Lateralization of temporal lobe dysfunction and verbal encoding

The contribution of encoding deficits to verbal-learning difficulties known to be associated with temporal lobe dysfunction was investigated. Auditory and visual false-recognition tasks, which assess verbal encoding strategies, were given to patients with left-temporal-lobe (LTL) and right-temporal-lobe (RTL) surgical excisions and to a group of normal controls (NC). On both auditory and visual tasks, LTL patients made significantly more false-recognition errors than the other subjects on related, but not unrelated, words in the test list. The findings indicate that LTL patients are able to initially encode verbal material and that a breakdown in information processing occurs at a later stage. On the auditory tasks, the performance of RTL patients did not differ from that of NC subjects. However, on the visual tasks, RTL patients, as compared to both LTL and NC subjects, made fewer false-recognition errors. The performance of RTL patients, in contrast to LTL patients, could be interpreted as a reduced encoding of the visual attribute of verbal material. Another possible explanation considered was difficulty in familiarity discrimination.     

Mechanisms underlying writing and speech in aphasia

As a parallel to the dual decoding concept for processing of written language we proposed that phonological encoding does not necessarily occur in writing and that the phonemic and graphemic subsystems can be independent on the one-word level. This hypothesis was tested by comparing oral and written performance in a picture-naming task in Broca's and Wernicke's aphasics. In addition, the residual tacit knowledge of the orthographic properties of the names of the pictures was examined with a multiple-choice recognition task. The principal finding is that Broca's aphasics who were better in written than in oral naming showed more graphemically and semantically motivated errors than aphasics who were better in oral than in written naming, the latter producing more phonemically motivated errors. This result supports the dual encoding concept for writing on the singleword level, implying a direct route from the mental lexicon to the graphemic system in parallel with a route mediated by the phonemic system. Multiple-choice recognition was found to be superior to both oral and written performance in both Broca's and Wernicke's aphasics.     

Rate reduction strategies used by normally fluent and stuttering children and adults

Speech rate can be reduced by prolonging the duration of phonetic units, by pausing between words, or through a combination of these approaches. Child and adult normally fluent speakers and stutterers were tested in basal and modified speaking rate conditions. Subjects' utterances in both conditions were converted to spectrographic displays so that measures of phonetic and pause durations could be made. Comparisons of these measures across conditions revealed that all four groups of subjects spontaneously extended pause and phonetic durations, the former more than the latter, when instructed to voluntarily reduce speech rate.     

Speech timing skills of normally fluent and stuttering children and adults

This study was designed to explore the speech timing skills of normally fluent and stuttering children and adults producing two sentences, ten consecutive times at basal and modified speaking rates. Spectrographic displays of subjects' utterances in both conditions were made in order to obtain consonant, vowel, pause, and utterance duration measures. Results showed that (1) the two groups of children produced speech durational values similar to those of the two adult groups and (3) there were no consistent between- and within-group differences in the basal and modified rate conditions. Findings are discussed in terms of methodological and sampling differences that exist between the present study and past research on stutterers' speech production abilities.     

The effect of a commercial game on children's block design scores on the WISC-R IQ test

Two experiments investigated the extent to which 10-year old children's scores on the WISC-R Block Design subtest were affected by prior experience with a specific commercial game that involved blocks and matching patterns. Experiment 1 found that 12 10-year old children who happened to have experience with the particular commercial game scored approximately three scaled score points higher on the WISC-R Block Design subtest than 24 matched children without game experience. In Experiment 2, 24 children who did not have prior experience with this particular commercial game were randomly assigned either to a Game condition (involving two 15-minute sessions with the game) or to a No-Game condition (which involved no further game experience). Children in the Game condition subsequently increased their WISC-R Block Design scores more than children in the No-Game condition. Taken together, the experiments indicate that relatively brief interactions with a commercial game can cause a significant improvement in children's performance on an IQ subtest.     

Children's understanding of food and its functions: A preliminary study of the development of concepts of nutrition

Children's developing conceptions of how the body functions nutritionally were examined. Two different tasks provided converging findings. One task asked children to judge the causes of certain end states (e.g., why X is fat). The second task asked children to judge the result of certain contrasting diets (e.g., twin-1 eats twice as much candy as twin-2). The results evidenced; (a) systematic misconceptions on the part of kindergarteners that were overcome by sixth grade; and (b) other fairly sophisticated conceptions present even at the youngest ages tested. The research provides a needed first step toward describing the naive theories of nutrition possessed by children at different ages. Knowledge of childrens' theories of nutrition are essential for optimal planning of curricula and methods in nutrition education.     

Speech prosody in Broca's aphasia

Because speech prosody is thought to be impaired in Broca's aphasia, we conducted three experiments using Broca's aphasics and nonneurological control subjects in order to determine to what extent this statement is accurate. Using three acoustic measures of speech prosody—sentence-final fundamental frequency (F₀) fall, F₀ declination, and sentence-final lengthening—we found that some aspects of prosody were spared while others were abnormal. All Broca's aphasics, regardless of degree of impairment, exhibited sentence-final F₀ fall. F₀ declination was present in simple sentences but was absent over longer domains; moreover, the amount of declination was correlated with the degree of linguistic impairment. Sentence-final lengthening was clearly absent in Broca's aphasia; in fact, sentence-terminal words were actually shorter than their sentence-initial and medial counterparts.     

Cerebral lateralization, preferred cognitive mode, and reading ability in normal children

In a sample of 105 children (aged 6 to 12), a stylistic preference for a verbal approach to problem-solving correlated positively with reading ability (independently of age) and degree of right-ear advantage in the report of dichotic stop consonant-vowel syllables (but not with verbal intelligence or hand preference). Verbal strategic preference may: (1) foster the acquisition of reading skill, and (2) bias attention toward input from the right by generating differential left-hemisphere activation.     

Limb apraxia and motor performance

This study was desinged to determine if motor deficits in limb apraxia are task specific. Non-brain-damaged patients and apraxic and nonapraxic patients with left hemisphere damage performed language and limb apraxia tests and six motor tasks with the left hand. Contrary to previous data, no significant group differences occurred on a finger tapping task. Although task complexity or sequencing requirements affected group differences, greatest apraxic impairment was noted on a task of precise steadiness, but only when its response inhibition requirements were increased. This pattern of deficits appears to be associated with greater involvement of the premotor area in the apraxic group.