The effect of interstimulus interval on sequential effects in absolute identification

In absolute identification experiments, the participant is asked to identify stimuli drawn from a small set of items which differ on a single physical dimension (e.g., 10 tones which vary in frequency). Responses in these tasks show a striking pattern of sequential dependencies: The current response assimilates towards the immediately preceding stimulus but contrasts with the stimuli further back in the sequence. This pattern has been variously interpreted as resulting from confusion of items in memory, shifts in response criteria, or the action of selective attention, and these interpretations have been incorporated into competing formal models of absolute identification performance. In two experiments, we demonstrate that lengthening the time between trials increases contrast to both the previous stimulus and the stimulus two trials back. This surprising pattern of results is difficult to reconcile with the idea that sequential dependencies result from memory confusion or from criterion shifts, but is consistent with an account that emphasizes selective attention. </jats:p

The effect of stimulus range on two-interval frequency discrimination

It has traditionally been thought that performance in two-interval frequency discrimination tasks decreases as the range over which the standard tone varies is increased. Recent empirical evidence and a reexamination of previous results suggest that this may not be the case. The present experiment found that performance was significantly better when the standard roved over a wide range (1500 Hz) than a narrow range (30 Hz). This pattern cannot readily be accommodated by traditional models of frequency discrimination based on memory or attention, but may be explicable in terms of neural plasticity and the formation of perceptual anchors

Psychophysics and the judgment of price: judging complex objects on a non-physical dimension elicits sequential effects like those in perceptual tasks

When participants in psychophysical experiments are asked to estimate or identify stimuli which differ on a single physical dimension, their judgments are influenced by the local experimental context — the item presented and judgment made on the previous trial. It has been suggested that similar sequential effects occur in more naturalistic, real-world judgments. In three experiments we asked participants to judge the prices of a sequence of items. In Experiment 1, judgments were biased towards the previous response (assimilation) but away from the true value of the previous item (contrast), a pattern which matches that found in psychophysical research. In Experiments 2A and 2B, we manipulated the provision of feedback and the expertise of the participants, and found that feedback reduced the effect of the previous judgment and shifted the effect of the previous item’s true price from contrast to assimilation. Finally, in all three experiments we found that judgments were biased towards the centre of the range, a phenomenon known as the “regression effect” in psychophysics. These results suggest that the most recently-presented item is a point of reference for the current judgment. The findings inform our understanding of the judgment process, constrain the explanations for local context effects put forward by psychophysicists, and carry practical importance for real-world situations in which contextual bias may degrade the accuracy of judgments

The application of experimental data to blade wake interaction noise prediction

Blade wake interaction noise (BWI) has been defined as the broadband noise generated by the ingestion of turbulent trailing tip vortices by helicopter rotors. This has been shown to be the dominant contributor to the subjectively important part of the acoustic spectrum for the approach stage of a helicopter flyover. A prediction method for BWI noise based on the calculated trailing vortex trajectories has been developed and estimates of the vortex turbulence have been made. These measurements were made on a trailing vortex from a split wing arrangement and did not give the spectrum of the velocity fluctuations. A recent experiment carried out to measure the turbulence associated with a trailing vortex and the application of the results to BWI noise prediction is described

Efficacy, safety, and improved tolerability of travoprost BAK-free ophthalmic solution compared with prior prostaglandin therapy

J Charles Henry1, James H Peace2, Jeanette A Stewart3,4, William C Stewart3,41Little Rock Eye Clinic, Little Rock, AR, USA; 2Diabetic Eye Medical Clinic, Inglewood, CA, USA; 3PRN Pharmaceutical Research Network, LLC, Dallas,TX, USA; 4Carolina Eye Institute, University of South Carolina, School of Medicine, Columbia, SC, USAPurpose: To evaluate the efficacy, safety and tolerability of changing to travoprost BAK-free from prior prostaglandin therapy in patients with primary open-angle glaucoma or ocular hypertension.Design: Prospective, multi-center, historical control study.Methods: Patients treated with latanoprost or bimatoprost who needed alternative therapy due to tolerability issues were enrolled. Patients were surveyed using the Ocular Surface Disease Index (OSDI) to evaluate OSD symptoms prior to changing to travoprost BAK-free dosed once every evening. Patients were re-evaluated 3 months later.Results: In 691 patients, travoprost BAK-free demonstrated improved mean OSDI scores compared to either latanoprost or bimatoprost (p&amp;nbsp;&amp;lt; 0.0001). Patients having any baseline OSD symptoms (n = 235) demonstrated significant improvement after switching to travoprost BAK-free (p&amp;nbsp;&amp;lt; 0.0001). In 70.2% of these patients, symptoms were reduced in severity by at least 1 level. After changing medications to travoprost BAK-free, mean intraocular pressure (IOP) was significantly decreased (p &amp;lt;&amp;nbsp;0.0001). Overall, 72.4% preferred travoprost BAK-free (p &amp;lt; 0.0001, travoprost BAK-free vs prior therapy). Travoprost BAK-free demonstrated less conjunctival hyperemia than either prior therapy (p &amp;lt;&amp;nbsp;0.0001).Conclusions: Patients previously treated with a BAK-preserved prostaglandin analog who are changed to travoprost BAK-free have clinically and statistically significant improvement in their OSD symptoms, decreased hyperemia, and equal or better IOP control.Keywords: glaucoma, prostaglandin analog, travoprost, latanoprost, bimatoprost, preservative, benzalkonium chloride, ocular surface diseas

Efficacy, safety, and tolerability of travoprost 0.004% BAK-free versus prior treatment with latanoprost 0.005% in Japanese patients

Michael J Miyashiro1, Samuel C Lo2, Jeanette A Stewart3, William C Stewart31Ludwig Ophthalmology Centre, Hilo, HI, USA; 2Private Practice, Honolulu, HI, USA; 3PRN Pharmaceutical Research Network, LLC, Dallas, TX, USAObjective: To examine the efficacy, safety, and tolerability of travoprost 0.004% benzalkonium chloride (BAK)-free compared with previous use of latanoprost 0.005% in Japanese patients living in the US who had primary open-angle glaucoma or ocular hypertension.Methods: This was an open-label, multicenter, bilateral, intraindividual, and active-controlled study in which 20 Japanese American patients with primary open-angle glaucoma or ocular hypertension who had been on latanoprost 0.005% monotherapy were changed to monotherapy with travoprost 0.004% BAK-free daily for 12 weeks. Patients were administered the same series of tests to evaluate the efficacy, safety, and tolerability of latanoprost at the baseline visit and of travoprost BAK-free at the week 12 visit.Results: No significant difference in mean intraocular pressure (IOP) was observed between latanoprost monotherapy at baseline and travoprost BAK-free monotherapy after 12 weeks (P = 0.76), nor were significant differences noted in mean ocular hyperemia, visual acuity, corneal fluorescein staining, or overall scores from the Ocular Surface Disease Index. Patients had a significantly shorter mean tear breakup time while on latanoprost compared with travoprost BAK-free (P = 0.0094). Significantly more patients preferred travoprost BAK-free monotherapy over latanoprost monotherapy (14 versus 6; P = 0.011).Conclusion: The results of this study suggest that Japanese American patients transitioned from latanoprost 0.005% monotherapy to travoprost 0.004% BAK-free can expect similar IOP control and some improvement in anterior segment signs. This transition study showed a strong patient preference for travoprost BAK-free over latanoprost, at a ratio of more than 2:1.Keywords: glaucoma, intraocular pressure, latanoprost, prostaglandin analog, travopros

Flow structure generated by perpendicular blade vortex interaction and implications for helicopter noise predictions

Activities carried out in support of research on flow structure generated by perpendicular blade vortex interaction and implications for helicopter noise prediction are summarized. Progress in the following areas is described: (1) construction of 8 inch-chord NACA 0012 full-span blade; (2) Acquisition of two full-span blades; (3) preparation for hot wire measurements; (4) related work on a modified Betz's theory; and (5) work related to helicopter noise prediction. In addition, a list of publications based on the results of prior experimentation is presented