Researchers across many fields have called for greater attention to heterogeneity of treatment effects--shifting focus from the average effect to variation in effects between different treatments, studies, or subgroups. True heterogeneity is important, but many reports of heterogeneity have proved to be false, non-replicable, or exaggerated. In…

The influence of individual difference variables on second language (L2) listening comprehension has been an area of research that has been gaining renewed attention in recent years. The current study investigated the effects of two cognitive variables, aptitude and metacognitive awareness, on 107 native-Korean, English as a foreign language…

The current study longitudinally examined the influence of aptitude on second language (L2) pronunciation development when 40 first-year Japanese university students engaged in practice activities inside and outside English-as-a-Foreign-Language classrooms over one academic year. Spontaneous speech samples were elicited at the beginning, middle,…

Test-taker characteristics (TTCs), or individual difference variables, are known to be a systematic source of variance in language test performance. Although previous research has documented the impact of a range of TTCs on second language (L2) learners' test performance, few of these studies have involved young learners. Given that young L2…

This study compares the performance of native speakers and adult second language (L2) learners on tasks tapping proficiency in grammar, vocabulary, and collocations. In addition, data were collected on several predictors of individual differences in linguistic attainment, including some related to language experience (print exposure, education,…

Knowing what skills underlie college success can allow students, teachers, and universities to identify and to help at-risk students. One skill that may underlie success across a variety of subject areas is structure building, the ability to create mental representations of narratives (Gernsbacher, Varner, & Faust, 1990). We tested if…

The purpose of this study was to investigate the four sources of self-efficacy in music performance and examine responses from the Music Performance Self-Efficacy Scale (MPSES). Participants (N = 290) were middle and high school music students from 10 schools in two regions of the United States. Questions included the following: (1) How much…

This inquiry analyzed the relationships between individual differences and gains made in oral proficiency of adult, second language learners of Spanish during one semester studying abroad. Oral proficiency was measured using a pre/post-SA Computerized Oral Proficiency Instrument (COPI, CAL, 2009). Gain scores were correlated with two cognitive…

This study investigated second language metalinguistic knowledge, or explicit knowledge about the second language, in English-speaking university-level learners of German and Spanish. The status of metalinguistic knowledge in relation to the individual difference variables of language-learning aptitude, working memory for language, and…

Relationships between cognitive and affective learner characteristics or "aptitudes" and mathematics achievement for sixth-graders in three instructional treatments in one school district were examined. Aptitude-treatment interaction (ATI) analyses were performed to test for differential prediction of achievement outcomes among treatments, using…

A test was given to 322 secondary students to develop a profile of mathematical ability based on four components: computation, pattern recognition, logical reasoning, and symbolic manipulation. These profiles were compared to mathematics test scores; the results verified hypotheses about individual differences in mental processes and knowledge…

The relationships between a diverse set of individual difference, demographic, and aptitude variables; and a set of student attitudes and behaviors pertinent to experiences in large lecture classes were examined. The sample was 4300 students enrolled in 33 lecture classes at a large university. The relationship between the set of individual…

A study examined the effects of two factors--learner ability and modifications of instruction through increased feedback and reduced size of instructional units--on the time required for learning and the retention of fourth-grade male students. While instructional modifications best predicted the time needed for learning, learner ability best…

To ascertain changes in cognitive correlates of learning as students advance through hierarchical instruction, 24 individual difference measures were obtained from 166 Navy trainees who had completed a computer-managed course in electricity and electronics. Principal component analysis and varimax rotation were computed for cognitive…

Student ability, involvement in the class, and classroom climate created by the instructor activities were examined as multiple and interactive predictors of course performance for 915 students in 74 sections of an undergraduate mathematics course. Climate was defined in two ways: (1) as individual perceptions and (2) as shared perceptions. Two…