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L M Ward

Publications and source records attributed to L M Ward.

At least 19 recordsLinked to original sources
PubMed1992

Intensity and frequency resolution: masking of absolute identification and fixed and roving discrimination.

Auditory intensity and frequency resolution were studied in three paradigms under masking conditions. Absolute identifications of single stimuli (one-interval paradigm) and 2IFC judgments of fixed- and roving-level pairs of stimuli (two-interval paradigm) were obtained from the same experienced observers. Judgments were made under optimal (no mask) conditions, in the presence of a broadband noise mask (simultaneous mask), and when the stimulus(i) to be judged were either preceded (forward mask) or followed (backward mask) by a broadband noise mask. Substantial masking of intensity resolution was found in all mask conditions. Only a simultaneous mask affected frequency resolution. In the no mask condition, performance was best for fixed-level (or frequency) 2IFC discrimination, followed by roving-level (frequency) 2IFC, and finally absolute identification. These differences were maintained under masking for frequency resolution, but not for intensity resolution. The results are discussed in terms of the Braida and Durlach (1988) model of intensity resolution. A similar model is suggested for frequency resolution with differences suggested by the differences in neural coding of sound intensity and frequency.

Auditory Perception↗
PubMed1992

Rheumatoid cachexia: depletion of lean body mass in rheumatoid arthritis. Possible association with tumor necrosis factor.

OBJECTIVE: To investigate body composition and serum tumor necrosis factor (TNF) levels in a series of 24 patients with rheumatoid arthritis (RA). METHODS: Body composition assessment by anthropometric measures and bioelectrical impedance. Cytokine determination in serum by ELISA: RESULTS: When compared to United States population norms, 16 of the subjects (67%) were cachectic. In regression models, lean body mass (LBM) was inversely associated with the number of swollen joints (p < 0.025). Elevated TNF-alpha was found in 3 of 5 flaring patients vs 0 of 18 patients with less active disease (p = 0.001). These 3 were all cachectic, while the 2 flaring patients without detectable TNF had normal LBM (p < 0.03). Among the whole group, there was a trend toward increasing disability with decreased LBM after adjusting for joint pain and disease duration (p < 0.07). CONCLUSION: Cachexia is common in RA, and may be cytokine driven. Given the prognostic impact of LBM wasting in other diseases, the effect of rheumatoid cachexia on outcome in RA deserves further study.

Adult↗
PubMed1991

Absence of human papilloma virus in cervical adenocarcinoma determined by in situ hybridisation.

A few studies using DNA technology have suggested that human papillomavirus (HPV) may be an aetiological factor for adenocarcinoma of the uterine cervix. Twenty one cases of cervical adenocarcinoma were studied by in situ hybridisation using biotinylated DNA probes for HPV types 6, 11, 16 and 18 and a streptavidin, biotinylated alkaline phosphatase detection system. Intranuclear HPV DNA was detected in none of the adenocarcinomas, while positive controls gave a clear intranuclear signal. Adjacent areas of normal, koilocytic, and dysplastic squamous epithelium also gave positive results. It may be that squamous epithelium contaminates adenocarcinomas reported as positive by Southern blotting. Our results showing absence of detectable HPV DNA within adenocarcinomas suggest that HPV infection may not have a major role in the aetiology of adenocarcinoma of the uterine cervix.

Adenocarcinoma↗
PubMed1991

Informational and neural adaptation curves are asynchronous.

Norwich's entropy theory of perception (plus a few additional assumptions) suggests the existence of an "infromational adaptation curves" (change in stimulus equivocation with stimulus duration) for suprathreshold prothetic stimuli that is synchronous with the "neural adaptation curve" (change in firing rate with stimulus duration) observed for sensory neurons. Five experiments are reported in which informational adaptation curves were measured for auditory and visual stimuli by having subjects make absolute identifications of suprathreshold sound or light intenstiies of various durations. Information transmissions for the shortest duration stimuli (1 and 5 msec, respectively, for light and sound) were surprisingly large (small equivocations), indicating that intensity information is acquired very rapidly by the whole organism. The equations of entropy theory were fitted to adaptation data for peripheral sensory neurons (spiral ganglion cells and retinal ganglion cells) and were compared to the informational adaptation curves. It was found that informational adaptation occurred more rapidly than neural adaptation. That is, the two types of adaptation process are asynchronous. However, for both audition and vision, the total amount of information mediated by the adaptation process (channel capacity) was about the same for both types of processes (2.03 bits vs. 2.1 bits per stimulus for sound intensity; 1.3 vs. 2.0 bits per stimulus for light intensity). Faster acquisition could be accomplished in the whole organism through convergent neural circuits that increase sampling rate by pooling the samples taken by individual receptor systems.

Adult↗
PubMed1990

Cross-modal additive conjoint structures and psychophysical scale convergence.

I investigated a variety of issues related to the measurement of the magnitude of psychological experience, especially the magnitude of sensations. Different groups of subjects made pair comparisons, magnitude estimations, and category judgments of the "total sensory magnitude" of light and sound stimuli presented conjointly. Another group judged the dissimilarity of pairs of conjoint stimuli. Various axioms, especially double cancellation, were tested on the resulting rank orders of conjoint stimuli. Judgements of the total magnitude of conjoint combinations of sound and light stimuli formed an additive conjoint structure. Dissimilarity judgments gave rise to a closely related lattice structure. Moreover, various scales of the individual attributes (loudness and brightness) calculated from the two types of judgments of the conjoint stimuli displayed substantial convergence, each scale for a given modality being linear with all other scales for that modality.

Adult↗
PubMed1990

Unmasking the magnitude estimation response.

The fuzzy judgement model of Ward (1979) predicts an inverse relation between the amount of stimulus information available to subjects and the magnitude of sequential dependencies on previous stimuli and responses in psychophysical scaling tasks. Ward confirmed this prediction for magnitude estimations of interdot distance for previous responses but not for previous stimuli, although the inverse relation has been repeatedly reported for both the previous stimuli and responses in absolute identification (e.g., Mori, 1989). This paper further explores this seemingly puzzling contradiction. A magnitude estimation of loudness experiment was conducted in which the amount of stimulus information available to subjects was manipulated by a modified version of informational masking (Watson, 1987). An absolute-identification-with-feedback experiment was also conducted to check the effectiveness of the informational masking in reducing the amount of stimulus information. The results of the magnitude estimation experiment show a striking similarity with those of Ward and generalize the failure of sequential dependencies on previous stimuli to vary inversely with stimulus information. An additional assumption that judgement strategies are altered under low-information conditions is necessary to explain this result.

Feedback↗
PubMed1990

Catabolic effects of high-dose corticosteroids persist despite therapeutic benefit in rheumatoid arthritis.

Although corticosteroids (CS) cause nitrogen wasting in healthy humans, it is not known whether the salutary antiinflammatory and appetite-stimulating effects of CS in inflammatory diseases mitigate this effect. We measured nitrogen balance before, during, and after 3 d of high-dose methylprednisolone therapy in nine patients with flare-ups of rheumatoid arthritis. There was evidence of preexisting somatic protein and fat depletion in seven of nine subjects. Patients were allowed to eat freely on a metabolic ward. Nitrogen balances were -0.89 +/- 1.38 g/d (means +/- SEM) before CS therapy, -5.77 +/- 1.30 g/d during therapy (P less than 0.001), and -3.54 +/- 1.38 g/d after therapy (P less than 0.01) despite increased energy and nitrogen intake and clinical resolution of inflammation during and after the pulse therapy. We conclude that patients with rheumatoid arthritis are often cachectic and high-dose CS cause nitrogen wasting in these patients despite an antiinflammatory and appetite-stimulatory benefit.

Adrenal Cortex Hormones↗
PubMed1990

Vitreous fluorophotometry in patients with Best's macular dystrophy.

Ten patients with Best's macular dystrophy were examined with vitreous fluorophotometry and results were compared with a normal population. Seventeen of the 20 affected eyes demonstrated an intact blood-retinal barrier with normal inward permeability of fluorescein dye. Despite diffuse functional impairment of the retinal pigment epithelium (RPE), determined by electro-oculography, as well as accumulation of a lipofuscin or lipofuscin-like substance within virtually all RPE cells, the blood-retinal barrier function of these cells remained intact as determined by clinical fluorophotometry. Similar findings have previously been noted in another hereditary retinal disorder (fundus flavimaculatus) in which a lipofuscin-like substance also accumulates diffusely within RPE cells.

Adolescent↗
PubMed1990

Critical bands and mixed-frequency scaling: sequential dependencies, equal-loudness contours, and power function exponents.

Stimuli of random intensities and various but predictable frequencies were presented for repeated magnitude estimations on the same scale (mixed-frequency scaling). The frequencies for a particular judgment session were selected so that they lay either inside each other's critical bands or outside them. Contrastive dependencies of current magnitude estimation responses on previous stimuli of a different frequency were significantly affected by whether the two frequencies were inside or outside each other's critical bands, while assimilative dependencies were not. This reinforces the idea that such dependencies are sensory in nature and arise from a different mechanism than do the assimilative dependencies. Mixed-frequency scaling of loudness also gives rise to cross-frequency matching functions from which equal-loudness contours can be calculated. These contours calculated from the present judgments are similar to those produced from other methods, even when they are extrapolated to untested intensities. Power function exponents for loudness scaled in this way are larger for lower frequencies, as has been found in previous studies, and are consistent with the flattening of the calculated equal-loudness contours for low frequencies as intensity increases.

Adult↗
PubMed1990

Mixed-method mixed-modality psychophysical scaling.

Four experiments are reported in which the direct psychophysical scaling methods of magnitude estimation, category judgment, and cross-modality matching were mixed in the same series of trials, both with a single stimulus modality and in a mixed-modality situation. The mixed-method scaling situation gave results consistent with those obtained when methods are used alone, and it has several advantages. Interactions between the methods were consistent with the idea that judgments made under all three are mediated by a primitive process of categorization that is influenced by heuristics used to achieve a single category identity for each stimulus.

Adult↗
PubMed1987

On evolutionary systems.

This paper develops a metatheoretical framework for understanding evolutionary systems (systems that develop in ways that increase their own variety). The framework addresses shortcomings seen in other popular systems theories. It concerns both living and nonliving systems, and proposes a metahierarchy of hierarchical systems. Thus, it potentially addresses systems at all descriptive levels. We restrict our definition of system to that of a core system whose parts have a different ontological status than the system, and characterize the core system in terms of five global properties: minimal length interval, minimal time interval, system cycle, total receptive capacity, and system potential. We propose two principles through the interaction of which evolutionary systems develop. The Principle of Combinatorial Expansion describes how a core system realizes its developmental potential through a process of progressive differentiation of the single primal state up to a limit stage. The Principle of Generative Condensation describes how the components of the last stage of combinatorial expansion condense and become the environment for and components of new, enriched systems. The early evolution of the Universe after the "big bang" is discussed in light of these ideas as an example of the application of the framework.

Biological Evolution↗
PubMed1987

Remembrance of sounds past: memory and psychophysical scaling.

What is the role of long-term memories of previous stimulus-response mappings, and of previous sensory and perceptual experiences generally, in psychophysical scaling judgments? I conducted four experiments in an attempt to provide some preliminary answers to this question. In each experiment, subjects made judgments of the loudness of sounds on 3 successive days. Stimulus intensities were drawn randomly from the same set on Days 1 and 3 but from a different set, either all 12 dB higher or all 12 dB lower, on Day 2. Four different types of psychophysical scaling judgments were studied: category judgment without an experimenter-induced identification function, ratio magnitude estimation with a variable standard, absolute magnitude estimation, and cross-modality matching. The first two methods required completely relative judgment, the last two completely absolute judgment. Data from all methods reveal profound effects of stimulus-response mappings experienced on previous days (long-term memory) and immediately previous stimuli and responses (short-term memory) on responses to current stimuli. Responses were typically a compromise between absolute and relative judgment. Individual differences were dramatic.

Female↗
PubMed1987

Antiphospholipid antibodies associated with retinal vascular disease.

Two patients with retinal vascular disease also had antiphospholipid antibodies, defined by the presence of the circulating lupus anticoagulant (LAC), anticardiolipin antibodies, or both. One had retinal arterial occlusions and the other had a nonischemic central retinal vein occlusion. The association of thrombotic vascular disease, including both retinal and cerebral vessels, with the presence of these antibodies should be investigated in otherwise normal individuals or in patients presenting with a lupuslike syndrome and retinal vascular occlusive disease. Low-dose aspirin administration could be of therapeutic value in managing thrombotic events in this group of patients.

Adult↗
PubMed1986

The relationship between articulation disorders and motor coordination in children.

This study was designed to examine the relationship between articulation disorders, soft neurological signs, and motor abilities. Fifteen children with articulation problems, as measured by the Templin-Darley Articulation Screening Test and a connected speech sample, were compared with a normal control group (matched for sex and age) on the Quick Neurological Screening Test, the Imitation of Postures test (from the Southern California Sensory Integration Tests), and the 1984 version of the Stott Test of Motor Impairment that has been revised by Henderson. A significant difference was found between the groups on the Motor Impairment Test and the Quick Neurological Screening Test, supporting the hypothesis that the articulation disorder children would have more motor coordination problems and soft neurological signs than the normal children in the control group. There was no between-group difference on the Imitation of Postures test, suggesting that as a group, children with articulation deficits are not dyspraxic. This study supports other research findings stating a relationship between articulation problems and motor impairment, but it also indicates that this motor impairment is not necessarily dyspraxia.

Articulation Disorders↗