COGNITIVE ASPECTS OF DIFFERENCE TESTING: MEMORY AND INTERSTIMULUS DELAY

There are many ways in which a laboratory difference test differs from 'real life' discrimination of foods. One of these is the interval of time between tasting the two stimuli to be discriminated. To investigate this, judges performed same-different discrimination tests using a citrus flavored beverage as a medium. The time interval between tasting the standard and comparison stimuli was varied. In this initial study, short intervals of zero, 30, 60 s were examined. For judges unfamiltar with the stimuli, performance deteriorated as the time interval increased. For judges familiar with the stimuli, the zero time interval elicited best performance but there was no decrease in performance when the interval was increased from 30 to 60 s. The results were explained by hypothesizing different types of memory trace for the standard stimulus being utilized for comparison with the comparison stimulus.     

Direct Action of Insulin on Plasma Membrane ATPase Activity in Human Lymphocytes

LITTLE is known about the effects of insulin on lymphocytes. Helmreich and Eisen¹ concluded that it has insignificant effects, but others^2–5 have made a case for a role in inflammatory and immunological responses. We^6,7 have demonstrated that noradrenaline enhances the uptake of both glucose and potassium by lymphocytes, as does insulin in several tissues. We have associated this action of noradrenaline with a direct effect on membrane adenosine triphosphatase (ATPase) activity⁷. The observation⁸ that insulin bound to ‘Sepharose’ polymers enhances glucose transport while in contact only with the plasma membrane indicated that insulin might have a direct action similar to that of noradrenaline on membrane ATPase. The observations reported here show that insulin stimulates ATPase activity and glucose uptake in the lymphocyte and suggest a relationship between membrane ATPase activity and glucose transport.     

Multivariate analysis of the Vicia sativa L. aggregate

GIL, J. & CUBERO, J. I., 1993. Multivariate analysis of the Vicia sativa L. aggregate . The sativa group of species was studied by using multivariate analysis and karyological analysis. Thirty biometrical characters were studied by using 92 Vicia sativa L. accessions from a variety of geographical sources. The four main taxa analysed were: sativa, macrocarpa, cordata and angustifolia. Principal component analysis provided clear separation among sativa, cordata and angustifolia in terms of the first two components. Karyotype analysis confirmed the PCA results, and by combining both methods, misclassed specimens can be correctly determined. Cluster analyses using the characters which displayed the greatest loads over the first components were performed in order to identify the most valuable characters from the taxonomic point of view. These were flower length, calyx length, pod width, constriction of the pod between seeds, leaf length, leaflet width, seed length and seed width. Our results suggest an early separation of angustifolia from the ancestral stem. The taxon cordata may be useful in future plant breeding programmes not only for crossing with V. saliva to increase the leaflet size of this taxon, but also as a bridge species between sativa and angustifolia.     

SAME-DIFFERENT DISCRIMINATION TESTS WITH INTERSTIMULUS DELAYS UP TO ONE DAY

There are many ways in which a laboratory difference test differs from 'real life'discrimination of foods. One of these is the interval of time between tasting the two stimuli to be discriminated. To investigate this, Cubero et al. (1995) investigated interstimulus delays of up to 1 min. for the same-different test, using a citrus flavored beverage as a medium. The present study extended this research by increasing the interstimulus delays up to 1 day. For judges unfamiliar with the stimuli, performance deteriorated as the time interval increased. For judges more familiar with the stimuli, performance deteriorated but not as much. The results were compatible with Cubero et al.'s hypothesis that different types of memory trace for the first (standard) stimulus were utilized for comparison with the second (comparison) stimulus.