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Biomedical subjects

L L Morton

Publications and source records attributed to L L Morton.

17 recordsLinked to original sources
PubMed1997

Student teacher anxieties related to class management, pedagogy, evaluation, and staff relations.

BACKGROUND: Anxiety is an important consideration in teaching, with implications for classroom success. AIMS: We investigated the nature of anxiety in student teachers. SAMPLES: Approximately 1000 student teachers in Canada were involved in four studies to explore education-related anxieties. METHODS: Incorporating a cross-cultural focus, student teachers were tested on an anxiety measure designed for British student teachers, then examined for (1) the impact of practice teaching, (2) the value of instructional preparation, (3) demographic variables, and (4) models that predict anxiety. RESULTS: Anxiety factors (i.e., evaluation, pedagogical, class management, and staff relations), similar to those for British participants, emerged with evaluation anxiety being highest. A practice teaching experience generated reduced anxiety for both sexes, but more so for females, with the greatest reductions for evaluation and pedagogical anxiety. In one study, participants reported anxieties prior to instruction (PRETEST), following instruction (POST-INSTR) and following practice teaching (POST-TEACH). Females showed higher anxiety ratings than males (PRETEST and POST-INSTR) but were comparable to males after practice teaching. Females in the lower grades division showed higher anxiety scores. Anxiety decreased between PRE-TEST and POST-INSTR for all four scales, and between POST-INSTR and POST-TEACH for evaluation, pedagogy and staff relations; however, class management anxiety did not decrease after practice teaching. Also, anxiety increased as placement grade level decreased. All models (demographic, experiential, and dispositional) were predictive but the best predictor was the psychological disposition to feel overwhelmed. CONCLUSIONS: Student-teacher anxieties are related to demographic variables, experiential variables, and dispositional variables.

Adult↗
PubMed1995

Circadian differences in hemisphere-linked spelling proficiencies.

Male and female adolescents (N = 113) were assigned randomly to spelling instruction in either morning or afternoon groups for a school year. A spelling list (100 words) was administered at the beginning of the school year to obtain a sample of error responses and estimate proficiency. Although equally proficient, subjects tested in the afternoon showed more phonetically inappropriate errors, while those tested in the morning showed more phonetically appropriate errors. This error pattern is viewed as support for a more engaged left hemisphere in the morning. There were no differences on two types of visual errors. Subjects then received instruction in spelling for nine months in either morning or afternoon settings. Time-of-day effects were not evident on the word list and there were too few errors to conduct a posttest error analysis. However, standardized test results for a subgroup revealed that subjects receiving morning instruction made greater gains on phonetically regular words compared to phonetically irregular words--an effect consistent with a circadian-linked higher level of left hemisphere engagement early in the day. The findings are of a pilot nature, but implications for education and further research are discussed.

Achievement↗
PubMed1994

Interhemispheric balance patterns detected by selective phonemic dichotic laterality measures in four clinical subtypes of reading-disabled children.

Identifying disabilities in word-attack, word-recognition, or reading comprehension, allowed for four categories of reading disability: (1) reading comprehension only (RC), (2) word-attack plus comprehension (WA+RC), (3) word-attack, word-recognition, and comprehension (WA+WR+RC), and (4) word-attack but not comprehension (WA-RC). Along with age-matched controls (AMC) and developmental-delay controls (DDC), the disabled were tested on a directed-attention dichotic task using consonant-vowel combinations. Laterality results for each place of articulation (i.e., bilabial, alveolar, and velar) selectively attested to greater left hemisphere involvement or engagement for the RC group and greater right hemisphere involvement or engagement for the WA+RC group. Performance of the other two disabled groups was consistent with less efficient right hemisphere involvement or callosal transfer. Implications for theory, research, and remediation are discussed.

Attention↗
PubMed1994

Hemisphericity and information processing in North American Native (Ojibwa) and non-native adolescents.

Thirty-two male and female adolescents of native ancestry (Ojibwa) and 32 controls were tested using (1) four WISC-R subtests and (2) two dichotic listening tasks which employed a focused-attention paradigm for processing consonant-vowel combinations (CVs) and musical melodies. On the WISC-R, natives scored higher than controls on Block Design and Picture Completion subtests but lower on Vocabulary and Similarities subtests. On laterality measures more native males showed a left ear advantage on the CV task and the melody task. For CVs the left ear advantage was due to native males' lower right ear (i.e., left hemisphere) involvement. For melodies, the laterality index pointed to less left hemisphere involvement for native males, however, the raw scores showed that natives were performing lower overall. The findings are consistent with culturally-based strategy differences, possibly linked to "hemisphericity," but additional clarifying research regarding the cause and extent of such differences is warranted. Thus, implications for education are premature but a focus on teaching "left hemisphere type" strategies to all individuals not utilizing such skills, including many native males, may prove beneficial.

Adolescent↗
PubMed1993

Cognitive and neuropsychological response asymmetries for adults on the left-right seating axis.

Six studies of the relationship between classroom seating and information processing were conducted with adult subjects. Findings converged to support a hemisphericity-based explanation of effects with right-side-sitters more inclined to a response style associated with the right hemisphere--perhaps, less analytical or less cautious in responding (Experiments 1-4), more "artistic" (Experiment 5), and less lateralized (Experiment 6), and vice versa for left side sitters. First, using incidental memory tasks, subjects (N = 164) with a right side seating preference (i.e., to the speaker's left side) were found, in their test-taking behavior, to respond more positively to inaccurate distractor words (Experiments 1 and 2), particularly those with an ambiguous semantic reference (Experiment 3). For different levels of processing, seating location did not influence auditory memory (Experiments 1 and 2) but right side sitters showed enhanced visual memory for accurate words (Experiment 3). In a sample of 366 subjects, males selecting right side seating were less successful on multiple-choice test performance (Experiment 4), but there were no Side differences in test taking speed or review time. In a sample of 286 subjects (Experiment 5), personality measures on the Vocational Preference Inventory revealed right sitters scored higher on the "Artistic" scale and on femininity on the Masculine-Feminine scale. The final study (N = 90) revealed reduced dichotic processing on verbal tasks (digits and voiced CVs) for right side sitters. Implications are discussed.

Adult↗
PubMed1993

Circadian differences in the dichotic processing of voicing.

Male and female adult subjects (N = 112) were tested at two times (morning and afternoon) for time-of-day related shifts in linguistic processing on dichotic listening tasks using (1) a divided-attention paradigm for processing digits (0-9) and (2) a focused-attention paradigm for processing consonant-vowel (CV) combinations which were grouped according to the voiced and unvoiced stop consonants. Time-of-day effects were not evident on digits using the divided-attention paradigm. However, on CVs a predicted two-way interaction for Time-of-Day Voicing-due to superior detection of voiced stimuli in the afternoon-was evident. This effect is consistent with a circadian-linked increase in right hemisphere involvement later in the day. Implications for theory, research and educational applications are discussed.

Adult↗
PubMed1991

Left ear dichotic listening performance on consonant-vowel combinations and digits in subtypes of reading-disabled children.

Twenty reading comprehension-disabled (CD) and 20 reading comprehension and word recognition-disabled (CWRD), right-handed male children were matched with 20 normal-achieving age-matched controls and 20 normal-achieving reading level-matched controls and tested for left ear report on dichotic listening tasks using digits and consonant-vowel combinations (CVs). Left ear report for CVs and digits did not correlate for any of the groups. Both reading-disabled groups showed lower left ear report on digits. On CVs the CD group showed a high left ear report but only when there were no priming precursors, such as directions to attend right first and to process digits first. Priming effects interfered with the processing of both digits and CVs. Theoretically, the CWRD group seems to be characterized by a depressed right hemisphere, whereas the CD group may have a more labile right hemisphere, perhaps tending to overengagement for CV tasks but vulnerable to situational precursors in the form of priming effects. Implications extend to (1) subtyping practices in research with the learning-disabled, (2) inferences drawn from studies using different dichotic stimuli, and (3) the neuropsychology of reading disorders.

Attention↗
PubMed1991

Effects of time-of-day on neuropsychological testing as measured by dichotic listening.

In a study of 30 reading-disabled and 30 normal-achieving children tested on a dichotic listening task using digits in either morning or afternoon settings neither laterality nor capacity differences were evident between groups in the afternoon. In the morning, the normal-achieving children compared to the disabled readers were more strongly lateralized when attending selectively to the right channel and less lateralized when attending to the left channel, suggesting disabled readers do not respond normally to circadian influences and may suffer from a time-locked dysfunction which reduces their control over attentional resources in the morning. To examine the normal circadian effect further a second study (using 40 normal-achieving, right-handed male children) was conducted using the same dichotic listening stimuli with an order variable included. The increased report in the morning was seen to be linked to a right ear (left hemisphere) priming effect which served to increase the overall report. The effect was evident only for subjects directed to report the right ear first. The results are consistent with a prepotent left hemisphere in the morning which appears to facilitate attending in the morning for subjects directed to attend to their right ear (left hemisphere) first. Potential research and educational implications are discussed.

Arousal↗
PubMed1990

Differential negative air ion effects on learning disabled and normal-achieving children.

Forty normal-achieving and 33 learning disabled (LD) children were assigned randomly to either a negative ion or placebo test condition. On a dichotic listening task using consonant-vowel (CV) combinations, both groups showed an ion-induced increase in the normal right ear advantage (REA). However, the mechanisms for this effect were different for each group. The LDs showed the effect at the right ear/left hemisphere (enhancement). The normal achievers showed the effect at the left ear/right hemisphere (inhibition). The results are consistent with an activation-inhibition model of cerebral function and suggest a functional relationship between arousal, interhemispheric activation-inhibition, and learning disabilities. The LDs may have an interhemispheric dysfunction. Both groups showed superior right ear report and the normal achievers showed overall superiority. Normal achievers showed higher consonant intrusion scores, probably due to a greater cognitive capacity. Age was a significant covariate reflecting developmental capacity changes. Negative air ions are seen to be a tool with potential theoretical and remedial applications.

Air Ionization↗
PubMed1990

Directed attention dichotic listening in reading disabled children: a test of four models of maladaptive lateralization.

In two experiments, critical a priori tests compared four competing LD theories of maladaptive language lateralization (Poor Structural Lateralization; Excessive RH Activation; Excessive LH Activation; Excessive LH or RH Activation). In Experiment 1, 32 auditory-linguistic LD children from public schools were compared to 32 high-achieving, age-matched controls. Experiment 2 replicated the main findings of Experiment 1 by comparing 14 LD children to 14 controls attending a private school. The effect of priming or ear order was analyzed in a directed attention, dichotic paradigm with strings of quadruple digit names as stimuli. The order in which the ears were monitored (LE first or RE first) determined (1) in both experiments whether the LD children compared to controls were more weakly or strongly lateralized and (2) in Experiment 2 whether the REA correlated negatively of positively with reading and spelling achievement. The results indicate that the hemispheric processes involved in disengaging and shifting response strategies between dichotic channels may share common neuronal mechanisms with cognitive processes that are important to school achievement. Rather than LD children suffering from a fixed laterality deficit, the results are consistent with the view that a task-dependent attentional dysfunction may interfere with left hemisphere language processes by overengaging either hemisphere. However, pronounced asymmetry in the relative magnitude of the effects at each channel also suggests greater interference in LD children between the systems controlling auditory-linguistic attention and lateral orienting.

Achievement↗
PubMed1987

Hemisphere asymmetries, spelling ability, and classroom seating in fourth graders.

Fourth grade children (N = 159) from eight classes who were free to select their seating location in the classroom were tested for spelling ability. On 100 word spelling lists, the children (males and females) seated on the right side of the classroom (facing the teacher) were superior to children on the left. Analysis of spelling errors for reliance on phonological processing in a subsample (N = 28) revealed that right sitters made more phonetically inaccurate misspellings, whereas, on the left, females, but not males, committed more phonetically accurate misspellings. The results support the view that hemispheric information processing is correlated with classroom seating location or preference, but casual inferences regarding the neuropsychological mechanisms underlying these findings are unwarranted pending clarification of several major theoretical issues.

Child↗
PubMed1987

Negative ion effects on hemispheric processing and selective attention in the mentally retarded.

The effect of high concentrations of negative air ions on a dichotic digits task was investigated in 19 mentally retarded individuals. Subjects were assigned randomly to an ion or to an unmodified-air placebo condition under double-blind testing. Left and right ears were precued for report order and this order was reversed for the second set of trials. Negative ions promoted greater left hemisphere lateralization on the first set of trials, and enhanced recall when switching to the opposite channels, in the second set of trials. However, the ion-induced REA occurred at the expense of selective attention to the left channel and superior left ear recall after the right ear first condition is an anomalous dichotic listening pattern. Such paradoxical results suggest that negative ions are not necessarily beneficial or detrimental to processing. Negative ions may increase arousal, in this case amplifying a time-phased, information processing disorder in the retarded characterized by excessive right hemisphere inhibition during early processing of receptive speech and diffuse interhemispheric excitatory activation during later processing.

Air Ionization↗
PubMed1987

A sensitive period for the neural induction of taste buds.

Taste buds mature postnatally in the vallate papilla of the rat and reach a mean number of 610 by day 90. Although taste buds are neurotrophically dependent, the presence of widespread bilateral innervation permits more than 80% of the 610 vallate taste buds to survive after one IXth nerve is removed in adults. However, after a IXth nerve is removed at 0-3 d postpartum, about two-thirds of the vallate taste buds fail to develop. In the present investigation, the timing of the neural induction of taste buds was examined by unilaterally removing the IXth nerve at 12 different postnatal ages, from 0 to 75 d. Unilateral denervation revealed the existence of a sensitive period that is maximal from 0 to 10 d, when unilateral or bilateral interruption of the IXth nerve profoundly impairs the formation of taste buds. The number of taste buds that form is nonlinearly dependent upon the number of axons; at low levels of innervation, a doubling of the number of myelinated axons quintuples the number of taste buds. Thus, taste axons interact synergistically. In studying regeneration, we found that axons of both neonatal and adult IXth nerves elongate approximately 1.8 mm/d. Taste buds were re-formed more rapidly and a higher proportion were bilaterally innervated when regenerating axons and the sites of former taste buds were numerous. The proportion of bilaterally innervated taste buds could be approximated from the likelihood of random overlap of axons from the right and left IXth nerves. The greater ease with which taste buds are re-formed than developed suggests that taste bud regeneration does not recapitulate taste bud development.

Animals↗
PubMed1984

Negative air ionization improves memory and attention in learning-disabled and mentally retarded children.

The effect of increased concentrations of ambient negative air ions on incidental visual memory for words and purposive auditory memory for dichotic digits was investigated in 20 normal grade 4 children, 8 learning-disabled children, and 8 mildly mentally retarded children. Half in each group were assigned randomly to an unmodified air-placebo condition under double-blind testing procedures. All of the children breathing negatively ionized air were superior in incidental memory. In dichotic listening, the negative ions produced a counter-priming effect in the two learning-impaired groups, offsetting the difficulties that they showed under placebo in switching attention selectively from one ear to the other. The action of negative ions on the neurotransmitter, serotonin, may be the mechanism by which negative ions produce such behavioral effects. In view of the important environmental and remedial implications of these novel findings, interpretations should be made cautiously pending larger-scale replications.

Air Ionization↗
PubMedDate not supplied

Time-of-day-induced priming effects on verbal and nonverbal dichotic tasks in male and female adult subjects.

Normal adults (32 males and 32 females) were tested for time-of-day related shifts in laterality and priming on two dichotic listening tasks using consonant-vowel combinations (CVs) and musical melodies. The predicted time-of-day effect on melodies was due to males showing low report in the morning, but not the afternoon, suggesting increased right hemisphere involvement in the afternoon. A time-of-day-induced priming effect on the laterality index for CVs differentiated males and females. Males tested morning-first were more lateralized than females, who in turn were more lateralized when tested afternoon-first. A time-of-day-induced priming effect on the laterality index for music indicated those tested afternoon-first showed an overall left ear advantage (LEA), whereas those tested morning-first showed an overall right ear advantage (REA). On raw music scores a sex-linked, time-of-day-induced priming effect was due to the prior presentation of CVs--that is, cognitive priming. Other priming effects on music were evident for order of stimulus presentation and order of ear attended. Implications for theory, research and pedagogy are discussed.

Adult↗
PubMedDate not supplied

Time-of-day and attentional-order influences on dichotic processing of digits in learning disabled and normal achieving children.

A heterogeneous group of 26 learning disabled (LD) and 30 normal achieving (NA) children, responded to a dichotic listening task using digits in morning and afternoon settings. Attentional order (i.e., right ear first versus left ear first) interacted with (1) Time-of-Day and (2) Group and Ear Attended. The first interaction revealed, as predicted, higher morning performance for subjects directed to attend right first. Subjects directed left first showed higher afternoon performance. These results are consistent with enhanced left hemisphere involvement after left hemisphere priming in the morning, and after right hemisphere priming in the afternoon. The second interaction indicated the LD had more difficulty than controls switching attention to the right ear when instructed to attend left first. The LD may activate the right hemisphere (via left hemispace attending) and have difficulty with subsequent right hemisphere inhibition, or left hemisphere activation, when shifting to right ear attending. Nonparametric tests revealed a greater incidence of lateralized responders in the morning for normal achievers attending left first. Findings are seen to augment previous research.

Activity Cycles↗