Cerebral lateralization in bilinguals: Methodological issues

The literature on lateralization for language in bilinguals manifests two apparent contradictions. Some papers demonstrate differences in lateralization between bilinguals and monolinguals; others demonstrate none. In studies with exclusively bilingual subjects, some papers demonstrate differences between the lateralization for the two languages, while others demonstrate none. This paper discusses the range of methodological parameters which must be borne in mind when conducting or evaluating studies of lateralization for language in bilinguals. These include issues of subject selection, language and stimulus selection, testing procedures, data analysis, and interpretation of results.     

Lexical decision for open- and closed-class words: failure to replicate differential frequency sensitivity

Bradley and her colleagues (D. C. Bradley, Computational distinctions of vocabulary type, unpublished Ph.D. thesis, Massachusetts Institute of Technology, 1978D. C. Bradley, M. E. Garrett, &; E. B. Zurif, in D. Caplan (Ed.), Biological studies of mental processes, Cambridge, MA: MIT Press, 1980) have reported a marked difference in frequency sensitivity between open- and closed-class words on a lexical decision task. This effect was obtained with normal subjects, but not with Broca's aphasics. Their results have already influenced experimental and theoretical investigations of syntactic processing. However, in three lexical decision experiments with normal subjects, modeled on those of Bradley et al., we failed to find such a theoretically interesting difference between the two classes. Instead, both classes showed similar reaction time frequency sensitivity for word frequencies less than approximately 316/million (H. Kucera &; W. N. Francis, Computational analysis of present-day English, Providence, RI: Brown Univ. Press, 1967, count); above 399/million, the closed class had an almost-flat function of reaction time versus the logarithm of the frequency, while the open class may have had too few members for meaningful assessment. Because reaction time may be a nonlinear function of log frequency, and because there is relatively little overlap between the frequency ranges of the two classes, comparisons of the members of the two classes which might straddle the function's inflection point must be made with extreme caution.     

Reversal operations after brain damage

The ability to perform reversals—that is, the appreciation of the relationship between original and transformed states of knowledge—is critical to human thought processes. In order to assess whether a number of “special-purpose processors” are responsible for reversal operations, depending on the particular context in which the reversal is couched, or whether a single “core processing mechanism” subserves a critical aspect of reversal operations regardless of the specific context, patients with localized brain damage were asked to solve eight reversal problems. Visual and auditory reversals mediated by linguistic and non-linguistic symbol systems were presented. The findings demonstrate that patients with insult to the anterior portion of the right hemisphere encounter more difficulty performing reversals than patients with right posterior insult, Broca's aphasics, and fluent aphasics. This is regardless of the symbol system mediating the reversal, regardless of the modality of presentation, and regardless of the amount of available processing time. Subjects with insult to the posterior region of the left hemisphere or the right hemisphere also exhibit some difficulty solving reversal problems, although their difficulties appear modality specific. These data lend support to the claim that a core processing mechanism may play a critical role in the performance of reversal operations.     

Schema induction and analogical transfer

An analysis of the process of analogical thinking predicts that analogies will be noticed on the basis of semantic retrieval cues and that the induction of a general schema from concrete analogs will facilitate analogical transfer. These predictions were tested in experiments in which subjects first read one or more stories illustrating problems and their solutions and then attempted to solve a disparate but analogous transfer problem. The studies in Part I attempted to foster the abstraction of a problem schema from a single story analog by means of summarization instructions, a verbal statement of the underlying principle, or a diagrammatic representation of it. None of these devices achieved a notable degree of sucess. In contrast, the experiments in Part II demonstrated that if two prior analogs were given, subjects often derived a problem schema as an incidental product of describing the similarities of the analogs. The quality of the induced schema was highly predictive of subsequent transfer performance. Furthermore, the verbal statements and diagrams that had failed to facilitate transfer from one analog proved highly beneficial when paired with two. The function of examples in learning was discussed in light of the present study.     

Training referential communication skills: The limits of success

We explored why an effective speaker-training technique failed to generalize to listener skills by comparing the relative effectiveness of speaker and listener training. Our hypotheses were that: either listening tasks utilize different skills than speaking tasks (thus one should not expect transfer), or the acquisition of listener skills precedes the acquisition of speaker skills (thus the transfer patterns tested in our previous research—speaker to listener—violated the normal developmental sequence), or there is no spontaneous transfer between tasks in different modalities (even though such tasks require the use of some of the same skills). This research utilized a referential communication paradigm. Five-year-olds received either speaker training, listener training, or both speaker and listener training. Children were tested for transfer on speaking and listening task after a 1-week delay. The results suggest that although speaking and listening tasks appear to require, at least in part, certain of the same skills, preschoolers do not exhibit spontaneous intermodality transfer. Theoretical implications for the relationship between speaker and listener skills are discussed.     

Career development of special populations: A framework for research

In view of the recent interest in the career behaviors of diverse groups of individuals, this article presents a model for conducting research on the career development of special populations. Available research paradigms are reviewed in terms of their potential impact on such efforts. An alternative framework, designed to make maximum use of available data sources while minimizing potential theoretical bias, is offered. An illustration of research conducted within the recommended framework is presented in which the impact of a variety of career-related variables on the attitudinal and cognitive aspects of vocational maturity is examined from the perspective of two special population groups, disabled and disadvantaged college students. Drawing upon previous research findings, variables under consideration included level of scholastic achievement and endorsement of rational, intuitive, and dependent decision-making styles. Also included were two population-specific variables related to the characteristics of membership in each of the two special groups. The regression analyses conducted to explore the relationships between vocational maturity and these predictor variables indicate, in general, that variance in the attitudinal and cognitive factors of vocational maturity can be at least partially explained by the variables considered. However, the relative contributions of the predictors and the resulting proportions of variance explained differs according to which population and which criterion factor is under examination. These findings are compared with those emerging from previous research, and implications for future efforts are discussed.     

Surprise but not coherence: Sensitivity to verbal humor in right-hemisphere patients

Verbal humor deficits were investigated in right-hemisphere-damaged patients. It was hypothesized that the appreciation of jokes presupposes two elements: sensitivity to the surprise element entailed in the punch line of a joke and apprehension of the coherence which results when the punch line has been integrated with the body of the joke. The possible dissociation between these elements was tested by asking subjects to select from four alternatives the appropriate ending to a joke. Right-hemisphere patients exhibited a selective attraction to endings which contained an element of surprise but which were not otherwise coherent with the body of the joke. This finding suggests that right-hemisphere patients have difficulty in integrating content across parts of a narrative and confirms the psychological reality of the proposed distinction between the surprise and coherence elements of humor processing.     

Memory in educable mentally retarded adults: Deficit in subject or experimenter?

Educable mentally retarded (EMR) and nonretarded adults free recalled lists of (a) words, (b) minitasks performed by the subjects (SPTs), (c) minitasks performed by the experimenter (EPTs), or (d) task instructions. The EMR subjects were significantly inferior to the nonretarded subjects in the immediate recall of words, EPTs and instructions, but not in the immediate recall of SPTs. This proficiency of the EMR subjects in SPT recall was attributed to the nonstrategic nature of this test. The EMR subjects were, however, inferior to the nonretarded subjects in a final free recall (recall of all lists) of all four types of item.     

The influence of chance and contingency factors on the vocational choice process of nonprofessional workers

The present study investigated the perceived influence of chance and contingency factors on the career choices of nonprofessional workers. The sample was composed of 447 female workers and 470 male workers. As part of a larger study the workers listed the factors that had influenced their choice of their first job, their present job, and their most satisfying job. They were also asked to consider their entire work history and note events, people, or personal inclinations which influenced their vocational decisions. The workers then rated each of 27 chance or contingency factors concerning the extent of influence (great, some, none) on their career choices. The results are examined and discussed relative to the perceived importance of chance and contingency factors on the career choices of nonprofessional workers. The implications of the results for vocational theory and career counseling are considered.