Social organization predicts nature of infant-adult interactions in two species of wild guinea pigs (Cavia aperea and Galea monasteriensis)

The authors compared interactions of infants with mothers and unfamiliar females in a novel environment in 2 caviomorph rodent species: the harem-living Cavia aperea, the probable progenitor of the domestic guinea pig; and the pair-living Galea monasteriensis. In C. aperea, interactions with mothers and unfamiliar females were largely similar; in G. monasteriensis, interactions with the mother, but not unfamiliar female, were characterized by physical closeness and sociopositive behavior. In G. monasteriensis, plasma cortisol levels were lower when with the mother than when with the unfamiliar female. Results are consistent with the species' social organizations and suggest that behavioral interactions of pups with mothers and other females in domestic guinea pigs reflect primarily the social organization of the progenitor species rather than domestication.     

Memory failures appraisal in younger and older adults: role of individual difference and event outcome variables

The authors examined the role of individual difference and event outcome variables in younger and older adults' memory failures appraisal. Participants read vignettes that described fictitious younger characters (in their 20s-30s) or older characters (in their 60s-70s) who had experienced a minor or severe consequence of their forgetfulness. The authors solicited attribution ratings on the potential causes of the forgetfulness and memory opinion ratings. Younger and older adults' ratings were largely similar, although age differences occurred on the effort and luck attribution scales. The consequences of the forgetting had a sizable impact on both the attribution and memory opinion ratings. Individual differences in self-reported memory had a relatively small impact on causal attribution and memory opinion ratings. These results suggested that people weigh their judgments of fictitious forgetful characters against event outcomes more so than ageist beliefs that portray a negative image of cognitive competence in later life.     

GENDER-RELATED PATTERNS OF HELPING AMONG FRIENDS

In this study, the social role theory of gender and helping (Eagly & Crowley, 1986) was applied to understand gender differences in helping behavior. Relationships among criterion variables of time spent helping and help quality; and key predictors of problem severity, empathic tendency, anger, sympathy, closeness, causal controllability, coping, and self-efficacy were applied. Participants from a large community sample ( N = 1,004) described situations in which they helped a friend and completed questionnaires describing factors that influenced their actions. Recipients of the help also filled out similar questionnaires. It was found that across many problem settings women spend more time helping, give higher quality help, and feel more empathy and sympathy in response to their friends' problems. Further, the presence of anger toward a friend is associated with more time spent helping but a lower quality of help. In contrast, men rate their friends' problems as more controllable/blameworthy and experience more anger. Further, controllability has a greater influence on a number of help-related variables. For both men and women, self-efficacy and perception of problem severity are the greatest direct predictors of helping.     

Age and skilled performance: contributions of working memory and processing speed

In this study, we examined the interrelationships among age, working memory (WM), processing speed, and the development of skilled performance. Younger (M=20.5) and older (M=68.9) adults were trained on an alphabet arithmetic task (Haider & Frensch, 1996) administered across three consecutive days. Although older adults were slower than younger adults, both age groups' response latencies decreased as a result of practice. Contrary to expectations, WM and processing speed were significantly correlated with performance late in training. Partial correlations suggested that age differences in performance at the end of training were mediated by individual differences in cognitive processing speed.     

A computerized test of speed of language comprehension unconfounded by literacy

A computerized version of the Silly Sentences task developed for use with children is found to be equivalent to the pencil‐and‐paper version from the SCOLP test with UK undergraduates, and is usable by a sample of young UK children. Because the sentences are presented aloud instead of being written, the computerized test is not affected by literacy skills. Translated into Kiswahili, the task was used in Tanzanian schools, despite the absence of an electricity supply and a very different cultural background. The decision latencies had a test–retest reliability of 0.69 over 5 months, and were independent of age and baseline decision speed. The task appears appropriate for longitudinal studies, including those in developing countries. Given its simplicity and the correlations with the original SCOLP version of the task, it may also be useful in studies on literate adults. Copyright © 2001 John Wiley & Sons, Ltd.     

Distinguishing indeterminate belief from “risk-averse” preferences

I focus my discussion on the well-known Ellsberg paradox. I find good normative reasons for incorporating non-precise belief, as represented by sets of probabilities, in an Ellsberg decision model. This amounts to forgoing the completeness axiom of expected utility theory. Provided that probability sets are interpreted as genuinely indeterminate belief (as opposed to “imprecise” belief), such a model can moreover make the “Ellsberg choices” rationally permissible. Without some further element to the story, however, the model does not explain how an agent may come to have unique preferences for each of the Ellsberg options. Levi (1986, Hard choices: Decision making under unresolved conflict. Cambridge, New York: Cambridge University Press) holds that the extra element amounts to innocuous secondary “risk” or security considerations that are used to break ties when more than one option is rationally permissible. While I think a lexical choice rule of this kind is very plausible, I argue that it involves a greater break with xpected utility theory than mere violation of the ordering axiom.