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Biomedical subjects

M M Sebrechts

Publications and source records attributed to M M Sebrechts.

6 recordsLinked to original sources
PubMed1999

Heuristic evaluation of a web-based interface for internet telemedicine.

A low-cost usability engineering methodology (heuristic evaluation combined with small-scale expert assessment) is examined in the context of the design and development of a Web-based telemedicine system. Six experts - three human-computer interaction (HCI) experts and three medical-content experts - examined the Spacebridge to Russia Web site for usability. The HCI experts identified 52 interface problems using a set of ten usability criteria or heuristics; these problems ranged in severity from cosmetic to a major failure. The content experts completed a series of six simple tasks while describing their actions. The usage difficulties were related to the HCI problems identified and were primarily characterized by a mismatch of the designer model and the content expert model. This heuristic/usage methodology can provide an incremental benefit in a variety of other design activities. It is suggested herein that the combined heuristic/usage methodology should be included as a standard design component of dynamic telemedicine systems.

Ergonomics↗
PubMed1997

Processing strategies and secondary memory in very rapid forgetting.

When a memory test is unexpected, recall performance is quite poor at retention intervals as short as 2-4 seconds. Orienting tasks that change encoding conditions are known to affect forgetting in such "very rapid forgetting" paradigms where people are misled to believe that recall will not be required. We evaluated the hypothesis that differences in forgetting among orienting tasks are attributable to contributions of secondary memory during encoding in two experiments. In Experiment 1, short-term recall performance was inversely related to task demands during encoding, although long-term memory performance was not. Task demands were assessed by making the duration of stimulus presentation dependent on the time required to perform three different orienting tasks. In Experiment 2, we compared performance of that variable-length stimulus presentation to the fixed-length presentation used in most prior research. The results suggested that additional encoding or rehearsal time does not have an appreciable impact on short-term performance. Thus, differences in forgetting appeared to be a function of the contribution of secondary memory rather than a function of the time available to engage in primary memory rehearsal strategies.

Analysis of Variance↗
PubMed1990

Growth hormone and prolactin response to methylphenidate in children with attention deficit disorder.

Utilizing a double-blind, drug-placebo design, we examined growth hormone (GH) and prolactin (Pro) response to oral administration of methylphenidate (MPH) in 14 boys (ages 7.0-12.4 years) with Attention Deficit Disorder (ADD). Four conditions representing three different MPH doses (0.3 mg/kg O.D., 0.3 mg/kg B.I.D., 0.6 mg/kg O.D.) and Placebo were compared in each subject, each condition lasting for a period of 3 weeks. GH and Pro response were measured both as maximum peak GH (DGH) or nadir of Pro (DPro) as well as area under the curve for the first four hours after MPH administration (AUCGH, AUCPro). Behavioral measures included parent ratings on the Yale Children's Inventory and teacher ratings on the Yale and Conners Behavior Rating Scales and Kagan's Matching Familiar Figures Test (MFFT). Prolactin response as measured by AUCPro was significantly increased after MPH compared to placebo (t = 2.04, p less than 0.05, placebo vs all doses MPH). This difference observed for AUCPro between placebo and MPH was evident as well when we considered the number of times AUCPro declined after MPH as compared to placebo (p = .018, Fisher's exact test). Within-subjects analysis of covariance demonstrated significant correlations between the improvement in reaction time on the MFFT and 1) GH response (AUCGH, r = .58, p less than .001) and 2) prolactin response (AUCPro, r = .40, p less than .05) and between improvement in attention as measured on the Yale BRS and GH response (AUCGH, r = .57, p less than .05). Our findings suggest that measures other than GH and prolactin may be more desirable measures of brain catecholaminergic functioning.

Attention Deficit Disorder with Hyperactivity↗
PubMed1989

Secondary memory and very rapid forgetting.

Studies of recall in the absence of expectancy (e.g., Muter, 1980) have suggested that forgetting from primary memory is much more rapid than previously assumed. Two experiments examined the role of secondary memory, as reflected by encoding strategies, in determining this rate of forgetting. Experiment 1 demonstrated that the type of encoding specified by orienting tasks can influence recall in a traditional Brown-Peterson task. Experiment 2 demonstrated a similar pattern of effects of orienting task in the Muter task when recall was not expected, despite much more rapid forgetting. The type of encoding engaged by the orienting tasks did not account for Muter's results. Expectancy and orienting task appear to have separable influences on resource allocation during encoding. The presence of secondary memory influences at even the shortest retention interval indicates that forgetting from primary memory may be even more rapid than has been proposed.

Adolescent↗
PubMed1986

Components of attention, methylphenidate dosage, and blood levels in children with attention deficit disorder.

In this study we analyzed some of the cognitive components that may constitute attention deficit disorder. It consisted of a double-blind, drug-placebo study of 12 children being treated with three doses of methylphenidate and placebo. Results of an attentional test battery, teacher and parent ratings, and blood levels of methylphenidate are reported. In general, performance was best with 0.6 mg/kg of methylphenidate (the highest dose tested) and worst with placebo. It is argued that no single test provides a complete assessment of attentional deficits and that methylphenidate can improve performance by affecting the allocation of cognitive resources to a task.

Adolescent↗