Delayed alternation in the rat: Effect of contextual stimuli on proactive interference

The effect of contextual stimuli on proactive interference in the rat was investigated in three experiments. The task was a modified delayed alternation procedure in which the rat was initially forced to one side of a T maze (the interfering forcing) followed by a forcing to the opposite side (the target forcing). A free choice run followed the target forcing in which a turn in either direction could be made. In order to obtain reinforcement on the free choice run, the rat was required to turn in the direction opposite that of the target forcing (i.e., in the same direction as the interfering forcing). Manipulation of the context prevailing during the interfering forcing, target forcing, and free choice runs revealed that free choice accuracy was (a) greater when the interfering and target forcings were conducted in different contexts than when they were conducted in the same context and (b) influenced only slightly, if at all, by whether the free choice context coincided with that prevailing during the interfering forcing or with that prevailing during the target forcing.     

Teacher reactions to school-based consultation services: A multivariate analysis

The impact of consultation services on teachers' preferences for consultation versus referral approaches and upon teachers' perceptions of severity for common acting out, withdrawal, and academic types of student problems were investigated. The subjects were 96 teachers whose public and parochial schools were matched and randomly assigned to treatment and control groups. Following a 14-week period during which advanced school psychology graduate students served as consultants in the treatment schools, the Pupil Problem Behavior Inventory (PPBI) was administered to all teachers. The results of a repeated measures MANOVA analysis indicated that the teachers in the treatment group rated the acting out and academic problems on the PPBI as significantly less severe than did teachers in the control group. The subjects in both the treatment and control groups indicated a significant preference for consultation rather than referral services for all types of student problems presented in the PPBI. There was a moderate, positive correlation between perceived problem severity and teacher preference for referral rather than consultation services. The study's results were interpreted as supportive of the consultation model.     

Right hemisphere comprehension of verbs in patients with complete forebrain commissurotomy: Use of the dichotic method and manual performance

The paradigm of dichotic listening was used to investigate verbal comprehension in the right, so-called “nonverbal,” hemisphere. Verbal commands were presented to the right and left ears in the simultaneous (dichotic) paradigm. There were striking instances, especially when the left hemisphere was occupied with some extraneous task, in which the right hemisphere understood the verbal command and executed the appropriate motor responses. In those instances the left hemisphere gave no overt response. Although the left hemisphere was usually dominant, it can be nevertheless concluded that not only can the right hemisphere understand verbal commands but can also express itself manually by executing actions more complex than object retrieval or pointing. As has been known for some time, the blockage of the ipsilateral pathway seems so complete during dichotic listening in the commissurotomy patient that there is no report of the words in the left ear—only of those presented to the right. At the same time there is normal report when words are presented to the left ear alone. It was found in the present study, however, that this model is too simple and only applies to the verbal response paradigm of dichotic listening. Under circumstances of dichotic presentation where the stimulus in the left ear (ipsilateral pathway) is necessary or important to the left hemisphere for completing a task, words from both pathways are reported. One may conclude that there exists a gating mechanism in each hemisphere that controls the monitoring of each auditory pathway and the degree of ipsilateral suppression.     

A twin study of personality and temperament during middle childhood

In a study of 105 same-sex twin pairs, ages 7 to 10 years, maternal ratings on 23 bipolar scales yielded six factors designated as compliant morality, applied cognitive, sociability, emotionality, tough-mindedness, and activity-distractibility. Analyses by twin pairs (68 identical, 37 fraternal) indicated that correlations for identical pairs were significantly higher than fraternal pairs on all but one factor: tough-mindedness. Profile analyses for the six factors indicated that the profiles of scores across the factors were more concordant for the identical twin pairs. Correlations obtained from the individual scales produced differences between the identical and fraternal twin pairs as well. Overall, the data suggested that several components and the total organization of those components of personality and temperament are genetically influenced.     

Cognitive task effects on hemispheric blood flow in humans: Evidence for individual differences in hemispheric activation

Evidence from two indirect measures of hemispheric activity, EEG α and conjugate lateral eye movements, has pointed to the existence of individual differences in hemispheric activation. Results from a more direct indicator of hemispheric activity, regional cerebral blood flow as measured by the ¹³³Xe inhalation method, show that such individual differences can be detected in the distribution of blood in the two hemispheres and that the amount of increase in blood flow in the right relative to the left hemisphere is correlated with performance on a spatial task. These results corroborate and extend the findings from the EEG and eye movement studies and suggest that the dimension of individual differences in hemispheric activation may exert significant influence on cognitive performance and on problem-solving strategies.     

Unilateral agraphia after section of the posterior half of the truncus of the corpus callosum

Children ranging in age from 3 to 12 tapped on a morse key with their index finger as fast as possible. After a control test, they concurrently tapped and recited a nursery rhyme, recited animal names, and memorized shapes. Previous results suggested that more interference in a motor task results from attempting at the same time to perform another task controlled by the same, than by a different, hemisphere. Right-handed tapping and talking both used left hemisphere space; left-handed tapping and talking were controlled by different hemispheres. Relative to silent tapping concurrent talking caused a greater drop in right-hand tapping rate than in left-hand tapping rate in both the rhyme and animal conditions. Interference by shape memorizing was equal across hands. The differential effect of speaking on right-hand preference indicates the left lateralization of speech output control. The size of this effect did not vary with increasing grade level. The findings support the view that speech output control is fully lateralized at least by age 3 years.     

Verbal and nonverbal recognition memory in aphasic and nonaphasic stroke patients

The ability to retain lists of verbal and nonverbalizable items across recurrent recognition tasks was tested in three groups: (1) stroke patients with a left-brain lesion and aphasia, (2) stroke patients with a right-brain lesion and left hemiplegia, and (3) nonneurologically impaired outpatients. As determined with signal detection measures, aphasics were deficient in discriminating words that were to be remembered from those that were not; their recognition of nonverbal visual (geometric art) or auditory (bird calls) patterns, however, was unimpaired. Left hemiplegics showed the opposite pattern. After a long-term interval (<10 min), correct recognition of words was diminished in all groups whereas recognition of visual patterns increased. Both groups of stroke patients adopted material-specific decision criteria which in part accounted for the dissociation of verbal and nonverbal recognition memory by laterality of lesion. Item analysis indicated that aphasics' verbal memory difficulties were affected by acoustic-semantic confusion of list words.     

Right-hemisphere speech representation and comprehension of syntax after left cerebral injury

Comprehension of language and visuo-spatial abilities were studied in 12 surgical patients with left cerebral lesions and right-hemisphere speech representation verified by sodium amobarbital tests. When left-hemisphere symptoms preceded the acquisition of speech, impaired understanding of syntactically complex sentences was associated with an early, but not late, onset of convulsive seizures. Other behavioral measures did not show a similar effect of age at seizure onset. Sparing or loss of comprehension could not be related to any aspects of the neurological histories in cases with right-hemisphere speech acquired before the onset of left-hemisphere symptoms. Factors which may have influenced the development of right-hemisphere language comprehension are discussed.     

Eye movements and performance during bilateral tracing tasks

To examine the role of current visual monitoring in the between-hand differences in skilled movements, eye movements and errors during bilateral tracing tasks were analyzed in 10 subjects. When subjects traced a horizontal course abductively with both hands, the subject's gaze followed the movement of the right hand, and more errors were observed on the left hand. When subjects traced a vertical course, where fine motor control for alteration of movement direction was necessary, more errors were shown on the left hand despite the alternate visual scan of the two hands. The results were interpreted as showing that the between-hand differences in skilled movements are primarily due to the left hand's poor ability in motor output, and that the differential efficiency in the use of visual monitoring becomes an important factor in the between-hand differences when symmetrical movements of both hands with a low degree of difficulty are required.