Two Ways of Knowing

Socrates, the founder of the inductive method (Watson, 1978), was a master at analytical reasoning. Plato, his student, believed in the reality of abstract Forms perceivable only through "the mind's eye," and imperfectly represented in everyday life (Plato's Republic, Jowett trans., 1871/1944, p. 258). Aristotle, Plato's student, denied the Platonic Forms, and turned to biological classification in his search for truth. Like Plato, Aristotle believed that imagery was important, but he added the element of sequentiality: "we recall these images by ordering them in sequence, associating them with one another according to the principles of similarity, contrast, and contiguity" (cited in Wittrock, 1978, p. 61). The threads of analytical, sequential reasoning versus nonsequential, geometric visions of reality create a fascinating dialectic of differing world views throughout the history of psychology. Consider Locke's associationism, Pavlov's classical conditioning, Watson's behaviorism, Skinner's operant conditioning, and Bloom's taxonomy compared with Kant's a priori Anschauungen-"the spatial arrangement of objects given in perception" (Boring, 1950, p. 248); the gestalt psychologists-Wertheimer, Kohler, Koffka; Piaget's assessment of formal operational thought; and Guilford's structure-of-intellect model. Some of the greatest minds in psychology conveyed their ideas in analytical sequences of ideas, while others tried to communicate images and geometrical relationships. Is it possible that the clashes in conceptualization can be traced to differences in cerebral processing modes of the theorists?

In an attempt to answer that question, we turn to the field of neurophysiology. Well before the turn of the century, John Hughlings Jackson, a pioneer in brain research, hypothesized that the processing of visual information, perception, and visual imagery are all the province of the right cerebral hemisphere, whereas the processing of auditory information, verbal expression, and propositional thinking are the domain of the left hemisphere (Taylor, 1932/1958). It is interesting to note that Hughlings Jackson's formulation of a hierarchy of levels in the evolution of the nervous system, from simple to complex and from automatic to voluntary, was also pivotal in the development of Dabrowski's theory. Bogen (1969) asserted that the duality of the hemispheres is the basis for many other dualities throughout history-the yin and yang of human experience. He summarized the ways in which the two hemispheres have been described since the mid-nineteenth century: the "major" hemisphere characterized as expressive, linguistic, executive, symbolic, verbal, discrete, logical, analytic and propositional, and the "minor" hemisphere described as visual, visuospatial, kinesthetic, imaginative, perceptual, synthetic, preverbal, nonverbal, diffuse, and appositional.

The deduction that the right and left hemispheres specialize in different functions has been fairly well accepted in the last three decades. "The left cortical hemisphere...specializes somewhat in a propositional, analytic-sequential, time-oriented serial organization well adapted to learning and remembering verbal information" (Wittrock, 1978, p. 65), whereas "the processing of visual images, spatial relationships, face and pattern recognition, gesture, and proportion are seen to be specialized in the right hemisphere" (West, 1991, p. 14).

A converging body of evidence from unilaterally brain-damaged patients, from investigatings [sic] of normal people, and from split-brain research points to the conclusion that the left hemisphere is vastly superior and dominant to the right in linguistic processing, that it thinks logically, deductively, analytically, and sequentially, that its superiority derives from fundamental differences in the way it processes, decodes, encodes, and arranges information. The right hemisphere is superior and dominant to the left in visuospatial construction, in recording the literal properties of the physical world, in visualizing the relationships of objects in space, and probably, in reaching accurate conclusions in the absence of logical justification. (Levy, 1980, p. 253)

Benbow and her associates have found evidence that intellectually gifted students have enhanced right hemispheric functioning (Benbow, 1986; 1992; O'Boyle & Benbow, 1990). Referring to the work of Geschwind and Behan (1982), in which left-handedness and immune disorders were correlated with enhanced right-hemispheric development, Benbow (1986) found that "80% of mathematically and/or verbally extremely precocious students were left-handed, myopic, and/or had allergies" (p. 724). Summarizing two decades of research, Benbow (1992) reported:

For the chimeric face task, the right hemisphere was markedly more active than the left, especially at the temporal lobe, while for the average ability students the left hemisphere was somewhat more active. For the verbal task (noun/verb determination), the right hemisphere of the extremely precocious was somewhat more active with the opposite pattern found for the average ability subjects. These electrophysiological data corroborated the behavioral findings of O'Boyle and Benbow (1990a), and support their hypothesis of enhanced right hemisphere processing involvement being a correlate of intellectual precocity....

In this context, it is interesting to note that some of the characteristics that long have been found to describe intellectually talented students...are also thought to characterize the cognitive functions or contributions of the right hemisphere to problem-solving (e.g., see things holistically, deep comprehension, advanced moral reasoning, and humor)....The right hemisphere is thought to be better at dealing with novelty than the left hemisphere.

In summary, evidence is beginning to emerge indicating that the organization of cognitive functions within the left and right hemispheres in the intellectually precocious differs from that found for individuals with more average abilities. The intellectually precocious exhibit enhanced right hemispheric functioning. (p. 104)

However, not all researchers are in complete agreement with the localization of brain functions. For example, Gazzaniga (1985) holds that the left hemisphere, the seat of language processes for the majority of the population, controls general cognitive functioning. He has a modular view of brain organization, similar to Howard Gardner's (1983).

Clearly what is important is not so much where things are located, but that specific brain systems handle specific tasks. We begin to see that the brain has a modular nature, a point that comes out of all of the data.... That is, it is not important that the left brain does this or the right brain does that. But it is highly interesting that by studying patients with their cerebral hemispheres separated certain mental skills can be observed in isolation. It is a hugely significant point. (Gazzaniga, 1985, pp. 58-59)

It must be kept in mind that there is a complex interaction between the two hemispheres, particularly for higher level thought processes. Wittrock (1978) reminds us that "no dichotomy of function does justice to the sophistication and complexity of the human brain" (p. 66).

Alexander Luria (1973), a leading neuropsychologist, also questioned the localization of verbal functions in the left hemisphere and perceptual or nonverbal functions in the right hemisphere. Like Gazzaniga, he attributed greater cognitive power to the left hemisphere, perceiving it as the source of volitional control of behavior, with the right hemisphere responsible for subconscious, automatic processes not under volitional control. Luria distinguished between simultaneous (all-at-once) and successive (sequential) processing, but he placed successive processing in the fronto-temporal regions of the brain and simultaneous processing in the occipital-parietal region. Simultaneous processing is essential to the discovery of relationships between components and the integration of many stimuli at once, often with spatial overtones (Kaufman, 1984), while successive processing enables the serial ordering of information.

Das, Kirby and Jarman (1979) developed a successive-simultaneous battery based on Luria's theory and validated the model with several studies of children. The simultaneous/sequential distinction became the basis of one of the leading assessments of children's intelligence: The Kaufman Assessment Battery for Children (K-ABC) (Kaufman & Kaufman, 1983). A study of gifted young children (ages 4-6) conducted with the K-ABC (Hafenstein, 1986) found intellectual giftedness to be more strongly correlated with simultaneous than sequential processing, and highly gifted children were strong in both types of processing. Sequential processing was related to reading recognition and simultaneous processing with reading comprehension.

From a completely different perspective, Raymond Cattell (1963) proposed a two-factor theory of intelligence-fluid and crystallized abilities-based on factor analytic evidence of the structure among primary mental abilities. Fluid intelligence is general reasoning ability, particularly the process of perceiving relations in figural and spatial material, whereas crystallized intelligence is the product of acculturation-education, training and practice-such abilities as verbal and quantitative reasoning, sequential memory, vocabulary, and reading comprehension. "This kind of ability uses verbal mediation, sound inference, and sequential steps of logic in problem solving" (Harvey & Seeley, 1984, p. 76). Cattell (1963) proposed that fluid intelligence is physiologically determined, but his collaborator, Horn (1976), and many other researchers who accept the basic theory, (e.g., Snow, 1981; Thorndike, 1963), reject the implication that fluid abilities are innate. Cattell's theory of fluid and crystallized abilities strongly influenced Sternberg's (1985) triarchic theory of intelligence and became the basis of another major intelligence test: the Stanford-Binet Intelligence Scale, Revision IV (Thorndike, Hagen & Sattler, 1986).

Harvey and Seeley (1984) used Cattell's theory in their analysis of the abilities of youth in a juvenile detention center. Fifteen percent of the youth scored in the top third percentile on selected subtests of the WISC and WAIS, and the gifted offenders demonstrated higher fluid than crystallized abilities.

This pronounced elevation of the nonverbal areas of ability is evidenced among the gifted students in this study.... The fluid ability of these students had the greatest contribution to the gifted classification.... The traditional classroom situation appeared to have suppressed these students' high fluid abilities in the process of their learning of academic skills. (p. 77)

Fluid intelligence sounds very much like Luria's simultaneous factor and the visual-spatial abilities attributed to the right hemisphere. Crystallized intelligence seems to incorporate Luria's successive factor, and the linguistic competencies attributed to the left hemisphere. Regardless of their location in the brain, there appear to be two factors-two basic ways of knowing-that need to be taken into account in educating gifted children: spatial or fluid abilities and sequential or crystallized abilities. Hughlings Jackson (in Taylor, 1932/1958) proposed that the left hemispheric abilities are related to audition and that the right hemispheric abilities related to vision. Spatial and visual are often combined as a single factor: "spatial-visualization ability" (Lohman, 1989) and the connection between sequencing and audition has been established in studies of impaired auditory processing (Northern & Downs, 1994), and the development of reading skills (N. Jackson, in press). The eye is considered a "synthetic organ," since it mixes different wavelengths of light so that we perceive a single color, while the ear is an "analytical organ," since it analyzes different frequencies of sound waves so that we can detect the individual components (Carlson, 1995, pp. 171-172). Temporal (time-sequenced) information is processed auditorily and spatial information is processed visually.