Biomedical subjects

L P Shiu

Publications and source records attributed to L P Shiu.

9 recordsLinked to original sources

PubMed1999

Do images involuntarily trigger search? A test of Pillsbury's hypothesis.

Pillsbury (1908) suggested that deciding to search for something in a scene consists of nothing more than forming a visual image of the target. If so, imaging should trigger search even when it would be more advantageous not to search. Subjects were cued to form an image of a specified object (e.g., tiger) and to press a key when they had done so. This initiated the presentation of a sequence of pictures, with a single target digit interspersed; the subject's task was to report this digit. The sequence contained a picture of the same type of object that the subject had just imaged (e.g., a tiger), either before or after the target digit. If this picture was detected involuntarily, an attentional blink should have impaired digit detection when the picture preceded the digit. This was confirmed in two experiments, even when instructions specifically encouraged subjects to discard the image and to avoid searching for it. The results support Pillsbury's hypothesis.

Attention↗

PubMed1999

Stimulus-response compatibility effects in go-no-go tasks: a dimensional overlap account.

According to the automatic response activation hypothesis of the dimensional overlap (DO) model (Kornblum, Stevens, Whipple, & Requin, 1999), stimulus-response compatibility effects are expected to occur in go-no-go tasks. This prediction is confirmed in two experiments in which subjects moved a hand to one side of the field on presentation of a go stimulus. Although the direction of movement was known in advance and the spatial attribute of the go stimuli was irrelevant to the go-no-go decision, the subjects' response time was shorter when the spatial attribute to the go stimulus corresponded to that of the response than when it did not. These effects are shown to depend on the similarity of the go and the no-go stimuli, as well as on whether the spatial attribute of the go stimuli was its actual location or its meaning. We discuss these results in terms of the temporal dynamics of automatic and controlled response processes, as hypothesized in the DO model.

Adult↗

PubMed1995

Spatial attention and vernier acuity.

This study examined whether or not vernier acuity would be improved if the location of a briefly presented vernier stimulus was pre-cued. The vernier target appeared alone, or together with straight lines or ellipses. Effects of spatial pre-cuing were found only when straight line distractors were present. It is suggested that since the straight lines are confusable with the vernier targets, they introduce statistical noise in decision. Precuing the most probable location that contains a target may help by allowing this noise to be excluded.

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PubMed1993

Negative social events, stress, and health in Hong Kong.

STUDY OBJECTIVE: To investigate the association, if any, between negative social events and physical illness. DESIGN: Comparison of major social events and indices of disease. SETTING-Hong Kong, 1962 to 1985. SUBJECTS: Patients treated in hospital for attempted suicide, coronary heart disease, and diabetes mellitus. MEASUREMENTS AND MAIN RESULTS: Major events were selected from the annual Hong Kong Year Book, and grouped in one of 18 categories by a panel of 10 assessors. Weights were assigned to each category according the likely stress produced. Individual events were then scored and multiplied by the category weights to produce an overall stress score from which a total stress score for each year was derived. Annual stress scores were then compared with hospital attendance rates for the three medical conditions. CONCLUSIONS: The study has shown that: (1) the stress induced in the community by major negative social events in Hong Kong had been increasing; and (2) this stress is associated with attempted suicide but not with diabetes mellitus or coronary heart disease.

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PubMed1992

Life events and daily stress in duodenal ulcer disease. A prospective study of patients with active disease and in remission.

Life events and daily stress were assessed in patients with duodenal ulcer, active or in remission, and in matched disease and normal controls. The mean positive life event scores were significantly lower in duodenal ulcer patients than in disease and healthy controls, and lower in patients with active ulcer than in those in remission. The positive scores and total life change scores decreased significantly after 6 months in the control groups and showed no significant variation in the duodenal ulcer group after 6 months. We conclude that the perception of life events, especially positive ones, is associated with duodenal ulcer.

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PubMed1992

Improvement in line orientation discrimination is retinally local but dependent on cognitive set.

The ability of human observers to discriminate the orientation of a pair of straight lines differing by 3 degrees improved with practice. The improvement did not transfer across hemifield or across quadrants within the same hemifield. The practice effect occurred whether or not observers were given feedback. However, orientation discrimination did not improve when observers attended to brightness rather than orientation of the lines. This suggests that cognitive set affects tuning in retinally local orientation channels (perhaps by guiding some form of unsupervised learning mechanism) and that retinotopic feature extraction may not be wholly preattentive.

Adult↗

PubMed1991

The perception of life events and daily stress in nonulcer dyspepsia.

Previous studies on the association of nonulcer dyspepsia with major life events were performed without emphasis on the perception of these events, and have yielded conflicting results. The present study examined the perception of life events and, in addition, the role of daily "hassles" (stressful events) in patients with nonulcer dyspepsia. Thirty-three dyspeptic patients as defined by normal endoscopy and ultrasonogram and 33 controls of comparable sex, age, and social class were recruited for study. Both groups were asked to select from 56 major life events those they had experienced and to give a rating on how they perceived them. They were further asked to select similarly from 117 items of daily stress and to rate the severity of each item. The results demonstrated that the number of positive and negative events and the positive score were similar in both dyspeptic patients and controls, but dyspeptic patients had a higher perceived magnitude of negative events and a higher score of total life change as given by the summation of magnitude of positive and negative events (both p less than 0.05). The "hassles" scores were not significantly different between dyspeptic patients and controls. Analysis of individual life events revealed that dyspeptic patients had significantly (p less than 0.05) higher scores than controls in items of minor law violations, major change in closeness of family members, and major personal illness or injury. We conclude that patients with nonulcer dyspepsia have higher negative perception of major life events, which indicates that psychological factors may play a role in the pathogenesis of nonulcer dyspepsia.

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PubMed1989

Cerebral lateralization of Chinese-English bilingual functions.

There is evidence that auditory reception of the second language of bilinguals is less lateralized in the left hemisphere, when the two languages involved are more dissimilar, such as Chinese and English. The present study shows, with a test of simultaneous finger tapping and backward counting as well as a test of tachistoscopic bilateral presentation, that this differential lateralization does not apply to non-auditory functions, and both Chinese and English showed a left hemisphere advantage. Bilateral presentation of bilingual words produced greatest interference, when compared with bilateral presentation of unilingual words, or bilateral presentation of words and numbers.

Adult↗

PubMedDate not supplied

Society stress and peptic ulcer perforation.

To examine the relationship between society stress and peptic ulcer perforation, time-trend analysis was performed on the annual incidence of perforated peptic ulcer per 100,000 population in Hong Kong during the years 1962-85, when Hong Kong, as a developing city, went through significant socio-economic and political changes, and the trend was correlated with specially designed and validated society stress scores estimated annually during the same period. The society stress scores were derived independently by two expert panels blinded to the purpose of the study, one selecting and categorizing negative news events for Hong Kong during this period, and the other weighing the categories and scoring the impact of the news on Hong Kong. The incidence of perforation increased significantly during the years and manifested three distinct peaks, which coincided with the worst economic recession in Hong Kong, the influx of mainlander Chinese and Vietnamese boat people, and the Sino-British negotiation on the sovereignty of Hong Kong after 1997. Both linear and autoregression analysis, the latter taking into consideration point fluctuations in rates, showed that perforation rates correlated significantly with the society stress scores (r = 0.57, P < 0.002). The peak effects and the significant correlations indicate that an association exists between society stress and peptic ulcer perforation, and suggest that chronic society stress plays an important role in the aetiology of this condition, although the relatively low r value also suggests the presence of other aetiological factors.

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