RELATED LITERATURES WITH APPROPRIATE METHODOLOGIES

Aptitude-by-Treatment Interactions

Although the literature on learning styles per se has paid scarce attention to the need for group-by-treatment interactions, there has been a clear recognition of the importance of such interactions within an older educational psychology literature, going back to Cronbach's (1957) appeal for research to uncover interactions between aptitude and aspects of the instructional context (termed treatments). Although the validity of aptitude-by-treatment interactions (ATIs) is a separate issue from the validity of learning-style measures, which is the primary focus of the current article, we describe several ATIs so that the reader may gain an appreciation of a literature that recognizes the need to demonstrate the necessary interaction.

Initial attempts to demonstrate so-called ATIs were reviewed in a classic work by Cronbach and Snow (1977). According to Cronbach and Snow, these attempts were not highly successful because treatment durations were too brief, and aspects of the methodologies were inadequate. After that review, significant improvements were made in methodologies, with a number of studies examining treatments implemented in classroom settings for relatively long durations.

The kind of potential interaction that has received the most attention within the ATI tradition involves the degree to which the teaching approach provides ample structure or guidance for the learner. The primary hypothesis that has stimulated much of the work in this area is the idea that students with high ability tend to fare better in less structured learning environments than in highly structured learning environments. By contrast, students with low ability are hypothesized to fare better with instruction that is highly structured and provides explicit guidance than with instruction that is less structured and provides little guidance (see, e.g., Snow, 1977). A variant of this theme that also sparked interest is the idea that highly structured situations might reduce performance differences between students with high and low abilities (Freebody & Tirre, 1985). As detailed in the next paragraph, two key difficulties in evaluating this hypothesis are as follows: (a) The implementation of instructional methods that differ in structure (guidance) has been quite variable, and (b) the measures used to assess student abilities have varied considerably.

Freebody and Tirre (1985) reported an ATI in line with the above hypothesis that involved two competing reading-instruction approaches. One approach, the Matteson program (see Schlenker, 1978), provides a list of behavioral objectives in major reading-skill areas (e.g., word recognition, vocabulary development, literal and interpretative comprehension) combined with individualized learning packages that cover these areas, following precisely defined sequences. The other approach, the Scott Foresman (1972) program, is not strictly sequenced and monitored. Instead, the emphasis is on frequent discussions focusing on the literal and inferential aspects of discourse. This approach is assumed to place a greater burden on the student for acquiring specific reading skills (see Freebody & Tirre, 1985).

All of the sixth-grade students in a large school district who had been in one of the two reading programs for 2 years or longer served as subjects (N = 180, nearly equally distributed across reading programs). Their aptitudes were assessed with a standardized test that included nonverbal and verbal measures of ability. The outcome measure was the reading test score achieved at the conclusion of the sixth-grade year. Multiple regression analyses produced a significant ATI. The interpretation of the interaction was based on predicted outcomes (from the regression equations) for particular low-ability values and particular high-ability values. These predicted outcomes indeed showed that students with low ability would generally perform better on the structured reading program (Matteson) than on the less structured reading program (Scott Foresman). The reverse would be predicted for the students with high ability: better performance on the less structured than on the more structured reading instruction method. Although suggestive, these data do not establish that students at a particular ability level (either low or high) fared significantly better (in terms of reading outcomes) as a function of the reading program in which the students were enrolled.

Additional direct support for the idea that learning outcomes for students with high and low abilities might reverse with a greater degree of structure embedded in instruction was reported in the domain of elementary school mathematics (Cramer, Post, & Behr, 1989). Fourth graders being taught fractions were given four lessons (in six 40-minute class periods) on completing rational numbers tasks that involved shading a particular fractional area (two thirds) of different kinds of visual figures (e.g., a rectangle divided into three columns). In the high-structured condition, instruction was teacher centered with little student choice. The teacher paced through each example in large-group lecture fashion. In the low-structured condition, the teacher provided an initial introduction to the problems and then students worked through examples at their own pace. The materials involved leading questions to guide the learner to discovery of the key concepts. Both instructional conditions used identical examples, and both contained a 10-minute practice phase that completed each 40-minute class period. Students in the higher and lower ranges of cognitive restructuring ability, as measured by the Group Embedded Figures test (see Witkin & Goodenough, 1981), were assigned to each instructional condition. At the conclusion of the lessons, the students completed a final test containing problems (rational numbers tasks) of the type taught in the lessons. For the more difficult problems—those requiring physical restructuring of the diagrams—a crossover interaction between ability and the degree of instructional structure emerged. The students with high ability performed better following low- than high-structured instruction; by contrast, students with low ability performed better following high- than low-structured instruction. Particularly notable is that the students with low ability outscored the students with high ability (at least nominally) after both received the more highly structured instruction. This pattern thus provides evidence that learning is optimized when students with low ability are provided with structured instruction and students with high ability are provided with less structured instruction.

However, other studies that examined different content domains and used different assessment instruments did not always support the idea that high-ability students are better off with less structured instruction, whereas low-ability students profit more from higher-structured instruction. In Janicki and Peterson (1981), 117 grade school students completed a 2-week fractions unit in a “direct” instructional fashion (which involved homework assignments that students completed in class on their own) or in a less structured fashion (this involved mixed-ability four-student group seatwork with choice of homework or math games). Aptitude, as determined by a composite measure that included Ravens Progressive Matrices, did not interact with instructional method.

Greene (1980) similarly failed to find an interaction when fifth and sixth graders with high and low ability (as determined by Lorge-Thorndike verbal and nonverbal tests) were given high-structured instruction (specified sequence of workbook assignments and performance standards) or low-structured instruction (choice and pacing of which exercises to do in the workbook) on a letter-series task. The letter-series task was chosen to reflect general problem-solving goals in education. The basic result was that the students with higher ability performed better than the students with lower ability regardless of instruction.

In a well-conducted experiment, Peterson, Janicki, and Swing (1980, Study 2) manipulated instruction for a 2-week ninth-grade social studies unit across six classes (146 students). Two teachers taught each of three classes with one of three teaching methods. One teaching method was a standard lecture-recitation approach. In the second method, termed inquiry, students researched a historical question using primary sources. The third method, public issues discussion, required students to support a position on a current public issue using primary material. Aptitude was defined as verbal ability. The outcome measure was a test that included multiple-choice questions on historical facts and short essay questions requiring integration and evaluation of material. Critically, the test targeted readings and content common to all three instructional approaches. In line with the previous findings, there was no interaction between teaching method and ability for the essay performances, with students with higher ability performing better on the essay questions in general.

It is interesting to note that for the multiple-choice questions, there was a significant ATI such that students with high ability performed better with the lecture-recitation teaching method than with the inquiry or public issues discussion methods, whereas students with low ability performed better when receiving the inquiry or public issues methods than with the lecture-recitation method. This pattern would appear to counter the main hypothesis being considered in reviewing this body of ATI work, because the inquiry and public discussion methods encouraged learner self-direction (less structure). However, Peterson et al. (1980) offered an interpretation based on the underlying cognitive demands placed on the students by the different instructional methods. They suggested that the lecture-recitation approach implemented in the study placed a heavier burden on students' cognitive skills than did the other approaches. Specifically, students had to comprehend and attend to the lectures, take careful notes, and memorize target information. The idea is that students with high ability would have the requisite skills to accomplish these challenges. Of course, this interpretation does not clarify why the students with high ability would fare less well with the other instructional methods, relative to the lecture-recitation method.

One study activity that appears to be sensitive to individual ability differences is concept mapping (creation of diagrams that show the relationship among concepts), with students with low verbal ability profiting more from concept maps (in a chemistry learning activity) than students with high verbal ability (Stensvold & Wilson, 1990). Not surprisingly, in most studies the students with higher ability outperformed the students with lower ability in both instructional conditions.

However, complete crossovers have recently been reported with embedded-question techniques for learning from textbook chapters. In Callender and McDaniel (2007), the ability of interest was the degree to which learners can construct a coherent representation of presented content (either through text or lectures). Poor structure builders are assumed to perform relatively poorly at constructing a coherent representation of connected discourse that is either read or spoken (Gernsbacher, 1990). Such comprehenders appear to construct too many substructures to accommodate incoming information, rather than constructing a unified integrated representation of the target material. By contrast, good structure builders are able to extract coherent, well-organized mental representation of the text. Accordingly, Callender and McDaniel reasoned that embedding questions into a textbook chapter would orient poor structure builders to anchoring information around which to build a coherent representation and therefore improve learning for students at this level of comprehension ability. Embedded questions might be superfluous for good structure builders, however, because they are already able to construct coherent representations.

To test these predictions, Callender and McDaniel (2007) had college-age subjects read a chapter from an introductory psychology textbook with or without embedded questions. Afterward, the subjects were given a multiple-choice test consisting of questions targeting the information featured by the embedded questions and questions on information not targeted by the embedded questions. For poor structure builders, embedded questions significantly improved performance on target questions (relative to reading without embedded questions) but not performance on nontarget questions. Good structure builders did not profit from embedded questions, and indeed their performance for nontarget information was better without embedded questions. Note that these patterns could be considered evidence for the general notion that more guided study activities are preferable for comprehenders of lower ability, whereas less guided presentations (no embedded questions) are preferred for comprehenders of higher ability. These patterns clearly require replication, as only one chapter was considered and the subjects were in a laboratory experiment and not an actual course. Yet, this finding illustrates the potential fruitfulness of attempting to link more specific cognitive processing abilities to instructional techniques designed to dovetail with those abilities.

In summary, ATIs evidently do occur, but it has not been easy to determine exactly when they occur. This diversity of outcomes is perhaps not surprising given that available studies vary on a number of potentially critical dimensions, including target content, particular implementations of variations in instructional structure, assessments used to index ability, and the kinds of criterial (outcome) tests used. In some studies, the ATIs can be reported for one type of criterial measure but not another (e.g., see Cramer et al., 1989; Peterson, 1979; Peterson et al., 1980). At best, then, the ATI literature provides a mixed picture. A few studies are consistent with the idea that structured instruction produces better learning outcomes for students of lower ability (relative to less structured instruction), whereas less structured instruction produces better learning outcomes for students with higher abilities (relative to structured instruction). But other studies either did not obtain significant ATIs involving general ability and the degree of structure in instruction or in some cases indicated that students with lower ability fared worse with structured instruction than with less structured instruction. The greater coherence of the literature assessing structure building suggests that a more fine-grained approach that focuses on individual differences in underlying cognitive processes, rather than general aptitudes, and implements instructional methods that target those processes may be more fruitful in producing robust interactions between learner ability and learner-directed activities.