al., 1994).

These findings are not really surprising, because self-directedlearning always implies specific challenges. A student has to makedecisions about his/her learning, that is, to decide which informa-tion should be selected and how this information should besequenced. This task requires awareness of learning aims and ofthe specific learning conditions, which also includes meta-cogni-tive monitoring of one’s own knowledge and comprehension. Inlearning from hypermedia, the student needs also orientationabout the information space: he/she needs to know where to findwhich information and how to go there (Calvi & De Bra, 1997;Carmel, Crawford, & Chen, 1992; Marchionini, 1989). Learningfrom hypermedia is therefore a dual task: besides comprehensionof the subject matter, the learner has to construct a mental repre-sentation of the information space and he/she has to handle themedium. Both kinds of tasks require cognitive capacity, whichimposes cognitive load on working memory (Sweller et al.,1998). As an increase of prior knowledge reduces cognitive load,students with higher prior knowledge might face lower cognitiveload in hypermedia learning and therefore are more likely to copewith these specific requirements than students with lower priorknowledge.

Whereas most studies on learning with hypermedia focused onpossibilities to avoid hyperspatial orientation problems, the stud-ies described in this article focused on possibilities to avoid con-ceptual orientation problems with the help of semantic scaffolds

378 W. Schnotz, A. Heiß / Computers in Human Behavior 25 (2009) 371–380

such as epitomes, learning objectives, problem-oriented questionsand summaries (Duchastel, 1979; Hartley & Davies, 1976;Reigeluth & Stein, 1983; Rothkopf & Billington, 1979; van Dijk,1980). The use of semantic scaffolds can be a two-edged sword.On the one hand, scaffolds can activate students’ prior knowledge,focus their attention on relevant aspects of the learning task, servean orientation function for the knowledge to be constructed,encourage reflection about the subject matter and challenge theinterpretations made by the students (Davies & Linn, 2000; Hogan& Pressley, 1997; Pea, 2004; Reiser, 2004). On the other hand, thescaffolds require additional working memory capacity, whichcould overwhelm students with lower prior knowledge and there-fore result in poorer learning (Sweller, 2005; Sweller et al., 1998).

Using semantic scaffolds implies different problems. First, poorlearners need the semantic scaffolds more than good learners, butthe good learners profit more from these scaffolds than the poorones. Our results indicate that learners with high prior knowledgeprofit more from adequately using semantic scaffolds than learnerswith lower prior knowledge. Learners with higher prior knowledgemight be better able to cope with the additional processingdemands of semantic scaffolds, whereas learners with low priorknowledge perform better without these scaffolds, because pro-cessing scaffolds implies additional cognitive load, which couldoverwhelm these learners’ capacities. This corresponds to the find-ings of other studies, where learners with higher prior knowledgeused external guidance more frequently and more efficiently thanlearners with lower prior knowledge (Dillon & Gabbard, 1998; Gay,1986; Jonassen & Grabinger, 1990).

A second problem is how to avoid different kinds of errors. Oneerror is to provide unneeded help to the learner. This error can beminimized by presenting semantic scaffolds in an optional mode,because the learner can then decide him/herself, whether he/shewants to use the scaffolds or not. Another error is to keep backneeded scaffolds from the learner. This error can be minimizedby presenting semantic scaffolds in an obligatory mode, becausethe learner receives the scaffolds in any case. The obligatory modeof presenting semantic scaffolds avoids erroneous decisions of stu-dents who assume due to an overestimation of their own expertisethat they would need no scaffolds any more (Glenberg et al., 1982).A rigid obligatory mode of presentation, however, might violate thelearners’ expectations of self-directed learning. A more flexible var-iant of an obligatory presentation would allow for a higher amountof learner control, as the scaffolds can be removed at any time. Thisvariant might also be more acceptable for learners. We hadassumed that learners with lower prior knowledge are more likelyto receive scaffolds that overwhelm their cognitive capacities. Thiserror can be reduced by optional presentation of scaffolds. On theother hand, we had assumed that learners with higher prior knowl-edge are more likely to ignore scaffolds that they would need butdo not use due to an overestimation of their own expertise. Thiserror can be reduced by obligatory presentation of scaffolds.

Our findings indicate that learners with low prior knowledgeperform indeed better with optional presentation than with oblig-atory presentation of semantic scaffolds, whereas learners withhigh prior knowledge perform better with obligatory than withoptional presentation of scaffolds, when the scaffolds can beremoved by the learner at any time. Low prior knowledge learnersseem to benefit more from optional presentation of scaffolds. Highprior knowledge learners can obviously cope with additionaldemands, but are in danger of ignoring needed semantic scaffoldsdue to an illusion of knowing. Accordingly, they benefit more fromobligatory presentation of scaffolds, if the scaffolds can be removedon demand.

We found that learners prefer optional presentation of semanticscaffolds more than obligatory presentation, even when they couldremove the obligatory scaffolds at any time. This preference could

be found regardless of what kind of presentation they had experi-enced before. Students seem to prefer a high amount of learnercontrol regardless of their prior knowledge, even when the highamount of control does not result in better learning (Jonassen,1986; Large, 1996; Steinberg, 1989). The same preference couldalso be found in our studies with regard to the mode of presentingsemantic scaffolds.

To summarize, our results indicate that semantic scaffolds canenhance self-directed learning from hypermedia under specificconditions. Learners with higher prior knowledge can profit fromadequately used semantic scaffolds, whereas learners with toolow prior knowledge run the risk of being overloaded by the addi-tional processing of these scaffolds. The findings indicate that thereseems to be paradox of learning scaffolds, namely that providingmore help is not necessarily helpful for learning. At first sight, theyeven seem to suggest that one should abstain from using semanticscaffolds in hypermedia environments, because poor learnerswould need semantic scaffolds more than the good learners, butthe latter profit from these scaffolds, whereas poor learners areovercharged by additional information. However, this conclusionwould be too rash. Our findings indicate that hypermedia environ-ments can be overloaded with semantic scaffolds, at least from theperspective of learners at a lower level of expertise. Therefore,instead of renouncing learning scaffolds altogether, we would sug-gest that semantic scaffolds should not be presented too early (i.e.at a too low learner’s expertise) and not on a too large scale. In otherwords, the use of semantic scaffolds should be well aligned withthe individual’s zone of proximal development (Schnotz &Kürschner, 2007; Vygotski, 1963). Insofar, our findings are alsoconsistent with the idea of presenting information just-in-timeduring the acquisition of cognitive skills (Kester, Kirschner, vanMerriënboer, & Baumer, 2001).

If learners have lower prior knowledge, optional presentation ofsemantic scaffolds seems to be better than obligatory presentation,because an optional presentation allows the learner to retrieve scaf-folds on demand, whereas an obligatory presentation could easilyoverload the learner. If learners have higher prior knowledge, how-ever, an obligatory presentation of semantic scaffolds is clearly moreadequate, because an optional presentation of scaffolds can possiblyseduce learners with higher prior knowledge to abstain from usingscaffolds due to an illusion of knowing (Glenberg et al., 1982),although they would actually profit from these scaffolds. Semanticscaffolds presented in an obligatory mode should not contradictthe learners’ preferences. Instead, they should fit into the conceptof self-directed learning. Accordingly, the learner should be able toremove the scaffolds in the obligatory mode at any time.

With regard to the design of hypermedia learning environ-ments, our results suggest that one should not abstain from usingsemantic scaffolds, but one should abstain from overloading learn-ing environments with regard to the individuals’ zone of proximaldevelopment. Less can be more.

Acknowledgements

We gratefully acknowledge the support of Antje Eckhardt inrunning the experiments presented in this article. We also wantto thank three anonymous reviewers for the comments and sug-gestions based on a former version of this article.

Appendix A

A.1. General instruction of the obligatory mode (translated from German)

Before you start reading the chapter ‘Attribution’, you will bepresented some learning scaffolds, namely

W. Schnotz, A. Heiß / Computers in Human Behavior 25 (2009) 371–380 379

– an introduction,– information about learning objectives,– learning questions.

These scaffolds will appear and disappear on their own. You willhave sufficient time to read them carefully. During the learningsession, you have also access to these scaffolds at any time viathe corresponding buttons on the screen.

At the end of the learning session, you will receive a writtensummary of the chapter. You will also have sufficient time to readthis summary. The summary will then disappear on its own.

Please read all scaffolds carefully.In order to start with the learning session, click here: start learn-

ing session

A.2. General instruction of the optional mode (translated fromGerman)

Before you start reading the chapter ‘Attribution’, we would liketo give you some information about learning. Various studies haveshown that learning scaffolds such as an introduction, informationabout learning objectives and questions are useful for learning. Wehave prepared such learning scaffolds and we would like offeringthem to you.

– If you want to see the introduction, click here: show introduction.– If you want to see learning objectives, click here: show learning

objectives.– If you want to see learning questions, click here: show learning

questions.

During the learning session, you have also access to these scaf-folds at any time via the corresponding buttons on the screen.

Studies have also shown that it is useful for learning to have asummary of what has been read and learned before. You shoulduse this opportunity too. We will remind you to use the summaryagain by the end of the learning session.

In order to start with the learning session, click here: start learn-ing session.

A.4. Introduction (Epitome, translated from German)

Humans tend to look for explanations of events that happen tothem. In case of personally relevant events such as success or fail-ure, for example, they try to explain these events in a way thattakes into account the data, but also protects their self-esteem.Bad marks, for example, can be ‘explained’ by attributing them totoo high difficulty of tasks rather than to too low abilities. These‘explanations’ require frequently solving conflicts between empir-ical data and personal claims, which makes processing ratherdemanding. Finding explanations of personally relevant events isreferred to as ‘causal attribution’ or simply ‘attribution’ in psychol-ogy. Attributions can be classified according to different aspects as,for example, whether the cause is located within or outside theindividual, whether the cause is stable or variable or whether itcan be controlled by the individual or not.

A.5. Learning objectives (translated from German)

You should know after having studied this chapter,

– what the terms ‘cognition of control’ and ‘causal attributions’mean,

– how the assumed causes of success or failure perceived by anindividual can be classified,

– what the term ‘learned helplessness’ means,

– how causal attributions can be supportive for self-esteem,– how attributions are influenced by the learning content,– how attribution tendencies differ between hope for success and

fear of failure.

You should also unterstand,

– what causes individuals to attribute causes to the results of theiractivities,

– why individuals who assume to be in control of the events intheir environment differ from individuals who assume that theyare not,

– how learned helplessness can be generated,– how causal attributions can solve cognitive conflicts,– why high and low learning performance results in different

attributions depending on the subject matter of learning,– why motivation by hope for success and motivation by fear of

failure result in different patterns of causal attribution.

A.6. Learning questions (translated from German)

During the course of learning, you should try to answer the fol-lowing questions:

– Why does an individual’s feeling of having no control of him/herself and his/her environment have negative effects on his/her development?

– How could low learning performance be explained in a way thatprotects the individual’s self-esteem?

– How should learning environments be designed in order toweaken the possible relation between investment of effort dur-ing the process of learning and the danger of loosing one’s self-esteem in case of failure?

– Why is it important for teachers to know about their students’tendencies towards motivation by hope for success and motiva-tion by fear of failure?

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