Producing Ethnographies: Workplace Ethnographies in History

Data on a large set of workplace ethnographies published from 1940 to 2002, compiled by Randy Hodson, are analyzed to show the trends over time in the production of such ethnographic work, its shifting disciplinary base, the relevance of the personal backgrounds of its authors, the contributions made by academic amateurs, the changing roles of gender and political stances, and the nature of different routes to publication. The definition of what counts as an ethnography is important to the character of the set available and has implications for its potential uses in secondary analysis. It is found that both personal and disciplinary identities and wider social factors have played roles in the production of ethnographic work that need to be understood to account for its history, though it is to be expected that the forms these take will differ for work in different subfields.     

Construct Validity of Raven's Advanced Progressive Matrices for African and Non‐African Engineering Students in South Africa

We test the hypothesis that the Raven's Advanced Progressive Matrices has the same construct validity in African university students as it does in non‐African students by examining data from 306 highly select 17‐ to 23‐year olds in the Faculties of Engineering and the Built Environment at the University of the Witwatersrand (177 Africans, 57 East Indians, 72 Whites; 54 women, 252 men). Analyses were made of the Matrices scores, an English Comprehension test, the Similarities subscale from the South African Wechsler Adult Intelligence Scale, end‐of‐year university grades, and high‐school grade point average. Out of the 36 Matrices problems, the African students solved an average of 23; East Indian students, 26; and White students, 29 (p<.001), placing them at the 60th, 71st, and 86th percentiles, respectively, and yielding IQ equivalents of 103, 108, and 118 on the 1993 US norms. The same pattern of group differences was found on the Comprehension Test, the Similarities subscale, university course grades, and high‐school grade‐point average. The items on the Matrices ‘behaved’ in the same way for the African students as they did for the non‐African students, thereby indicating the test's internal validity. Item analyses, including a confirmatory factor analysis, showed that the African/non‐African difference was most pronounced on the general factor of intelligence. Concurrent validity was demonstrated by correlating the Matrices with the other measures, both individually and in composite. For the African group, the mean r=.28, p<.05, and for the non‐African group, the mean r=.27, p<.05. Although the intercepts of the regression lines for the two groups were significantly different, their slopes were not. The results imply that scores on the Raven's Matrices are as valid for Africans as they are for non‐Africans.     

Children with Specific Language Impairment are not impaired in the acquisition and retention of Pavlovian delay and trace conditioning of the eyeblink response

Three converging lines of evidence have suggested that cerebellar abnormality is implicated in developmental language and literacy problems. First, some brain imaging studies have linked abnormalities in cerebellar grey matter to dyslexia and specific language impairment (SLI). Second, theoretical accounts of both dyslexia and SLI have postulated impairments of procedural learning and automatisation of skills, functions that are known to be mediated by the cerebellum. Third, motor learning has been shown to be abnormal in some studies of both disorders. We assessed the integrity of face related regions of the cerebellum using Pavlovian eyeblink conditioning in 7–11 year-old children with SLI. We found no relationship between oral language skills or literacy skills with either delay or trace conditioning in the children. We conclude that this elementary form of associative learning is intact in children with impaired language or literacy development.     

Is auditory discrimination mature by middle childhood? A study using time‐frequency analysis of mismatch responses from 7 years to adulthood

Behavioural and electrophysiological studies give differing impressions of when auditory discrimination is mature. Ability to discriminate frequency and speech contrasts reaches adult levels only around 12 years of age, yet an electrophysiological index of auditory discrimination, the mismatch negativity (MMN), is reported to be as large in children as in adults. Auditory ERPs were measured in 30 children (7 to 12 years), 23 teenagers (13 to 16 years) and 32 adults (35 to 56 years) in an oddball paradigm with tone or syllable stimuli. For each stimulus type, a standard stimulus (1000 Hz tone or syllable [ba]) occurred on 70% of trials, and one of two deviants (1030 or 1200 Hz tone, or syllables [da] or [bi]) equiprobably on the remaining trials. For the traditional MMN interval of 100–250 ms post-onset, size of mismatch responses increased with age, whereas the opposite trend was seen for an interval from 300 to 550 ms post-onset, corresponding to the late discriminative negativity (LDN). Time-frequency analysis of single trials revealed that the MMN resulted from phase-synchronization of oscillations in the theta (4–7 Hz) range, with greater synchronization in adults than children. Furthermore, the amount of synchronization was significantly correlated with frequency discrimination threshold. These results show that neurophysiological processes underlying auditory discrimination continue to develop through childhood and adolescence. Previous reports of adult-like MMN amplitudes in children may be artefactual results of using peak measurements when comparing groups that differ in variance.     

Models for choice-reaction time

In the two-choice situation, the Wald sequential probability ratio decision procedure is applied to relate the mean and variance of the decision times, for each alternative separately, to the error rates and the ratio of the frequencies of presentation of the alternatives. For situations involving more than two choices, a fixed sample decision procedure (selection of the alternative with highest likelihood) is examined, and the relation is found between the decision time (or size of sample), the error rate, and the number of alternatives.     

Suitability of published neuropsychological test norms for urban African secondary school students in South Africa

Variations in neuropsychological test performance as a function of ethnic/cultural group membership, socioeconomic and educational status are widely documented. In South Africa, issues of cultural difference, sociopolitical disadvantage, cognitive and educational limitations, are of particular relevance. Accordingly, this study investigated the performance on a neuropsychological test battery of urban African high school students. A group of 100 Soweto students in Grades 8–12, and a second group of 152 sixth grade Soweto students aged 13–15 years, scored significantly lower on most of the measures than their American counterparts, as reflected in published norms. Results also demonstrated a significant difference in test performance as a function of educational grade. The findings confirmed the need for using norms and approaches which are appropriate to a given population when interpreting and addressing neuropsychological test performance.