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Choice Procedures (choice + procedure)
Selected AbstractsPerceived blur in amblyopiaOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 6 2002A. J. Simmers Purpose:, It is well documented that visual acuity and contrast sensitivity in amblyopia are attenuated at high spatial frequencies: this would predict that amblyopes should perceive objects as blurred because they lack high spatial frequency information necessary to adequately represent sharp edges. In a series of experiments, we explored the representation of blur in amblyopia with blur discrimination and blur matching tasks. Methods:, Monocular blur discrimination thresholds were measured in a spatial 2-Alternative Force Choice procedure. The luminance profiles of the blurred edge were cumulative Gaussians with the standard deviation of the reference blurred edge being fixed at 1.88, 3.75, 7.5, 15, 30, or 60 min arc. Observers were required to discriminate which edge (right or left) appeared to be the less blurred. Observers also interocularly matched edges which were identical to those employed in the blur discrimination tasks, with the exception that they were viewed dichoptically at all times. Results:, Blur discriminination thresholds were elevated in both the amblyopic and fellow fixing eye but were within the normal range for interocular matching thresholds. Our results suggest that blur is veridically represented in the amblyopic visual system. Conclusions:, The surprising result here is that all amblyopes, even those with the most severe visual loss, veridically matched all blurred edges, including the sharpest ones. This implies that amblyopes are able to represent levels of blur that are defined by spatial structure beyond their resolution limit. These results also raise interesting questions about the mechanism by which blur is represented in the visual system. [source] Carisbamate, a Novel Antiepileptic Candidate Compound, Attenuates Alcohol Intake in Alcohol-Preferring RatsALCOHOLISM, Issue 8 2009Amir H. Rezvani Background:, Since 1994, when naltrexone (Revia®) was approved by the FDA for the treatment of alcoholism, only 2 other drugs (Campral® and Topamax®) have been approved for alcoholism treatment. However, various experimental drugs, including antiepileptic medications, have been tested in both animal models and in humans with some promising results. The purpose of this project was to study the effect of the novel neuromodulator carisbamate, which is in development for epilepsy treatment, on alcohol intake in selectively bred alcohol-preferring rats. Methods:, Male alcohol-preferring inbred P rats were allowed to freely drink water or alcohol (10%, v/v) using a 2-bottle choice procedure. After stable baselines for alcohol and water intakes were established, the acute effects of oral carisbamate (0, 10, 30, 45, 60, and 90 mg/kg) were assessed. Then, the chronic effect of the compound (60 mg/kg/day for 14 consecutive days) on alcohol intake was assessed in a separate group of male P rats. In another set of experiments, the effects of carisbamate and naltrexone on alcohol withdrawal-induced elevated drinking of alcohol, an index of craving, were compared. Rats were withdrawn from alcohol for 24 hours and were given vehicle, 20 mg/kg naltrexone or 60 mg/kg carisbamate 30 minutes before re-exposure to alcohol. Alcohol and water intake was measured 6 hours after alcohol re-exposure. To determine the effects of carisbamate on saccharin preference, rats were put on a 2-bottle choice of water versus a solution of 2% saccharin. Then, the effect of the highest dose of carisbamate (90 mg/kg) and naltrexone (20 mg/kg) and the vehicle on saccharin preference was determined. Results:, Our results showed that there was a selective dose-dependent reduction in alcohol intake and preference in the alcohol-preferring P rat after an acute oral administration of carisbamate. There were no significant effects on food or water intake. Chronic administration of carisbamate significantly reduced alcohol intake and preference initially, but partial tolerance developed after the 10th treatment. The degree of tolerance development was less than that observed for naltrexone. Acute administration of carisbamate was more effective than naltrexone in reducing enhanced alcohol intake after a period of alcohol deprivation. Compared with control vehicle neither carisbamate nor naltrexone had a significant effect on saccharin intake and preference. Conclusion:, The novel neuromodulator compound carisbamate has a favorable profile of effects on alcohol intake and related measures and should be considered for testing on human alcoholics. [source] THE POWER OF THE " A" -" NOT A" METHODJOURNAL OF SENSORY STUDIES, Issue 4 2001JIAN BI ABSTRACT The " A" - " Not A" method is a rating method with two categories. It is often treated as a discrimination method. Unlike forced choice procedures, the Thurstonian model for this method involves a choice criterion. In statistical tests, it is treated as a comparison of two proportions. In this paper, the power for hypothesis tests involving the monadic and replicated monadic " A" - " Not A" method is discussed. The power functions and the sample sizes needed for 80% power are given based on Thurstone's ,. Designs with equal and unequal allocations for A and A (Not A) samples are considered. The power of the method is also compared with that of four forced choice methods under the assumption that the perceptual variance is identical among methods. The comparison shows that, in general, the power for the five methods ranks from high to low: the 3-AFC, 2-AFC, " A" - " Not A", triangular and duo-trio. The comparison also shows that, based on the same number of panelists and/or the same sample size for the A and A, samples for the methods, if the panelists are not too discrepant and the choice criterion in the " A" - " Not A" method is not too strict or too lax, the power of the " A" - " Not A" method is very close to that of the 2-AFC method. [source] Increasing sales by introducing non-salable itemsMANAGERIAL AND DECISION ECONOMICS, Issue 8 2006Kobi Kriesler Rationality implies that adding ,irrelevant' and, in particular, inferior alternatives to the opportunity set cannot increase the choice probability of some other alternative. In this study, we propose a novel approach that can rationalize an intended addition of such alternatives because it strictly increases the choice probability of some existing alternative. The driving force behind the existence and extent of such an increase is the random nature of individual preferences, that implies intransitivity, and the random nature of the applied choice procedures. We study the case of a firm interested in increasing the sales of some of its existing products by introducing a new and inferior (non-salable) product. Our main results focus on the feasibility and potential advantage of a successful such strategy. We first establish necessary and sufficient conditions for an increase in the sale probability and then derive the maximal possible absolute and relative increase in this probability, when the firm has extremely limited information on the characteristics of the consumers. We then derive analogous results, assuming that the existing line of products consists of just two items and that the firm has accurate information on the consumers' stochastic preferences over the existing products. These later results are illustrated using some experimental evidence. The applicability of the approach is finally briefly discussed in the context of branding policy. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||