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Biomedical subjects

G V Jones

Publications and source records attributed to G V Jones.

14 recordsLinked to original sources
PubMed1992

Modulation of plasma aldosterone by physiological changes in hydrogen ion concentration.

To assess the effect of extracellular hydrogen ion concentration (PH+) on aldosterone secretion, studies in which other known modulators could be controlled were performed on 13 patients undergoing hemodialysis. High (35 mM) or low (14-17 mM) dialysate bicarbonate concentrations were utilized on separate days to either decrease or increase PH+, while plasma potassium concentrations (PK) were held at constant levels and changes in plasma renin activity (PRA) were minimized by avoiding changes in body weight. Changes in PH+ were associated with concordant changes in plasma aldosterone concentration (Pa) in both high- and low-bicarbonate studies. When these changes in Pa in high- and low-bicarbonate studies were analyzed together as a function of corresponding changes in PH+, a significant correlation could be demonstrated (r = 0.659, P less than 0.001). There was no correlation between changes in Pa and changes in PK, plasma sodium, plasma adrenocorticotropic hormone (ACTH), or PRA. Using the same methods to control PH+ and other variables during hemodialysis, the effects of altered PH+ on ACTH-stimulated aldosterone and cortisol secretion were evaluated in studies on six patients who received incremental infusions of ACTH after pretreatment with dexamethasone. In these studies, there was no demonstrable effect of PH+ on Pa or plasma cortisol concentration. We conclude that physiological changes in PH+ have a weak modulating effect on basal aldosterone secretion that may not be evident in the presence of other acutely applied stimuli.

Adrenocorticotropic Hormone↗
PubMed1992

Misremembering a familiar object: mnemonic illusion, not drawing bias.

It was reported by Jones (1990) that the design of British coins is systematically misremembered. Although the Queen's head in fact faces right, most people draw it facing left. It is possible, however, that the origin of this phenomenon does not reside in memory but instead in a leftward drawing bias. Two experiments of the three reported here tested this hypothesis. In Experiment 1, British participants attempted to recall the direction of the Queen's head but responded verbally instead of pictorially. The results were similar to those of Jones and thus contradict the hypothesis that misremembering of the Queen's head is caused by a leftward drawing bias. In Experiment 2, Canadian participants attempted to draw a Canadian coin. Leftward misremembering was not observed in this case. Thus the hypothesized importance of a leftward drawing bias was again not supported. Instead, the results provided support for the schema explanation of the Queen's Head memory illusion proposed by Jones. The results of Experiment 3, which compared memory for British coins and stamps, further bolstered this conclusion.

Adolescent↗
PubMed1990

Misremembering a common object: when left is not right.

Three experiments were carried out to investigate people's memory for British coins. Two principal issues were studied. First, it has previously been shown that memory for U.S. pennies and other coins is surprisingly imperfect. How do other countries compare? It turned out that recall of the design of British pennies was, if anything, worse even than that of U.S. pennies. The situation was no better for a larger coin with an unusual shape. It is suggested that individual features are poorly remembered if they have low levels of meaningfulness, redundancy, identifiability, and discriminativeness. Second, in addition to this generally weak level of remembering, an instance of systematic misremembering was consistently observed. The Queen's portrait always faces to the right on British coins. Yet in all three experiments, the proportion of participants who recalled that the portrait faces to the right was so low (overall, 19%) that it was significantly less than even the 50% baseline to be expected from people in a state of complete ignorance. It follows that the participants were not in a state of complete ignorance. Rather, they relied upon extraneous knowledge of either a general or a specific nature (bias and schema hypotheses, respectively), whose importation into this domain was in fact invalid. The resulting belief that coin portraits face left was not right.

Attention↗
PubMed1989

Back to Woodworth: role of interlopers in the tip-of-the-tongue phenomenon.

When a person reports that a word is on the tip of his or her tongue, that person often recalls instead another word that is similar in sound to the target word. Two opposite roles have been suggested for these interlopers. An older view (Woodworth, 1929) holds that they are instrumental in the development of tip-of-the-tongue (TOT) states because they obstruct successful retrieval of intended targets. A more recent view (R. Brown & McNeill, 1966) holds, on the other hand, that interlopers tend to nullify TOT states by facilitating complete retrieval of the intended targets. A study is reported in which participants were explicitly presented with interloper words. The results provide two planks of support for Woodworth's hypothesis. First, more TOT states occurred when the interloper was similar in sound to the target than when it was not. Second, more TOT states occurred when the interloper was presented at the actual time of retrieval than when it was presented earlier. It appears that interlopers tend to induce TOT states by obstructing retrieval, rather than to nullify them by facilitating retrieval.

Attention↗
PubMed1985

Deep dyslexia and the right-hemisphere hypothesis for semantic paralexia: a reply to Marshall and Patterson.

Studies of deep dyslexia have conferred prominence upon observations of semantic paralexia (e.g. reading "town" as "city"). Landis et al. (Neuropsychologia 21, 359-364, 1983) have reported evidence indicating that such errors arise in the right hemisphere. However, Marshall and Patterson (Neuropsychologia 21, 425-427, 1983) have advanced both empirical and theoretical arguments against this interpretation: the present paper examines these arguments and finds them seriously flawed. It therefore concludes in favour of the right-hemisphere hypothesis for semantic paralexia.

Dominance, Cerebral↗
PubMed1985

Deep dyslexia, imageability, and ease of predication.

A development of existing theories of deep dyslexia is outlined. It proposes that the effects of imageability upon the ease of reading of words by deep dyslexics occur as a result of variation in the ease with which individual words summon semantic predicates, on the basis of which reading responses can be made. Ease-of-predication scores are obtained for a corpus of nouns and found to be, as hypothesized, closely related to imageability scores. It is shown that the other major characteristics of deep dyslexia can also be accounted for by this proposed mechanism. These include the well-established effects of syntactic category (in particular, of the distinction between content and function words) upon reading. Further evidence is provided that this effect may be attributed to variation in ease of predication.

Dyslexia↗
PubMed1983

On double dissociation of function.

In this note, the important neuropsychological paradigm of double dissociation is reviewed. It is suggested that it may be useful to view double dissociation as a type of crossover interaction. Implications of this view for conceptual and statistical analysis are briefly discussed.

Brain↗
PubMed1979

Negative recency and measurement of primary memory.

The technique of Waugh & Norman (1965) is widely used in measuring the capacity of primary memory. Watkins (1974) has proposed a modification of the technique which takes into account registration failure. A further modification is proposed which takes into account findings of negative recency in delayed recall.

Humans↗