A computer‐mediated communication system (CMCS) was used to explore the effects of de‐individuation on group polarization. Reicher (1984) argued that de‐individuating members of a group should increase the salience of group identity and hence normative behaviour, while de‐individuating subjects treated as individuals should have the reverse effect. We extended this idea to the group polarization paradigm and in addition independently manipulated group salience and de‐individuation, which were confounded factors in Reicher's study. It was reasoned that the visual anonymity created by isolating discussants in separate rooms would be de‐individuating compared to seating them together in the same room. At the same time either the subject's group or individual identity was made salient. A computer‐mediated communication system provided text‐based communication for discussants in all four conditions. Assuming that group polarization reflects conformity to a group norm (Turner, Hogg, Oakes, Reicher & Wetherell, 1987), we predicted an interaction between the de‐individuation and group salience factors, such that greatest polarization in the direction of a pre‐established group norm would be obtained in the de‐individuated—group condition and least in the de‐individuated—individual condition. This prediction was confirmed. Explanations of the findings in terms of Reicher's earlier study and in terms of self‐attention processes are considered within the general framework of social identity theory. Finally, the relevance of this research to the realm of human communication via computer networks is evaluated.

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The Social Identity Model of Deindividuation Effects (SIDE) proposes that depersonalization of self and others is responsible for the effects of visual anonymity on group behavior. The authors investigated these mediating processes by assessing the effects of group-based self-categorization and stereotyping of others on group attraction within visually anonymous or video-identifiable groups communicating via computer. Structural equation modeling showed that visual anonymity increased group-based self-categorization, which directly increased attraction to the group and indirectly increased group attraction by enhancing group-based stereotyping of others.Visual anonymity had no effect on self-categorization in terms of a wider social category (nationality). Predictions derived from alternative perspectives that visual anonymity decreases group attraction by increasing impersonal task focus or by attenuating evaluation concerns were not supported.

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Platelets sequester angiogenesis regulatory proteins which suggests an avenue for developing biomarkers to monitor disease. We describe a comparison of angiogenesis regulatory proteins found in platelets of colorectal cancer patients and normal controls. Platelet and plasma content of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), platelet derived growth factor (PDGF), platelet factor 4 (PF4), thrombospondin-1 (TSP-1) and endostatin in 35 patients with colon cancer were compared with 84 age-matched healthy controls using ELISAs. We standardized the platelet preparation procedure, introduced process controls and normalized the respective protein levels to platelet numbers using an actin ELISA. Statistically significant differences were found in the median levels of VEGF, PF4 and PDGF in platelets of patients with cancer compared to healthy individuals. Platelet concentrations in cancer patients versus controls were: VEGF 1.3 versus 0.6 pg/10(6), PF4 18.5 versus 9.4 ng/10(6), and PDGF 34.1 versus 21.0 pg/10(6). Multivariable logistic regression analysis indicated that PDGF, PF4 and VEGF were independent predictors of colorectal carcinoma and as a set provided statistically significant discrimination (area under the curve = 0.893, P < .0001). No significant differences were detected for bFGF, endostatin, or TSP-1. Reference Change Value analysis determined that the differences seen were not clinically significant. Plasma levels yielded no correlations.