On the perception of religious group membership from faces

Background

The study of social categorization has largely been confined to examining groups distinguished by perceptually obvious cues. Yet many ecologically important group distinctions are less clear, permitting insights into the general processes involved in person perception. Although religious group membership is thought to be perceptually ambiguous, folk beliefs suggest that Mormons and non-Mormons can be categorized from their appearance. We tested whether Mormons could be distinguished from non-Mormons and investigated the basis for this effect to gain insight to how subtle perceptual cues can support complex social categorizations.

Methodology/Principal Findings

Participants categorized Mormons'' and non-Mormons'' faces or facial features according to their group membership. Individuals could distinguish between the two groups significantly better than chance guessing from their full faces and faces without hair, with eyes and mouth covered, without outer face shape, and inverted 180°; but not from isolated features (i.e., eyes, nose, or mouth). Perceivers'' estimations of their accuracy did not match their actual accuracy. Exploration of the remaining features showed that Mormons and non-Mormons significantly differed in perceived health and that these perceptions were related to perceptions of skin quality, as demonstrated in a structural equation model representing the contributions of skin color and skin texture. Other judgments related to health (facial attractiveness, facial symmetry, and structural aspects related to body weight) did not differ between the two groups. Perceptions of health were also responsible for differences in perceived spirituality, explaining folk hypotheses that Mormons are distinct because they appear more spiritual than non-Mormons.

Conclusions/Significance

Subtle markers of group membership can influence how others are perceived and categorized. Perceptions of health from non-obvious and minimal cues distinguished individuals according to their religious group membership. These data illustrate how the non-conscious detection of very subtle differences in others'' appearances supports cognitively complex judgments such as social categorization.     

The effect of membrane lipid perturbers on survival of mammalian cells to cold

Butylated hydroxytoluene (BHT), an antioxidant and common food additive, is an organic soluble molecule which modifies the properties of lipid bilayers and biological membranes. Adamantane and its derivatives, although structurally quite different, have similar effects on membranes. When Chinese hamster lung cells (V79) were pretreated with 0.1 mm BHT before exposure to +5 °C for up to 12 days in suspension culture or attached to plastic, significant protection, as assessed by colony survival, was observed compared to controls. No protection was observed when the cells were exposed to +20 °C. Use of adamantane or 2-adamantanone in serum-free medium in suspension culture at +5 °C showed protection of cells as good as, or better than, that provided by the addition of serum to control cells. Experiments with synchronized cells indicated that BHT protected cells in all phases of the cell cycle against the effects of exposure to +5 °C. However, the protection was greatest in G₁ and early S phase. Exposure of cells containing BHT to +20 °C resulted in no preferential protection in any phase of the cell cycle.     

Membrane lipid fluidity as rate limiting in the concanavalin A-mediated agglutination of pyBHK cells

The initial rate of concanavalin A-mediated agglutination of polyoma transformed Baby Hamster Kidney (pyBHK) cells follows Arrhenius kinetics. There is a smooth decrease in the agglutination rate from 37°C to 22°C with an activation energy of $\text{11.8 ± 0.2}\text{kcal/mol}$ in this region. There is a sharp decrease in agglutination rate below 22°C. The addition of 0.1 mM 1,3-di-tert-2-hydroxyl-5-methylbenzene, a lipid perturber, increases the agglutination rate by a factor of two and increases the membrane lipid fluidity as determined by the spin label method. The rotational correlation time of the spin label 2N14 $\text{(2,2-}\text{dimethyl-5-dodecyl-5-methyloxazolidine}\text{-N-}\text{oxide}$) was measured. The sum of the enthalpy of activation of rotational diffusion and the enthalpy of activation of translational diffusion is very nearly equal to the enthalpy of activation of agglutination. This is consistent with the rate limiting step of agglutination being receptor diffusion, which is probably limited in pyBHK cells by membrane lipid fluidity.     

Flow cytometry‐based enrichment for cell shape mutants identifies multiple genes that influence Helicobacter pylori morphology

The helical cell shape of Helicobacter pylori is highly conserved and contributes to its ability to swim through and colonize the viscous gastric mucus layer. A multi‐faceted peptidoglycan (PG) modification programme involving four recently characterized peptidases and two accessory proteins is essential for maintaining H. pylori's helicity. To expedite identification of additional shape‐determining genes, we employed flow cytometry with fluorescence‐activated cell sorting (FACS) to enrich a transposon library for bacterial cells with altered light scattering profiles that correlate with perturbed cell morphology. After a single round of sorting, 15% of our clones exhibited a stable cell shape defect, reflecting 37‐fold enrichment. Sorted clones with straight rod morphology contained insertions in known PG peptidases, as well as an insertion in csd6, which we demonstrated has ld ‐carboxypeptidase activity and cleaves monomeric tetrapeptides in the PG sacculus, yielding tripeptides. Other mutants had only slight changes in helicity due to insertions in genes encoding MviN/MurJ, a protein possibly involved in initiating PG synthesis, and the hypothetical protein HPG27_782. Our findings demonstrate FACS robustly detects perturbations of bacterial cell shape and identify additional PG peptide modifications associated with helical cell shape in H. pylori.     

Democrats and Republicans Can Be Differentiated from Their Faces

Background

Individuals'' faces communicate a great deal of information about them. Although some of this information tends to be perceptually obvious (such as race and sex), much of it is perceptually ambiguous, without clear or obvious visual cues.

Methodology/Principal Findings

Here we found that individuals'' political affiliations could be accurately discerned from their faces. In Study 1, perceivers were able to accurately distinguish whether U.S. Senate candidates were either Democrats or Republicans based on photos of their faces. Study 2 showed that these effects extended to Democrat and Republican college students, based on their senior yearbook photos. Study 3 then showed that these judgments were related to differences in perceived traits among the Democrat and Republican faces. Republicans were perceived as more powerful than Democrats. Moreover, as individual targets were perceived to be more powerful, they were more likely to be perceived as Republicans by others. Similarly, as individual targets were perceived to be warmer, they were more likely to be perceived as Democrats.

Conclusions/Significance

These data suggest that perceivers'' beliefs about who is a Democrat and Republican may be based on perceptions of traits stereotypically associated with the two political parties and that, indeed, the guidance of these stereotypes may lead to categorizations of others'' political affiliations at rates significantly more accurate than chance guessing.     

Biosynthesis of sex pheromone components from linolenic acid in arctiid moths

Sex pheromone components of two species of arctiid moths, Estigmene acrea and Phragmatobia fuliginosa, were shown to be derived from linolenic acid. Female pupae were injected with radiolabeled malonic acid or an 18-, 20-, 21-, or 22-carbon triunsaturated fatty acid, and the pheromone components from emerged adults analyzed for radioactivity. The data support a biosynthetic pathway in which the 21-carbon pheromone component,(Z, Z)-3,6-cis-9,10-epoxyheneicosadiene, of these moths is produced by chain elongation of linolenic acid to docosatrienoic acid with subsequent reductive decarboxylation. The 18-carbon aldehyde components,(Z, Z)-9,12-octadecadienal and (Z, Z, Z)-9,12,15-octadecatrienal, of E. acrea are produced from linoeic and linolenic acids directly. No detectable amounts of intermediate 20-, 21-, or 22-carbon fatty acid precursors were found in the gland of E. acrea.     

Long-range changes in a protein antigen due to antigen-antibody interaction.

Amide exchange kinetics were used to probe the conformation of hen egg-white lysozyme complexed with the anti-lysozyme monoclonal antibody HyHEL-5. Following the technique developed by Paterson et al. [(1990) Science 249, 755-759] we used two-dimensional NMR to measure amide exchange kinetics of the lysozyme amide protons in the lysozyme-antibody complex. A total of 15 amide protons showed altered exchange kinetics in the presence of the complex. Five of these 15 protons reside on residues that are found within the epitope as defined by X-ray crystallography. Five residues are located at the perimeter of the epitope. The remaining five residues are removed from the epitope. The perturbation of amide exchange rates at sites distant from the epitope indicates that the formation of antigen-antibody complexes can produce changes in the antigen at sites that are quite distant from the structural epitope.     

Structural and kinetic studies of the Fab fragment of a monoclonal anti-spin label antibody by nuclear magnetic resonance

Nuclear magnetic resonance has been used to study the structure of the anti-spin label antibody AN02 combining site and kinetic rates for the hapten-antibody reaction. The association reaction for the hapten dinitrophenyl-diglycine (DNP-diGly) is diffusion-limited. The activation enthalpy for association, 5.1 kcal/mol, is close to the activation enthalpy for diffusion in water. Several reliable resonance assignments have been made with the aid of recently reported crystal structure. Structural data deduced from the nuclear magnetic resonance (n.m.r.) spectra compare favorably with the crystal structure in terms of the combining site amino acid composition, distances of tyrosine residues from the unpaired electron of the hapten, and residues in direct contact with the hapten. Evidence is presented that a single binding site region tyrosine residue can assume two distinct conformations on binding of DNP-diGly. The AN02 antibody is an autoantibody. Dimerization of the Fab fragments is blocked by the hapten DNP-diGly. The n.m.r. spectra suggests that some of the amino acid residues involved in the binding of the DNP-hapten are also involved in the Fab dimerization.