Presentation accuracy of Web animation methods.

Several Web animation methods were independently assessed on fast and slow systems running two popular Web browsers under MacOS and Windows. The methods assessed included those requiring programming (Authorware, Java, Javascript/Jscript), browser extensions (Flash and Authorware), or neither (animated GIF). The number of raster scans that an image in an animation was presented for was counted. This was used as an estimate of the minimum presentation time for the image when the software was set to update the animation as quickly as possible. In a second condition, the image was set to be displayed for 100 msec, and differences between observed and expected presentations were used to assess accuracy. In general, all the methods except Java deteriorated as a function of the speed of the computer system, with the poorest temporal resolutions and greatest variability occurring on slower systems. For some animation methods, poor performance was dependent on browser, operating system, system speed, or combinations of these.

Distance learning in graduate health administration education: a case study from Washington State University.

Some scholars have viewed distance learning as cause for concern, a potential degradation to the educational process. Others have said it provides the access that is not possible with traditional education and therefore expands the options for reaching diverse populations of students. Many are not certain where this educational toolis headed but know that it will have a big effect on the population of both students and faculty in educational institutions. Indeed, the direction of distance learning has the attention of many that previously attempted to ignore it as a passing trend in the educational process. Washington State University (WSU) at Spokane and its Health Policy and Administration (HPA) Program have been involved with distance education for more than a decade. The purpose here is to share this decade of experience. The academic and administrative experience of faculty, staff, and students are documented and discussed with the intent of showing both the advantages and disadvantages of distance learning. Some of the lessons learned are shared along with challenges in maintaining quality in the delivery of graduate education in health administration and other fields as we move forward in adopting distance learning tools and techniques.

Attentional momentum does not underlie the inhibition of return effect.

J. Pratt, T. M. Spalek, and F. Bradshaw (1999) recently proposed that attentional momentum is the mechanism underlying the inhibition of return (IOR) effect. They suggested that momentum associated with an attentional movement away from a peripherally cued location and toward an uncued opposite location is essential and fundamental to the finding of an IOR effect. Although it is clear from the present study and from a reanalysis of data from Pratt et al. that response time can be facilitated at an uncued opposite location, this putative effect of attentional momentum is neither robust nor reliable. First, it occurs for only a minority of participants. Second, it occurs in only a subset of the cued display positions. And finally, it is uncorrelated with the occurrence of IOR. Together the data indicate that the attentional momentum hypothesis is an overgeneralization and that it does not underlie the robust and reliable IOR effect.

Endogenous attention and illusory line motion reexamined.

P. Downing and A. Treisman's (1997) failure to replicate an effect of endogenous attention on the direction of illusory line motion (ILM) was reexamined. Four experiments with slightly modified stimulus presentation methods based on gradient theories of ILM found that endogenous attention directed to 1 of 2 similar priming objects is capable of influencing experienced motion direction within a subsequently presented line. The endogenous effect on ILM was consistent with a concomitant response-time discrimination task, was robust across naive and informed participants, occurred whether eye fixation was monitored or not, and occurred under conditions where multiple motion response categories were available to participants. The endogenous effect disappeared when participants moved their eyes to the attended item, when there was no motivation to endogenously attend, and when the presentation methods of P. Downing and A. Treisman (1997) were used.

Disinhibition of return: unnecessary and unlikely.

Recently, from data obtained with a temporal order judgment (TOJ) task, Gibson and Egeth (1994) concluded that inhibition of return (IOR; a response time effect that reveals slower responding to targets at previously cued versus uncued locations) reflects impaired perceptual processing. By replotting their data, we demonstrate that the perception of temporal order is influenced only by the facilitatory effect of a cue at short stimulus onset asynchronies (SOAs) and is unaffected by IOR at long SOAs. The target paper proposed that, when extra stimuli are presented at task-relevant locations (i.e., in the TOJ task), IOR is prevented by a hypothetical process that is known as disinhibition of return (DOR). We argue that the assumptions that IOR affects perceptual processing and that DOR exists are unnecessary, as a more parsimonious response-based interpretation of IOR is consistent with their data. Further, we summarize recent results and present new data that demonstrate that DOR is unlikely.

Multiple-location access in vision: evidence from illusory line motion.

Four experiments with undergraduates used illusory line motion (ILM) to contrast Z. W. Pylyshyn's (1989) FINST theory of spatial indexing with predictions made by unitary attention models. Multiple-onset stimuli were able to cause ILM at disparate, noncontiguous spatial locations. Consistent with gradient explanations of ILM and with FINST theory predictions, varying line-drawing speed and the number of stimuli revealed a decrease in ILM and a capacity limitation, respectively. Modeling analyses suggested a limit in the number of locations (5-7) that could elicit the illusion. Requiring participants to report the locations of all stimuli exhibiting illusory motion in a specified direction suggested parallel access to between 2 and 5 display locations simultaneously. The results of all 4 experiments were predicted by FINST theory but not by a broad class of unitary attention hypotheses.

Artificial looming yields improved performance over lateral motion: implications for stereoscopic display techniques.

In the natural world, a number of visual cues indicate that an item is quickly approaching the perceiver. Binocular disparity is one cue for depth, and it has been demonstrated that abrupt changes in disparity, artificially unaccompanied by correlated depth cues, are capable of causing the perception of looming for the observer. An experiment involving 38 undergraduates, using a computer-controlled stereoscopic display, examined the ability of above-threshold changes in disparity (artificial looming) to facilitate response time and accuracy for observers engaged in an object-enumeration task within a cluttered display. Compared with performance using the same stimuli without disparity information (lateral motion), participants were more accurate regardless of the disparity level (9, 12, 24, or 48 minutes of arc) and faster at the two lowest levels of disparity. Participants showed the classic subitizing function, suggesting that target stimuli presented with motion information were segregated from otherwise identical distractor items. It is proposed that binocular disparity information can act as a valid location cuing method in stereoscopic computer displays in which form and color information are to be preserved.

A spatial gradient of acceleration and temporal extension underlies three illusions of motion.

If an object (or cue), is presented and shortly afterwards a line is drawn with one end near to the object, motion away from the object location is induced within the line. This line-motion illusion has best been explained by postulating a facilitative spatial gradient that accelerates signal transmission most strongly near to the object, and less so with increasing distance away from the object. This simple accelerative-gradient model was tested in four experiments by either briefly presenting the line, or replacing the line rendering with a dot moving at high velocity towards (or away from) the initial object location. Observers first perceived motion away from the cue followed by motion towards the cue (hence this new illusion is referred to as the "two motion percepts", or TMP illusion). The generality of the TMP illusion was investigated through the reports of forty-five inexperienced undergraduates who were presented with TMP displays. Observers who were asked to pictorially reproduce their motion experience, drew a line expanding away from the cue then contracting back towards it 85% of the time. Over 90% of individuals reported experiencing the illusion with a quickly moving dot. The effects of several presentation parameters were investigated by the moving-dot method, and it was concluded that the accelerative-gradient model by itself was inadequate to explain TMP phenomena. Two extended versions of the gradient model are proposed that place the locus of the TMP effects in properties of motion detection mechanisms or in temporal aspects of visual-signal transmission.

"Inhibition of return' without visual input.

Inhibition of return (IOR) is the name that is associated with a response time (RT) delay to a visual stimulus presented at a recently cued spatial location. Two experiments with 26 undergraduates used an auditory analog to the visual IOR paradigm to examine whether manual RT inhibition would occur in the absence of visual input. In Experiment 1, subjects were instructed to prepare saccades, with their eyes closed, to the location of an auditory cue, and an RT delay to targets presented at the cued location was observed throughout the 1400 msec timecourse. Experiment 2 was used to examine the role of spatial distance between the auditory cue and the target, and found that as in the visual domain, there is a decrease in the magnitude of RT inhibition with increasing distance. Additionally, as in vision, support was found for the inhibition of targets presented in the same hemispace as the cue, whereas targets presented contralaterally were generally found to be facilitated. It was concluded that IOR is capable of acting in the auditory domain, and the possible neural origins of this effect are discussed. The result that IOR can occur even in the absence of visual input supports recent findings that perceptual representations of visual input are not the source of inhibition in this paradigm.

Inhibition of return is not detected using illusory line motion.

Inhibition of return (IOR) is the name that has been assigned to a response time (RT) delay to a stimulus presented at a recently stimulated spatial location. A commonly held explanation for the origins of IOR is that perceptual processing in inhibited and that this inhibition translates into slower RT. Three experiments with 10 subjects were used to directly test this perceptual explanation. The first two experiments assessed the level of perceptual facilitation present in the IOR paradigm using the frequency and latency of illusory line motion judgments. Contrary to the predictions of the perceptual view, the line motion and RT measures revealed only speeded processing at previously stimulated spatial locations. Experiment 3 required a simple detection response and used the same stimulus and timing parameters as those in Experiments 1 and 2. IOR was present, replicating the recent finding that judgments based on perceptual qualities of the stimulus do not demonstrate a RT delay, whereas simple detection tasks do show RT inhibition at previously stimulated locations. These findings are discussed in relation to a number of hypotheses about the origin of the RT delay.

Steam sterilization trends in the U.S.A.

Steam sterilization practices, standards, and products in the United States are changing as the U.S. health care system continues to undergo dramatic restructuring. The causes of this restructuring are hospital consolidations, implementation of diagnostic-related-group reimbursement, cost-containment programs, and increasing acceptance of disposable packs.

Legal incompetents' need for guardians in Florida.

This study assesses the alleged need for guardians in Florida. A survey of the state's 74 public receiving facilities, community mental health centers, and clinics; 30 private receiving facilities; 11 Aging and Adult district offices; Developmental Services institutional and residential placements; and six state mental hospitals revealed that 11,147 persons in Florida reportedly need a legal guardian. The limitations, implications, and possible policy responses to this alleged need are discussed.

Method for quantitative estimation of thermal thresholds in patients.

A quantitative method for the examination of thermal sensibility was applied in 26 normal subjects and in patients with various neurological disorders. The stimulation technique resembled Békésy audiometry: the patient reversed the direction of the temperature change of a thermode whenever warm, cold, or thermal pain thresholds were reached. The resulting temperature curve enables a quantitative description of the subject's thermal sensibility and of the degree of impairment displayed by neurological patients.

Purification and characterization of a Streptomyces albus endo-N-acetylmuramidase lytic for group A and other beta haemolytic streptococci.

The purification and characterization of the streptolytic exo-enzyme from the Maxted-McCarty strain of Streptomyces albus is described. This enzyme was shown to be an endo-N-acetylmuramidase with a molecular weight of 10 to 12,000 and optimal activity at pH 8 and 45 degrees C. The enzyme is lytic for streptococci of various groups, Micrococcus lysodeikticus, Staphylococcus aureus, as well as Escherichia coli. It closely resembles the F1 endo-N-acetylmuramidase described by Ghuysen et al. (1966) except for small differences in the products of lysis of streptococcal cell walls and the resistance of Escherichia coli to lysis by the F1 enzyme. Lysates of group A and A variant streptococcal cell walls prepared with purified Streptomyces albus muramidase contained serologically active M protein and C carbohydrate-peptidoglycan complexes. The chemical and immunological characteristics of these enzymmatic products of streptococcal cell walls are reported and their utility as immunologic reagents is described.