CiteULike: Author Wedell

Sex-typed toy play behavior correlates with the degree of prenatal androgen exposure assessed by CYP21 genotype in girls with congenital adrenal hyperplasia.

A Nordenström — 2008-05-23T21:52:28-00:00

The Journal of clinical endocrinology and metabolism, Vol. 87, No. 11. (November 2002), pp. 5119-5124.

Previous studies have shown that girls with congenital adrenal hyperplasia (CAH), a syndrome resulting in overproduction of adrenal androgens from early fetal life, are behaviorally masculinized. We studied play with toys in a structured play situation and correlated the results with disease severity, assessed by CYP21 genotyping, and age at diagnosis. Girls with CAH played more with masculine toys than controls when playing alone. In addition, we could demonstrate a dose-response relationship between disease severity (i.e. degree of fetal androgen exposure) and degree of masculinization of behavior. The presence of a parent did not influence the CAH girls to play in a more masculine fashion. Four CAH girls with late diagnosis are also described. Three of the four girls played exclusively with one of the masculine toys, a constructional toy. Our results support the view that prenatal androgen exposure has a direct organizational effect on the human brain to determine certain aspects of sex-typed behavior.

Looking and Weighting in Judgment and Choice,

Douglas Wedell — 2008-05-09T20:25:05-00:00

Organizational Behavior and Human Decision Processes, Vol. 70, No. 1. (April 1997), pp. 41-64.

A sampling model was proposed in which the weight given to a piece of information corresponds to the amount of sampling of that information in either a continuous, discrete or strategic manner. These three sampling processes were related to process tracing measures of initial and additional time per acquisition and frequency of acquisition. The applicability of the sampling model was tested in three experiments in which students uncovered information corresponding to verbal and math aptitude scores of hypothetical applicants and either judged the likelihood of success in a designated major or chose which of a pair of applicants was more likely to succeed in the major. Task focus was manipulated by altering the designated major. In Experiment 1, analysis of judgment data demonstrated large effects of task focus on the weighting of verbal and math scores and corresponding increases in number of acquisitions and time per acquisition on the information receiving more weight. In Experiments 2 and 3, analyses of choice proportions revealed effects of task focus on weight and bias parameters. Looking data in choice provided strong support for two of the stages of processing described by Russo and Leclerc (1994). Initial looks reflected orientation and screening functions and additional looks reflected more evaluative processes. Experiment 3 also explored similarities and differences among groups of participants who were classified as following different identifiable choice strategies.

Oviposition plant preference and offspring performance in the comma butterfly: correlations and conflicts

Sören Nylin — 2008-04-17T09:09:18-00:00

Entomologia Experimentalis et Applicata, Vol. 80, No. 1. (1 July 1996), pp. 141-144.

Information Presentation Constraints and the Adaptive Decision Maker Hypothesis

Stuart Senter — 2008-04-02T20:44:15-00:00

Journal of Experimental Psychology: Learning, Memory and Cognition, Vol. 25, No. 2. (1 March 1999), pp. 428-446.

Participants examined sets of apartments described along 4 dimensions. Attribute values were manipulated to provide a way to infer strategy from response patterns. Experiment 1 established baseline behavior in unconstrained search, whereas Experiments 2–4 constrained participants to search either by alternative or by dimension. Dimensionwise presentation resulted in higher accuracy and reduced looking times. In 3-alternative choice, there was no evidence that strategy use depended on constraint condition. Evidence for possible strategy differences across constraint conditions was found when either multiple judgments rather than a single choice had to be made or the number of alternatives was increased to 5. These results supported features of the adaptive decision maker hypothesis (J. W. Payne, J. R. Bettman, & E. J. Johnson, 1988) but suggested that strategy use is not always strongly linked to acquisition pattern.

DO WOLBACHIA-ASSOCIATED INCOMPATIBILITIES PROMOTE POLYANDRY?

Fleur — 2008-03-11T12:37:51-00:00

Evolution, Vol. 62, No. 1. (2008), pp. 107-122.

The genetic incompatibility avoidance hypothesis as an explanation for the polyandrous mating strategies (mating with more than one male) of females of many species has received significant attention in recent years. It has received support from both empirical studies and a meta-analysis, which concludes that polyandrous females enjoy increased reproductive success through improved offspring viability relative to monandrous females. In this study we investigate whether polyandrous female Drosophila simulans improve their fitness relative to monandrous females in the face of severe Wolbachia-associated reproductive incompatibilities. We use the results of this study to develop models that test the predictions that Wolbachia should promote polyandry, and that polyandry itself may constrain the spread of Wolbachia. Uniquely, our models allow biologically relevant rates of incompatibility to coevolve with a polyandry modifier allele, which allows us to evaluate the fate of the modifier and that of Wolbachia. Our empirical results reveal that polyandrous females significantly reduce the reproductive costs of Wolbachia, owing to infected males being poor sperm competitors. The models show that this disadvantage in sperm competition can inhibit or prevent the invasion of Wolbachia. However, despite the increased reproductive success obtained by polyandrous females, the spread of a polyandry modifier allele is constrained by any costs that might be associated with polyandry and the low frequency of incompatible matings when Wolbachia has reached a stable equilibrium. Therefore, although incompatibility avoidance may be a benefit of polyandry, our findings do not support the hypothesis that genetic incompatibilities caused by Wolbachia promote the evolution of polyandry.

Memory for spatial location: cue effects as a function of field rotation.

S Fitting — 2007-12-10T15:45:05-00:00

Mem Cognit, Vol. 35, No. 7. (October 2007), pp. 1641-1658.

We developed theoretical extensions of Huttenlocher, Hedges, and Duncan's (1991) category-adjustment model of human spatial memory to incorporate the use of fuzzy boundariesand cue-determined prototypes. In two experiments, people reproduced locations of dots in a circle, while the number of external reference cues varied. In Experiment 1, the task field was stable and results were consistent with the use of fixed categories unaffected by number of cues. In Experiment 2, the task field was made dynamic by rotation on most trials, with results evaluated for nonrotation trials. The large cue effects observed for angular bias were consistent with the proposed cue-based fuzzy-boundary model. Large cue effects were also observed for absolute error, consistent with a model in which proximity to cues predicts stability of memory. Results point to the key role of orientation to the task environment in determining whether categorical encoding is based on cues.

Extraordinary Flux in Sex Ratio

Sylvain Charlat — 2007-07-13T23:27:11-00:00

Science, Vol. 317, No. 5835. (13 July 2007), 214.

The ratio of males to females in a species is often considered to be relatively constant, at least over ecological time. Hamilton noted that the spread of "selfish" sex ratio-distorting elements could be rapid and produce a switch to highly biased population sex ratios. Selection against a highly skewed sex ratio should promote the spread of mutations that suppress the sex ratio distortion. We show that in the butterfly Hypolimnas bolina the suppression of sex biases occurs extremely fast, with a switch from a 100:1 population sex ratio to 1:1 occurring in fewer than 10 generations. 10.1126/science.1143369

Bias in spatial memory: a categorical endorsement.

DB Haun — 2006-04-11T12:14:44-00:00

Acta Psychol (Amst), Vol. 118, No. 1-2. (b 2005), pp. 149-170.

Two experiments investigated how angular estimates reflect bias as a function of response mode, geometric plane of variation, number of implicit categories, memory load and intervening task conditions. In Experiment 1, participants made motor and verbal estimates of incline and azimuth from memory. Estimates in both response modes showed signs of bias predicted by a single-category adaptation of Huttenlocher et al. [Huttenlocher, J., Hedges, L. V., & Duncan, S. (1991). Categories and particulars: Prototype effects in estimating spatial location. Psychological Review, 98, 352-376] category-adjustment model. In Experiment 2, participants made motor estimates of azimuth from memory under a variety of conditions. Stimuli in this experiment were distributed along two contiguous spatial categories. Although increasing levels of cognitive load did not produce a graded effect, participants' estimates were biased and were well described by a multiple-category adaptation of the category-adjustment model. Results from both studies supported an implicit region-based model of bias in spatial memory. These findings were discussed with respect to accounts of spatial memory that propose multiple systems or formats for coding.

Evolutionary conflict: sperm wars, phantom inseminations.

SR Dall — 2005-10-26T04:22:32-00:00

Curr Biol, Vol. 15, No. 19. (11 October 2005)

A new experimental study has provided the first definitive evidence for conditional punishment of 'cheats' in a sperm-trading simultaneous hermaphrodite: the sea slug Chelidonura hirundinina. This also provides a rare unequivocal example of conditional reciprocity averting a 'tragedy of the commons' in biology.