Total Presentation Time Research Articles

Unreimbursed Costs of Multidisciplinary Conferences to a Radiology Department: A Prospective Analysis at an Academic Medical Center

PurposeMultidisciplinary conferences (MDCs) are important for clinical care but are unreimbursed and can be time-consuming for radiologists to prepare for and present. The purpose of this single-center, prospective, survey-based study is to measure the per-conference time and total time radiologists devote to MDCs at a single academic medical center. Secondary objectives are to determine the source of radiologist preparation time, and calculate the per conference and overall radiology departmental costs of MDC participation. MethodsA prospective survey was performed to capture all radiology preparation and presentation time for MDCs in a 3-month period, which was then annualized. Total cost was calculated on the basis of Association of Administrators in Academic Radiology survey data for nonchair academic radiologist compensation plus a 30% fringe-benefit rate. ResultsThe survey response rate was 86.9%. A total of 3,358 hours were devoted annually to MDCs, which represents time equivalent to 1.9 full-time equivalents or $1,155,152 in unreimbursed radiology departmental costs. Per-MDC total preparation and presentation time was 2.7 hours, at an annual cost of $46,440 for each weekly MDC. Radiologists used a combination of personal time (49.7%), academic time (42%), and/or clinical time (35.4%) to prepare for MDCs. Radiologists devoted a mean of 47.9 hours (1.2 weeks) of time per annum to MDCs. ConclusionsRadiologist time devoted to MDCs at the survey institution was substantial, and preparation time was drawn disproportionately from personal and academic time, which may have negative implications for burnout, recruitment and retention, and academic productivity unless it is effectively mitigated.

Decision-making from temporally accumulated conflicting evidence: The more the merrier.

How do humans evaluate temporally accumulated discrete pieces of evidence and arrive at a decision despite the presence of conflicting evidence? In the present study, we showed human participants a sequential presentation of objects drawn from two novel object categories and asked them to decide whether a given presentation contained more objects from one or the other category. We found that both a more disparate ratio and greater numerosity of objects improved both reaction time (RT) and accuracy. The effect of numerosity was separate from ratio, where with a fixed object ratio, sequences with more total objects had lower RT and lower error rates than those with fewer total objects. We replicated these results across three experiments. Additionally, even with the total presentation duration equated and with the motor response assignment varied from trial to trial, an effect of numerosity was still found in RT. The same RT benefit was also present when objects were shown simultaneously, rather than sequentially. Together, these results showed that, for comparative numerosity judgment involving sequential displays, there was a benefit of numerosity, such that showing more objects independent of the object ratio and the total presentation time led to faster decision performance.

Distinct temporal mechanisms modulate numerosity perception.

Our ability to process numerical and temporal information is an evolutionary skill thought to originate from a common magnitude system. In line with a common magnitude system, we have previously shown that adaptation to duration alters numerosity perception. Here, we investigate two hypotheses on how duration influences numerosity perception. A channel-based hypothesis predicts that numerosity perception is influenced by adaptation of onset/offset duration channels which also encode numerosity or wire together with numerosity channels (duration/numerosity channels). Hence, the onset/offset duration of the adapter is driving the effect regardless of the total duration of adaptation. A strength-of-adaptation hypothesis predicts that the effect of duration on numerosity perception is driven by the adaptation of numerosity channels only, with the total duration of adaptation driving the effect regardless of the onset/offset duration of the adapter. We performed two experiments where we manipulated the onset/offset duration of the adapter, the adapter's total presentation time, and the total duration of the adaptation trial. The first experiment tested the effect of adaptation to duration on numerosity discrimination, whereas the second experiment tested the effect of adaptation to numerosity and duration on numerosity discrimination. We found that the effect of adaptation to duration on numerosity perception is primarily driven by adapting duration/numerosity channels, supporting the channel-based hypothesis. In contrast, the effect of adaptation to numerosity on numerosity perception appears to be driven by the total duration of the adaptation trial, supporting the strength-of-adaptation hypothesis. Thus, we show that adaptation of at least two temporal mechanisms influences numerosity perception.

P-258 - Canadian child and adolescent mental health services - “brampton civic hospital model” (video presentation)

Brampton Civic is situated in a vibrant multicultural community in the outskirts of Toronto. Since inception in 1987, the program has grown to encompass a central intake, Out- patient services, intensive unit, inpatient services, and a day hospital, incorporating a preexisting out- patient community psychiatric clinic. Within this continuum of services, staff members use a multidisciplinary team approach to treat children and adolescents up to 17 years of age. For example, central intake provides the screening service for all referrals to the program. The out- patient service provides an initial psychiatric consultation and some limited follow-up. The intensive unit's role is to stabilize the acutely ill in a secure and supportive setting. Assessment initiation and determination of the next steps in management of the illness is also done by the unit. Once stabilized, the patient may move to the “step-down” inpatient unit, or the day hospital depending on mental status and individual needs. The patient receives multidisciplinary assessment of symptoms and stabilization of mental status through various therapeutic modalities. A central focus in treatment is on improvement of normal functioning within the context of family, community, and school. The program also endorses ongoing professional and educational development, essential to ensure the delivery of effective and efficient health care. This is a unique video presentation,includes the physical structure of the Child psychiatry unit and lively interaction by 20+ clinicians as a multidisciplinary team, describing their roles and contributions to the program. Total presentation time will be approximately 50 minutes.

Library Camps and Unconferences

Library Camps and Unconferences

The ability to execute saccades on the basis of efference copy: impairments in double-step saccade performance in children with developmental co-ordination disorder.

The double-step saccade task (DSST) was used to test the hypothesis that children with developmental co-ordination disorder (DCD) who experience deficits in motor imagery have difficulty processing the visual spatial consequences of intended movements using efference copy signals. In order to ensure that the second saccade in the DSST was executed in the absence of visual cues and had to be programmed on the basis of extra-retinal information (efference copy), we analysed only those double-step ensembles where latency plus duration of first saccades was greater than 240 ms (total presentation time of the targets). No significant differences between DCD and control children were evident on measures of latency of first saccades, intersaccadic interval and first saccade error. As predicted, children with DCD who have impaired motor imagery demonstrated specific deficits on the DSST where efference copy had been used to program the saccade sequence. More specifically, these children were less accurate in terms of final eye position on second saccades. Our results raise the possibility that abnormalities in the processing of efference copy signals could underlie motor clumsiness in the majority of children with DCD. Furthermore, the origin of this deficit in efference copy probably exists at the level of the parietal lobe.

Improvement of picture recall by repetition in patients with dementia of Alzheimer type.

The evidence for positive effects of repetition on recall performance in patients with dementia of Alzheimer type is equivocal. This may be due to the difference repetition conditions used. The aim of this study was therefore to evaluate the effects of different repetition modes on the improvement of recall performance in demented subjects. Twenty-four patients with Alzheimer type dementia and 24 control subjects with remitted depression were included in the study. Pictures were presented repeatedly using different presentation modes at a constant total presentation time. Free recall was tested repeatedly after different periods of delay (0-8 hours). Immediate and delayed list repetition significantly improved recall performance in both groups. Within-list repetition did not improve total recall in demented subjects. The repeated measurement design sensitively detected minor changes in recall performance. These were not observed using other measures of recall and recognition (hits, false alarms, indices of signal discrimination).

On the time-course of inhibition in the stereoscopic perception of rows of dots

Perception of depth difference between two dots is more difficult if additional dots intervene between them. By varying the onset asynchrony (SOA) between the endpoints and one or several intervening dots, we measured the time-course of the process that elevates stereoscopic thresholds. It turned out that adding the intervening dots under these conditions decreased performance to, and often below, the level that was achieved with a total presentation time corresponding to the SOA for intervening dots presented both binocularly and monocularly. This is an indication for an active inhibitory process.

Aging and the total presentation time hypothesis.

Aging and the total presentation time hypothesis.

Aging and the total presentation time hypothesis.

Aging and the total presentation time hypothesis.

Sex Differences in Learning Connected Discourse as a Function of Exposure and Interitem Intervals

Learning of connected discourse was contrasted for males and females for differing exposure and interitem intervals. With total presentation time constant, it was more difficult for males to learn the material when the interitem interval was greater than the exposure interval rather than the reverse. Females appeared to learn equally well under both conditions.

The influence of repetition vs. no repetition given equal presentation time on the learning of connected discourse

Subjects were required to learn a 25 words-in-length passage of connected discourse. The general design was a single 2 x 5 factorial. The dichotomous dimension was repetition or no repetition of the learning material. The other dimension represented total presentation time and ranged from 20 to 60 seconds. There was a lack of significance of total presentation time on total learning time but a consistent and strong superiority of the repetition condition on the no repetition condition.

The effects of spatial, temporal, and control variables on the free-recall serial position curve of retardates and equal-MA normals

In Experiment I seven pictures were sequentially illuminated at a 3-see rate through seven translucent windows. A different window provided the starting point for each of seven tests. Retarded and normal Ss of equal MA produced equivalent free recall and reliable recency effects. Although groups did not differ significantly at any portion of the curve, only the normals produced a significant primacy effect. The spatial end anchors produced no significant primacy or recency effects. In Experiment II total presentation time remained the same but the pictures were presented at a 1-sec rate. Variations in elapsed time and number of Presentations produced a negative primacy effect, a result attributed to the prevention of selective rehearsal and the resultant interaction of trace decay and order of recall. Superior recall by the normals, particularly in the recency portion of the curve, was attributed to group differences in order of recall strategies.

Total presentation time and trials to criterion in connected discourse learning

Seven sets of data are presented which summarize the relationship between trials to criterion and total presentation time for a 25-word-long passage of connected discourse. The resultant relationship shows a sharp negative deceleration with trials to criterion becoming quickly asymptotic between two and two and one-half trials. Implications of this relationship to the total-time hypothesis for connected discourse learning are briefly presented.

Total presentation time and total learning time in connected discourse learning.

Total presentation time and total learning time in connected discourse learning.

Presentation Time and Method of Reading in the Learning of Connected Discourse

Summary This study investigated the joint influence of total presentation time (10, 20, or 30 seconds) and method of reading (paced, normal linguistic breaks, or atypical linguistic breaks) on the learning of a 25 words-in-length passage of connected discourse. The material was presented orally and the recall was written. The finding of major importance was the significant influence of method of reading on total learning time.

Test of the total-time hypothesis in free-recall learning.

A test of the total-time hypothesis in free-recall learning is reported. The hypothesis asserts that the amount recalled is determined by the total presentation time (TPT), regardless of list length (LL) and rate of presentation (RP). The purpose of the experiment was to verify the validity of this principle and to examine some potential limitations on its operation. With TPT held constant at 60 sec., there were three conditions of presentation: (a) LL 20 and 3-sec. RP; (b) LL 30 and 2-sec. RP; (c) LL 60 and 1-sec. RP. A first test of recall was given either immediately after a single presentation of the list or after an interval of 20 min. The first test was followed by two additional study-test cycles. In accord with the hypothesis, the amount recalled on the first test was invariant across conditions after both retention intervals, i.e., the operation of the principle was found to be independent of delay. After the first test, gains as a function of practice were related directly to LL. The longer the list the more new items were added on each test, although intertrial retention was essentially invariant under the different treatments. The divergence of the learning curves is attributed to the covariation of LL and the amount of semantic and associative overlap among individual items. This study is concerned with the totaltime hypothesis in free-recall learning. The hypothesis asserts that the amount recalled is determined by the total presentation time (TPT), independently of the length of the list (LL) and the rate of presentation (RP) for individual items. As long as the product LL X RP is held constant, the number of items recalled is expected to be the same. This expectation was fully supported in an experiment by Murdock (1960) in which LL and RP were varied concomitantly while TPT remained unchanged. There were four combinations of LL and RP which yielded closely similar recall scores: 20-3 (a 20-word list presented at a rate of 3 sec. per item), 30-2, 40-1.5, and 60-1. In addition to the principle of recall invariance illustrated by these findings, Murdock (1960) advanced the hypothesis that the amount of recall is a linear function of TPT. We shall not consider further the latter hypothesis, which has been called into question by the results of subsequent investigations (Roberts, 1972; Waugh, 1967). Rather attention will be 1 This research was supported by Grant MH-12006

Total time and presentation time in paired-associate learning.

Total time and presentation time in paired-associate learning.

Temporal discrimination as a function of total presentation time

Two triangles (Δ and ∇) were presented successively at the same spatial locus for binocular viewing. Manipulation of stimulus duration and interstimulus interval revealed that accuracy in discriminating order is dependent upon total time (S1 + ISI + S2) and that the discrimination threshold (75% correct) is approximately 100 msec.

The Effect of Various Presentation Patterns on the Comprehension of Speeded Speech

During the past ten years, a body of research has been accumulated related to the comprehension of speeded speech. The results generally indicate that it is possible for listeners to comprehend effectively continuous meaningful discourse at rates far above those normally encountered in everyday listening. Fairbanks, Guttman, and Miron (1957a) found that auditory presentations made at the rate of 282 words per minute (wpm) produced the optimum efficiency of comprehension where efficiency was determined by dividing the comprehension test score by the time required for presentation. The latter research workers then went on to investigate the effects of making two consecutive redundant presentations with the hypothesis that this should produce higher mean comprehension test scores than a single presentation at half the speed (Fairbanks, Guttman, and Miron 1957b). The results supported this hypothesis. Various combinations of redundant speeded presentations were first used in an investigation by Reynolds (1966). Reynolds used six combinations of repeated auditory presentations. An interesting result of the experiment was that when four progressively slower presentations were made (350 to 200 wpm), the mean comprehension test scores were reliably higher than when the same number of presentations, occupying the same total presentation time, were made in either an ascending (200 to 350 wpm) order or when the material was presented at 263 wpm on each of four trials (which also occupied the same amount of time).