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Biomedical subjects

A Osman

Publications and source records attributed to A Osman.

At least 19 recordsLinked to original sources
PubMed1992

On the transmission of partial information: inferences from movement-related brain potentials.

Results are reported from a new paradigm that uses movement-related brain potentials to detect response preparation based on partial information. The paradigm uses a hybrid choice-reaction go/nogo procedure in which decisions about response hand and whether to respond are based on separate stimulus attributes. A lateral asymmetry in the movement-related brain potential was found on nogo trials without overt movement. The direction of this asymmetry depended primarily on the signaled response hand rather than on properties of the stimulus. When the asymmetry first appeared was influenced by the time required to select the signaled hand, and when it began to differ on go and nogo trials was influenced by the time to decide whether to respond. These findings indicate that both stimulus attributes were processed in parallel and that the asymmetry reflected preparation of the response hand that began before the go/nogo decision was completed.

Decision Making↗
PubMed1992

Factor structure and reliability of the Reasons for Living Inventory.

This study examined the factor structure and internal consistency reliability of the Reasons for Living Inventory for 275 college students. Principal components factor analysis with varimax rotation extracted five factors, based on the scree test. The derived factors were identical with the inventory's subscales, except for the Fear of Suicide subscale and Social Disapproval subscale items loading on the same factor. Significant gender differences were obtained on the Responsibility to Family, the Fear of Suicide, and the Moral Objections subscales. The pattern of subscale correlations was similar for the subsamples. The coefficients alpha for the subscales ranged from moderate to high.

Adult↗
PubMed1992

Reliability and validity of the Cognitive Slippage Scale in two populations.

Analyses of responses from a clinical sample of 120 patients (primarily schizophrenics) and from 158 college students to the Cognitive Slippage Scale, a scale designed by Miers and Raulin to identify speech deficits and confused thinking in schizophrenic and schizotypal personality disorders showed high internal reliability; Cronbach's coefficients alpha were .89 and .86 in the clinical and college student samples, respectively. The mean scale scores significantly differentiated the two samples. Also, change scores over 4 wk. showed adequate stability for both samples. Item analysis indicated Items 11, 20, 21, and 28 may not reliably discriminate between schizophrenic and college student samples. Over-all, these preliminary results are consistent with the reliability and validity of the scale.

Adult↗
PubMed1992

Psychometric properties of the Social Interaction Self-Statement Test in a college sample.

The psychometric properties of the Social Interaction Self-statement Test were investigated with a sample of 321 college students. Factor analysis of the 30 items gave two factors, similar to the positive and negative self-statement subscales. The internal consistency coefficients of the factor scales were high and adequate. Correlations between the subscales and independent measures of social anxiety and psychological distress from the Symptom Checklist-90--Revised were examined. Data provided opportunity for evaluating the construct validity and psychometric adequacy of the test.

Adult↗
PubMed1991

The Reasons for Living Inventory: psychometric properties.

The test-retest reliability, internal consistency reliability, normative, and item analysis data of the Reasons for Living Inventory were investigated in a sample of 116 college students. The inventory has six subscales, each of which assesses a category of adaptive beliefs and expectations considered reasons for not committing suicide. The inventory was administered twice, with a 3-week interval between testings. Test-retest coefficients for the men, women, and total sample were moderate to high. The alpha coefficients and item-total correlations for the subscales and the total inventory provided strong support for internal consistency. 26 items were consistently endorsed by 30% or more of our total sample as "extremely important," while only four were suggested as "not at all important" reasons for not committing suicide.

Adolescent↗
PubMed1990

Does motor programming necessitate response execution?

The complexity of a movement is known to affect the time it takes to initiate the movement. This effect is thought to reflect changes in the duration of processes that operate on a motor program. This question addressed here is whether programming a movement compels the start of its overt execution. If it does, then the programming processes may be said to occur after the "point of no return." We report results from an empirical procedure and a theoretical analysis designed to study processes before and after this point separately. According to our results, changes in the complexity of a movement affect only the prior set of processes. From this we argue that motor programming does not necessitate response execution and that the point of no return occurs very late in the information-processing system.

Adult↗
PubMed1990

Dimensional overlap: cognitive basis for stimulus-response compatibility--a model and taxonomy.

The classic problem of stimulus-response (S-R) compatibility (SRC) is addressed. A cognitive model is proposed that views the stimulus and response sets in S-R ensembles as categories with dimensions that may or may not overlap. If they do overlap, the task may be compatible or incompatible, depending on the assigned S-R mapping. If they do not overlap, the task is noncompatible regardless of the assigned mapping. The overlapping dimensions may be relevant or not. The model provides a systematic account of SRC effects, a taxonomy of simple performance tasks that were hitherto thought to be unrelated, and suggestive parallels between these tasks and the experimental paradigms that have traditionally been used to study attentional, controlled, and automatic processes.

Arousal↗
PubMed1990

Psychometric properties of the Social Fear Scale.

The present study attempted to replicate the internal consistency of the Social Fear Scale as well as test-retest, normative and item analysis because these estimates have not been reported. Cronbach alpha s of 0.87 for 38 men and 0.88 for 74 women in college were similar to those reported in 1984 by Raulin and Wee. Test-retest reliability coefficients for the total sample and for each subsample (normative data) indicated strong support for the stability of responses over a 4-wk. period. An item analysis suggested two items may not be useful for assessing social fear. Questions for research are discussed.

Adolescent↗
PubMed1989

Mental slowing in elderly persons: a cognitive psychophysiological analysis.

In recent attempts to formulate an integrative model of mental slowing in elderly persons, regression analyses have been done in which reaction-time data from a large number of studies spanning a broad range of speeded decision-making tasks were combined. The results of these meta-analyses were then used to support the conclusion that there is a generalized, proportional decline in mental processing speed among elderly adults that affects all elements of mentation equally. We present a series of similar regression analyses in which both reaction time and the latency of the P300 component of the event-related brain potential are included. The results of these analyses indicate that there are elements of mental processing that may be slowed additively, not proportionately, in older persons. Furthermore, the results raise some questions about the logic underlying the interpretation of the meta-regression analysis.

Adult↗
PubMed1989

A study of locomotor disabilities in a Malay community in Kuala Selangor.

A study was conducted to determine the prevalence of locomotor disability in a Malay Community in Tanjung Karang, Kuala Selangor in 1984. The causes of these disabilities, the mobility and occupational handicaps they caused and the types of treatment received were determined. Fifty percent of the households in this area were selected by stratified random sampling and all persons above seven years of age were included in the sample. The prevalence of locomotor disability was 3.9%. The prevalence among males was 5.2% and among females 2.6%. The prevalence increased with age, being as low as 0.6% in the 7-14 year age group and as high as 20.5% in the above 55 year age group. The disabilities resulted mainly from trauma (49%) and musculoskeletal and neurological problems (46.9%). Ninety percent (44 cases) had difficulty only in performance of daily activity and 20 cases (40.8%) had no mobility handicap whatsoever. Forty two (85.7%) of the 49 cases had received treatment.

Adolescent↗
PubMed1987

Joint mobility and mitral valve prolapse in an Arab population.

The association of joint laxity and mitral valve prolapse (MVP) has been disputed. In this study of an Arab population, the joint mobility scores of 29 subjects with MVP, 10 of whom were asymptomatic, were compared to 60 normal controls. It was found that the joint mobility score was significantly higher in both the asymptomatic and the symptomatic subjects with MVP when compared to the controls. This suggests that both mitral valve prolapse and joint laxity may be due to the same abnormality of connective tissue structure.

Adult↗
PubMed1986

The point of no return in choice reaction time: controlled and ballistic stages of response preparation.

A countermanding procedure and race model are used to assess separately the effects of experimental factors before and after the "point of no return" in response preparation. The results reveal details about processes that so closely precede the initiation of movement that they cannot be inhibited. These processes appear to be affected by the repetition of stimulus-response pairs, but not by the physical or semantic properties of the stimuli. A model of response preparation is supported in which response inhibition depends upon the outcome of a race between independent excitatory and inhibitory processes, and reaction time is the sum of the durations of at least two stages, separated by the point of no return.

Choice Behavior↗
PubMed1978

[Parameters of the cellular cyle during odontogenesis in mice].

Autoradiographic methods were used to analyze cell kinetics of mouse tooth germs during days 11, 14 and 16 of gestation. Cell cycle determination estimated from the labeled metaphases curves showed a lengthening of the cell cycle time during development, resulting from lengthening of G1 and S phases. These changes were also function of the histological localization of the analyzed cells.

Animals↗