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At least 19 recordsLinked to original sources
PubMed1975

Waiting for a crowd: the behavioral and perceptual effects of anticipated crowding.

An experiment was conducted in which subjects were convinced that crowding was imminent. It was hypothesized that the arousal of expectations of crowding would cause subjects to behave in ways suggesting that they were preparing for the experience of crowding by taking steps to reduce the impact of crowding before its onset. Similarly, it was predicted that anticipation of crowding would influence subject perceptions of the experimental room, interpersonal affect, and general levels of discomfort. Data collected indicated that these predictions were accurate; subjects anticipating crowding chose more socially isolated seat positions, avoided contact with others, experienced crowding and discomfort, and rated others in the setting as well as the room in ways generally consistent with definitions of crowding.

Adolescent↗
PubMed1995

Depth discrimination of a crowded line is better when it is more luminant than the lines crowding it.

Observers usually cannot discriminate the relative depth of a crowded feature with respect to crowding features about 2 arc min distant if all the features have the same luminance. However, stereo thresholds significantly less than 20 arc sec are obtained when the crowded feature is about twice as luminant as the features crowding it. The thresholds depend only upon the ratio of the luminance of the target feature to the luminance of the crowding features and are independent of the absolute luminance of the features. With further increase in the relative luminance of the target feature, the performance eventually deteriorates and this deterioration is not due to difficulty in seeing the features which were individually clearly visible for all the luminances tested. The closest spacing of local crowded features that still allows good stereo discrimination is about the same as the spatial resolution attainable for many luminance-based non-stereo tasks.

Depth Perception↗
PubMed1994

[Effects of crowding on immune functions in mice].

The effects of several types of crowding on immune functions were studied in mice. This study consisted of two experiments. Experiment one: Male BALB/c mice were initially housed in groups of four mice per cage. After fourteen days of acclimation, the mice were randomly divided into three groups, Control (four mice per cage, control group), Crowd-I (four mice per small space) and Crowd-II (sixteen mice per cage). These conditions were maintained for seven days. The results of experiment one were as follows: (1) The percentage of lymphocytes in the blood of Crowd-II was significantly lower than that of Control (p < 0.05). (2) The percentage of neutrophils and the absolute number of neutrophils in blood of Crowd-II were significantly higher than in Control (p < 0.05). (3) Superoxide production activity (NBT reduction activity) of blood neutrophils in Crowd-II tended to be depressed, and phagocytic activity of neutrophils was significantly depressed in Crowd-II as compared with Control (p < 0.01). These results suggest that the complexity of interrelationships among mice caused by an increase in the number of animals per cage is a very important stress factor. Experiment two: Male BALB/c mice were initially housed in groups of five mice per cage. After fourteen days of acclimation, the mice were divided into three groups, Control (five mice per cage, control group), Crowd-(1) (five mice per cmall space) and Crowd-(2) (twenty mice per cage). In Control and Crowd-(1), the same mice were used as in the acclimation period. These conditions were maintained for seven days. In this period, on the second day, all the mice were injected intraperitoneally with sheep red blood cells (SRBC). The results of experiment two were as follows: (1) The specific humoral immune response to SRBC was investigated in terms of the number of PFC in the spleens and hemagglutination in sera, but significant differences were not found among the groups. (2) Plasma IgG levels in the Crowd-(1) were significantly higher than those in Control (p < 0.05). (3) Both superoxide production activity and phagocytic activity of neutrophils were significantly depressed in Crowd-(2) as compared with Control (p < 0.01, respectively), whereas each neutrophil function of Crowd-(1) tended to be enhanced as compared with Control.

Animals↗
PubMedDate not supplied

Crowding and mental health.

An epidemiologic investigation of the mental needs and services of 1645 respondents, aged 17 to 92 years and living in a representative southeastern county in Florida, revealed that 7.8% of the sample lived in crowded conditions. The crowded respondents scored significantly higher than did the uncrowded on both a depression scale and on the Health Opinion Survey. Associations between crowding and high scores on both scales were strongest among: respondents in the childrearing and middle years of life, blacks at all income levels, whites in the intermediate annual family income range of $6000 to $9999, and especially, females rather than males. Consistently, the crowded black population, and particularly, crowded white women, had much higher scores than did the uncrowded women. A multiple regression analysis showed that three variables--being a female, having a lower income, and crowding--accounted for 16.5% of the variance. The discussion emphasizes that the relationship between crowding and higher scores on indices of emotional distress is quite complicated. In crowded situations, depression may be a costly, semi-adaptive reaction to excessive interpersonal stimulation. Women living in crowded situations appear to be at high risk for depressive illness; their plight brings to mind the classic animal experiments which showed that the maternal behavior of females deteriorated in crowded situations.

Adolescent↗
PubMed1985

Prediction of mandibular incisor and canine crowding changes in the mixed dentition.

To test the hypothesis that preeruptive tooth positions and dental arch parameters might forecast crowding changes, a sample of 47 aboriginal children (26 males, 21 females) was selected stringently on the basis of Class 1 characteristics and an untreated dentition unaffected by caries or attrition. Crowding scores, radiographic relationships of 765E, and dental arch dimensions were evaluated for the mixed dentition (Stage 1, 8.91 +/- 1.05 years) and earliest emergence of the permanent dentition (Stage 2, 12.48 +/- 0.97 years). Changes between the stages were calculated and the sample was divided into two groups, according to an increase (Group 1) or decrease (Group 2) in incisor and canine crowding. Multivariate and multiple regression analyses were used to identify predictors (Stage 1 radiographic and dental arch parameters) of incisor and canine crowding behavior. Dental arch form and tooth size were important factors in measuring the amount of incisor or canine crowding at Stage 1 and Stage 2. Neither the radiographic nor the dental arch predictors proved useful in forecasting crowding changes. Group 2 dental arches tended to be initially narrower, shallower, and more crowded; however, they showed greater molar and canine width expansion and lessened arch depth reduction than Group 1 cases. Many cases showed a reduction in canine crowding from mixed to permanent dentition. This appeared to be largely independent of the observed incisor crowding. Sexual, racial, and individual variations in dentofacial pattern reinforce the need to carefully consider interceptive extraction or space-regaining therapy for each patient because of the unpredictability of crowding behavior during the transition from mixed to permanent dentition.

Australia↗
PubMed1989

[Gnathometric changes in examinees with and without early findings of crowding--a longitudinal study].

The longitudinal sample of children of both sexes (31 without crowding and 39 with crowding) has been investigated to examine the influence of clinically estimated findings in the deciduous dentition in the volume of jaw growth as well as in the occurrence of some malocclusions in the mixed dentition. The children were examined for the first time at the age of 4.5 and again 3 years later. The results have pointed out the following: there was no essential difference in the volume of transversal and sagittal jaw growth in reference to early findings; in both groups the significant enlargement of transversal and sagittal dimensions was recorded; mean of the width of the upper dental arch are significantly higher in the group without crowding in primary dentition; mean of the length of the upper dental arch are somewhat higher in the examinees with early findings of crowding at the first examination, namely in the examinees without early finding of crowding at the second examination; mean of the overjet are somewhat higher in the group with early finding of crowding; distribution of the examinees in the mixed dentition according the orthodontic diagnosis does not show essential differences in regard to early finding; the largest number of the examinees in the mixed dentition shows the symptoms of the primary crowding regardless of the earlier findings; only 29.1% examinees without early finding of crowding, maintain the same characteristic in the mixed dentition; in the 26.4% examinees with early finding of crowding, there comes to the spontaneous loss of the primary symptoms during the change of teeth namely to the transfer to the group with no crowding.

Child↗
PubMed1987

Crowding-induced changes in basal and stress levels of thyrotropin and somatotropin in male rats.

The effects of crowding on thyrotropin (TSH) and somatotropin (GH) secretion were studied in two-month-old male rats. Crowded rats (9-10 per cage) showed lower serum GH levels than controls (3 per cage). Likewise, serum GH was lower in crowded rats after acute exposure to stress. However, percentage inhibition of GH secretion induced by acute stress was similar in crowded and control rats. Crowding reduced the TSH response to acute stress. The results found with the administration of hypothalamic regulatory factors suggest that the impaired GH and TSH secretion observed in crowded rats was not likely to be at the pituitary level. Therefore, altered neuroendocrine control of GH and TSH secretion appears to exist in crowded rats. Preliminary results obtained in rats crowded from weaning to adulthood suggest that food restriction only partially accounts for the changes observed in crowded rats.

Animals↗
PubMed1989

Comparison of crowding and food restriction effects on growth, body weight gain and endocrine status in the rat.

The present work compares the effects of post-weaning crowding and those of food restriction on growth, body weight gain and the levels of several hormones, in male Sprague-Dawley rats. Crowding resulted in reduced food intake and diminished body weight gain. Rats daily receiving the same amount of food as that eaten by crowded rats (food-restricted group) showed similar body weight gain as crowded rats, but higher growth rate. Neither crowding nor food restriction altered the pituitary-adrenal axis. In contrast, both treatments decreased serum insulin, growth hormone (GH), somatomedin C (Sm-C) and thyroid-stimulating hormone (TSH) as compared to control rats. The reduction of GH and Sm-C levels was similar in crowded and food-restricted rats but that of TSH was higher in food-restricted, rather than in crowded rats. The present data indicate that the effects of crowding could only be partially explained by the concomittant reduction of food intake and that the serum levels of the hormones studied could not explain the differences between the crowded and food-restricted rats with regard to growth.

Animals↗
PubMed1993

Social crowding stress diminishes the pituitary-adrenocortical and hypothalamic histamine response to adrenergic stimulation.

Social stress of crowding almost totally reduced the rise in serum corticosterone elicited by intracerebroventricular administration of isoprenaline, a beta-adrenergic receptor agonist, after 3 and 7 day of crowding and substantially diminished that response after 14 and 21 days. Crowding stress totally abolished the increase in hypothalamic histamine induced by isoprenaline in control rats. Crowding also significantly diminished the increase in serum corticosterone evoked by clonidine, an alpha 2-adrenergic agonist, and abolished the clonidine-induced elevation in hypothalamic histamine levels. The stimulatory effect of phenylephrine, an alpha 1-adrenergic agonist, on corticosterone secretion was only moderately diminished in crowded rats. Neither phenylephrine nor crowding stress changed significantly the hypothalamic histamine levels. These results indicate that social stress of crowding considerably impairs the hypothalamic-pituitary-adrenocortical responsiveness to central beta- and alpha 2-adrenergic receptor stimulation. Crowding also abolishes the rise in hypothalamic histamine induced by beta- and alpha 2-adrenergic agonist, suggesting a role of hypothalamic histamine in the HPA adaptation to the social stress of crowding.

Animals↗
PubMed1977

A clinical study of the relationship between crowding of teeth, plaque and gingival condition.

A clinical trial was undertaken to assess whether crowded teeth were more likely to accumulate plaque and develop gingivitis than non-crowded teeth. A tooth was considered crowded if it was displaced by 2 mm and/or rotated 15 degrees or more from the normal position in the arch. The material consisted of 50 dental students aged 21 to 32 years. An initial examination comprised assessment of Plaque Index, Gingival Index and pocket depths. After this examination the subjects refrained from using interdental cleaning aids but continued with their normal toothbrushing for 40 days. After re-examination they were instructed in the effective use of dental floss. A final examination was carried out after 140 days. At the start of the trial no difference was found in regard to the Plaque Index between crowded and non-crowded teeth. The Gingival Index for growded front teeth, but not for crowded premolars, was somewhat higher than for the corresponding controls. The cessation of interdental cleaning resulted in a similar increase in plaque accumulation and gingival inflammation in both non-crowded and crowded teeth. The use of dental floss for approximal tooth cleaning resulted in a similar decrease in the Plaque- and Gingival Indices for both types of teeth. The results demonstrate that in a group of young adults, crowding of teeth (1) did not favour plaque accumulation on approximal tooth surfaces and (2) influenced the degree of gingival inflammation only to a minor extent.

Adult↗
PubMed1993

Psychoneuroendocrine outcomes of short-term crowding stress.

One-week exposure to crowding stress has been reported to affect body weight and pituitary-adrenal axis activity. This study has first evaluated whether the aforementioned changes are associated with altered exploratory activity. One-week crowding (16 rats/cage) diminished body weight gains, compared to the control situation (four rats/cage): actually, this difference was mainly due to a marked loss in food intake and body weight following the first day of crowding. On the other hand, 1-week crowded rats were not different from their controls when placed for the first time in an open field, as shown by the analysis of their exploratory activities, their number of grooming episodes, and their defecation. Psychoneuroendocrine effects of 1-day crowding were then investigated: actually, open field behaviors were not modified but basal plasma glucose levels were decreased. Moreover, neither plasma ACTH and corticosterone levels nor 2-min cold swim-induced increases in corticosterone levels were affected. Besides, cold swim-induced increases in plasma ACTH levels were amplified in crowded rats, and these increases were associated with hyperglycemia in crowded, but not in control rats. It is suggested that 1-day exposure to crowding has differential consequences upon feeding and exploratory behaviors while potentiating the responsiveness of stress hormones.

Adrenocorticotropic Hormone↗
PubMed1979

Disruptive effects of disconfirmed expectancies about crowding.

The experiment utilized a 2 (high vs. low room density) X 2 (forewarning of a crowded room vs. no forewarning) X 2 (simple vs. complex task) design to examine the effects of anticipation of crowding on task performance. More tasks were attempted and efficiency was higher when expectancies about the crowd were confirmed. Subjects not told to anticipate a crowd who actually worked under high density and subjects warned about a crowd that did not materialize performed most poorly. These differences were largest for the complex task. Baum and Greenberg's results were replicated with the performance data. Perceptions of the experimental room also differed as a function of anticipation, but failure to obtain a Crowding X Anticipation interaction did not support their hypothesis that anticipating a crowd induces identical perceptions to those obtained under actual crowding. The results are discussed in terms of disconfirmed expectancies being disruptive of performance, particularly complex task performance.

Adult↗
PubMed1979

Effect of crowding on amphetamine-induced disaggregation of brain polyribosomes.

DL-amphetamine's actions on brain polyribosomes were studied in crowded and uncrowded mice. The administration of 20 mg/kg DL-amphetamine induced disaggregation of brain polyribosomes in both crowded and uncrowded mice 30 min post drug administration. However, the magnitude of polysome dissociation was observed to be greater in crowded animals than in uncrowded ones. In studying the dose-response relationship there appears to be a relationship between drug dose and polysome disaggregation in both groups of animals, although the effects were always greater in crowded mice. The magnitude of polysome dissociation appears to parallel both in the intensity of central nervous system stimulation, and degree of crowding. Haloperidol was able to block the increased locomotor activity due to drug dose and crowding at 1 mg/kg, and significatnly suppress disaggregation of brain polysomes in crowded animals. A possible role of the effects of crowding on the central nervous system in the presence of amphetamine as it relates to polysome dissociation has been presented.

Amphetamine↗