The effect of formal education, as opposed to chronological age, on intelligence development has suffered from inadequate empirical investigation. Most studies of this issue have relied on natural variation in exposure to school among children of the same age, thus confounding differences in schooling with differences in other intelligence-related variables. This difficulty can be overcome by a quasi-experimental paradigm involving comparison between children who differ in both chronological age and schooling. The present study applies this paradigm to the estimation of the independent effects of age and schooling in grades 5 and 6 on raw scores obtained on a variety of general ability tests. The sample included all students in Jerusalem's Hebrew-language, state-controlled elementary schools. The results unambiguously point to schooling as the major factor underlying the increase of intelligence test scores as a function of age and to the larger effect schooling has on verbal than nonverbal tests. These results contribute to our understanding of the causal model underlying intelligence development and call for reconsideration of the conceptual basis underlying the definition of deviation-IQ scores. Some implications of these results concerning the distinction between intelligence and scholastic achievement, the causal model underlying the development of "crystallized" and "fluid" abilities, and the notion of "culture-fair" tests are discussed.

The effect of formal education, as opposed to chronological age, on intelligence development has suffered from inadequate empirical investigation. Most studies of this issue have relied on natural variation in exposure to school among children of the same age, thus confounding differences in schooling with differences in other intelligence-related variables. This difficulty can be overcome by a quasi-experimental paradigm involving comparison between children who differ in both chronological age and schooling. The present study applies this paradigm to the estimation of the independent effects of age and schooling in grades 5 and 6 on raw scores obtained on a variety of general ability tests. The sample included all students in Jerusalem's Hebrew-language, state-controlled elementary schools. The results unambiguously point to schooling as the major factor underlying the increase of intelligence test scores as a function of age and to the larger effect schooling has on verbal than nonverbal tests. These results contribute to our understanding of the causal model underlying intelligence development and call for reconsideration of the conceptual basis underlying the definition of deviation-IQ scores. Some implications of these results concerning the distinction between intelligence and scholastic achievement, the causal model underlying the development of "crystallized" and "fluid" abilities, and the notion of "culture-fair" tests are discussed.

The independent influences of aging and schooling on the development of phonological awareness were assessed using a between-grades quasie.xperimental design. Both schooling (first grade) and aging (5-7 years) significantly improved children's performance on tests of phonemic segmentation, but the schooling effect was four times larger than the aging effect. The school-'"S effect »' «-y attributed to format reading instruction, whereas the aging effect probably reflects natural maturation and informal exposure to written language. These data support a strong mutual relation between reading acquisition and phonological awareness.Phonological awareness is the ability to recognize the internal phonemic structure of spoken words. It is usually assessed by testing the subjects' ability to isolate and manipulate individual phonemic segments in words.Although a child makes phonemic distinctions as soon as he or she can understand and produce speech, the ability to manipulate phonemic segments consciously develops only around the first grade. For example, Liberman, Shankweiler, Fischer, and Carter (1974) found that no prekindergarteners, only 17% of kindergarteners, but 70% of the first graders were able to parse words into phonemes.The significant improvement in phonological awareness in first graders may be primarily ascribed to one of two factors (which are not mutually exclusive):(1) cognitive-linguistic skills that mature at about the age of six, independent of formal reading instruction (Bradley & Bryant, 1983); or (2) learning to read in an alphabetic orthography (Berteison, Correspondence and reprint requests to

The universal nature of school attendance precludes the experimental investigation of the absolute effect of schooling on achievement. The available empirical evidence consists of the results of post hoc analyses of the within-grade-level relationship of students' achievement to the quality and quantity of schooling. This paper suggests a between-grade-levels quasi-experimental approach to the investigation of school's effect on achievement, involving the estimation of this effect by means of a regression discontinuity design. The paper presents the rationale underlying the suggested approach and demonstrates its application to the estimation of the effect of schooling at grade 2 on achievement in mathematics and reading comprehension.

For Israeli eighth-grade students of Asian-African origin, achievement decreases as a function of birth order in small families and increases as a function of birth order in large families. This finding cannot be accounted for by differences in developmental rate or size of birth intervals. It can be accounted for by considering the effect of external influences, such as schooling, on intellectual development.