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Biomedical subjects

R Ashton

Publications and source records attributed to R Ashton.

At least 37 records · Page 2Linked to original sources
PubMed1994

Function and the patient with chronic low back pain.

OBJECTIVE: To undertake a comparative examination of the reliability and validity of two frequently used self-report measures of functional disability, the Pain Disability Index (PDI) and the Oswestry Low Back Pain Disability Questionnaire (OLBPDQ). DESIGN: A descriptive ex-post facto design was used in the study. SETTING: Pain clinics and neurosurgical units at three metropolitan hospitals. SUBJECTS: One hundred patients with chronic low back pain of noncancer origin were administered the two questionnaires as part of a larger questionnaire battery. RESULTS: Acceptable internal consistency values of 0.76 for the PDI and 0.71 for the OLBPDQ were obtained. A correlation of r = 0.63 was found between the PDI and the OLBPDQ, supporting the concurrent validity of the two scales. Both the scales were found to be correlated to the Beck Depression Inventory scores (PDI, r = 0.42; OLBPDQ, r = 0.39), with higher disability associated with greater depression. Only the total PDI score was found to be sensitive to functional status differences within the patient sample. CONCLUSIONS: These findings support other recent work in favor of the PDI. The PDI had a slightly higher internal consistency and was more sensitive than the OLBPDQ.

Adult↗
PubMed1992

Language lateralization in bilinguals: more not less is needed: a reply to Paradis (1990).

Paradis (1990) took an extremely pessimistic view of research to date looking at the lateralization of cerebral function in bilingual subjects. We, however, argue that some of his conclusions are, in fact, incorrect, while others speak more to the youth of the field. The problems in the latter body of work are now acknowledged and are being overcome. That the shortcomings are recognized seems to be more a case for satisfaction than of despair.

Brain Diseases↗
PubMed1992

Characteristics of the frequent nightmare sufferer.

Previous research has found that persons who experience frequent nightmares score highly on scales that measure psychotic symptomatology. Neurotic symptoms have also been implicated as correlates of nightmare frequency. In this study, 30 adult lifelong nightmare sufferers were compared with 30 control subjects, matched for age, sex, and socioeconomic status. Subjects were asked to record all dreams for 1 month and to complete the Minnesota Multiphasic Personality Inventory (MMPI) and the Eysenck Personality Questionnaire (EPQ). Nightmare subjects scored significantly higher on the EPQ Neuroticism scale and on 8 MMPI clinical scales than did the control group. These scales also best discriminated between the groups in a direct discriminant analysis. The results are interpreted as a reflection of global maladjustment rather than of specific psychotic symptomatology.

Adolescent↗
PubMed1992

The apparent shape of afterimages in the Ames room.

When observers project afterimages of circular patterns onto a surface slanting away from them the images are reported as being oval in shape. In this paper it is reported that this does not occur when similar afterimages are projected onto the slanting rear wall of an Ames room. Instead of appearing as ovals, the afterimages remain circular. It appears as though the actually-slanted rear wall of the room not only looks as if it is normal to the line of vision, but also that it functions as if it was in such an orientation as far as a projection surface for afterimages is concerned. While these results are consistent with Emmert's law and with traditional accounts of shape and size constancy, they raise once again the age-old issue of whether the 'image on the retina' constitutes an object of perception that can be described in terms of its shape or size.

Adult↗
PubMed1991

A simple dual-task study of laterality, sex-differences and handedness.

Nine-hundred and eighty-one right-handed and 55 left-handed subjects were required to tap with a pen for 10 secs between targets 6 cm apart whilst either saying nothing, reciting a tongue-twister or saying la-la. The numbers of dots produced in 10 secs in each condition were analysed. The right-handed group demonstrated the usually found degradation in their right-hand performance whilst reciting the meaningful words, but showed a lesser effect when saying la-la. Their left-handed performance was essentially unaffected. Absolutely no evidence for the presence of a sex difference in lateralization of language was found. The much smaller sample of left-handed subjects presented a complex picture of no significant effects, whether they were the sole left-handers in their family, or had other left-handed close relations.

Adolescent↗
PubMed1991

Pain intensity measurement in chronic low back pain.

This study investigated the psychometric properties of eight pain intensity measures used with chronic low back pain patients. All measures were similar in terms of scale distribution and rates of incorrect responses, with all scales apart from the Pain Rating Index significantly correlated. Principal axis factoring of data from 92 patients indicated the presence of one general factor on which all pain intensity measures except the Pain Rating Index loaded. The 101-point Numeric Rating Scale and the Box Scale had the strongest relationship, with loadings of 0.90. The Numeric Rating Scale and the Box Scale appear to be the scales of choice for the measurement of pain intensity in the low back pain patient.

Adult↗
PubMed1990

Emmert's law in the Ames room.

The Ames distorted room illusion, in which the perceived sizes of objects placed within the room differ from their objective sizes, has been used to support arguments for indirect perception. A study is reported in which Emmert's law of the apparent size of after-images was examined in relation to the Ames room's illusory alteration of apparent and actual distances. Size judgments of afterimages projected into the Ames room were compared with control conditions in which both actual and apparent afterimage projection distances were reproduced. Results indicate that Emmert's law may not provide a simple geometrical relationship between proximal image size and actual viewing distance, and that the processes involved in making afterimage size judgments are similar to those processes involved in making size judgments of 'real world' objects.

Adult↗
PubMed1989

Lateralized dual-task performance: the effects of spatial and muscular repositioning.

In three experiments subjects were required to perform different manual tapping tasks using either the left or right hand while concurrently performing a speech task. The major independent variables examined were muscular effort and the spatial and muscular repositioning components of the tapping tasks. In all speech conditions right hand performance was disrupted more than left hand performance. The degree of this lateralized disruption did not alter as a function of variation in either muscular effort or the repositioning requirements of the manual task. However, muscular repositioning activity, unlike other components of the motor task, was affected bilaterally by the addition of the speech task. Overall the results suggest that the dual-task procedure can be used to assess two types of "lateralized" interference effects; one relating to right hand performance, the other to left hemisphere performance.

Adult↗
PubMed1989

A dual-task study of sex differences in language reception and production.

The notion that females may be less lateralized than males for language reception was tested using a variant of the dual-task technique with 20 normal right-handed subjects. A unimanual tapping task was paired with one language reception task, and two language production tasks (one purely cognitive and the other requiring both cognitive and vocal involvement). Performance was impaired in all treatment conditions, regardless of hand used. Most impairment was, however, found in right-hand performance during the vocal condition. No sex differences were found.

Female↗
PubMed1989

Lateralised dual-task performance: the effect of muscular-repositioning.

In two experiments subjects performed tapping tasks requiring different degree of muscular repositioning while concurrently performing a speech task. In all concurrent speech conditions right-hand performance was disrupted more than left-hand performance, but the degree of this differential disruption did not alter as a function of the muscular repositioning requirements of the dual-tasks. It was concluded that rapid muscular repositioning does not appear to be the source of lateralised interference effects observed in concurrent task studies. However, it may be argued that some minimum level of repositioning is required, particularly if the differential effect reflects a lateralisation of "kind" rather than of "degree". This needs further research. One relevant factor proposed here which may alter the degree of lateralised effects is the degree of muscular effort required to perform each of the dual-tasks.

Adult↗
PubMed1989

Tactile perceptual asymmetry: the influence of motor activity and imagery instructions.

The purpose of this study was to examine the degree to which changes in muscular activity modify tactile perceptual asymmetries. In two experiments subjects were presented with a series of pairs of random shapes to the fingers of each hand. Their task was to detect the occurrence of a previously learnt target shape. Pressing on to the shape was the only movement allowed and other types of motor activity, particularly tracing movements, were not permitted. Across experimental conditions subjects were required to change the pressure and hence muscular effort used to press upon the shape. A left-hand advantage was found across all experimental conditions and its size did not change when subjects were required to press either firmly or lightly upon the shapes. This result was also found when subjects were required to apply uneven pressure between the hands. One-half of the subjects also performed the experimental conditions following instructions to use imagery. This produced an enhancement of right-hand performance on the task with a loss of the left-hand advantage. The results suggest that observed tactile perceptual asymmetries, while unaffected by changes in muscular effort, are easily overridden by higher-order cognitive and motor processes.

Adult↗
PubMed1986

Is an accurate verbal language necessary for heart rate discrimination?

Three groups of subjects were required to discriminate levels of cardiac function over three sessions. Two groups were required to detect in which of two contiguous 4-sec periods their heart rate (HR) was slowest. One of these groups was given knowledge of results concerning the correctness of their decisions. Their performance improved significantly. The other group was not given knowledge of results and their performance hovered around chance level. The third group was told to detect the period in which their heart rate was fastest, but they were told 'correct', via knowledge of results, only if they had picked their slowest rate. Their performance was inferior to the knowledge of results group, but superior to the no-knowledge group. They showed, however, little evidence of improved performance over sessions. The results are discussed in terms of a verbal labelling control of required discriminations.

Adult↗
PubMed1984

Heart rate discrimination and heart rate control: a test of Brener's theory.

Three experiments were conducted to examine predictions from Brener's theory regarding the relationship between autonomic discrimination and autonomic control. Experiment 1 examined the possibility that training subjects to discriminate their heart rates would enhance their skill at controlling that response. Twenty subjects participated in two sessions during which one group of 10 subjects received training (knowledge of results) on the Ashton discrimination technique. The second group performed the discrimination task but received no training. All subjects then took part in a third session of heart rate (HR) control (both increase and decrease) where half of each of the aforementioned groups received feedback during the control task, while the other half performed the HR control task without feedback. Results indicated that for the control of both HR increases and decreases, there was no significant difference between those subjects trained to discriminate their HR, and those who had received no training to discriminate HR. The second experiment investigated the hypothesis that training subjects with feedback to control their HR would enhance their capacity to discriminate their heart activity. Ten subjects participated in two sessions of HR control during which half the subjects received feedback training to increase HR. During a third session, all subjects underwent a test of discrimination ability using the Ashton technique, and no knowledge of results regarding performance was provided. Results confirmed the hypothesis. The final experiment in the series investigated the discrimination/control relationship within a problem-solving framework and used 20 subjects. Results confirmed the hypothesis that subjects forewarned at the time of discrimination training that a heart rate control task was to follow would perform better than 10 subjects receiving no forewarning of the task objective. This effect took place independently of cardiac discrimination ability. A second finding from this experiment was that subjects trained to discriminate heart rate were better able to increase heart rate than untrained subjects. This result contradicts that of Experiment 1, and reasons for this anomaly are discussed in detail.

Adolescent↗