Do dogs rescue their owners from a stressful situation? A behavioral and physiological assessment

Animal Cognition - Rescue behavior is considered a type of pro-social response, defined as a voluntary action directed to benefit another individual who is in a stressful or dangerous situation. In...     

Testosterone and cortisol responses to competitive fighting in human males: A pilot study

Serum testosterone and cortisol levels were measured by radioimmunoassay in 14 young male judo competitors, in samples taken 10 minutes before and 45 minutes after two different procedures. The first involved physical exercise and the second competitive fighting. Both procedures were of 5 minutes duration and sessions took place at the same time (between 10:00 A.M. and 12:00 P.M. local time) but on different days. Comparing the two situations over all subjects revealed that testosterone increased after exercise and decreased slightly after Competition. Between subject comparisons suggested that contrary to previous claims, winning or losing did not significantly change the testosterone and cortisol levels. Comparisons of subjects who were members of the Regional Team with individuals who were not part of that group confirmed that members increased their testosterone levels after competition, whereas the nonmembers showed a significant decrease. Moreover, success of the individuals, in their sporting record, correlated positively and significantly with the changes of testosterone observed during the competition. These preliminary results suggest that previous personal experience of success can influence the pattern of the psychoendocrine response to a contest situation.     

Time estimation: does the reference memory mediate the effect of knowledge of results?

This study presents evidence for the role of knowledge of results (KR) in the estimation of medium time intervals (4-12 s durations). Experiment 1 tested the hypothesis that KR operates at the same stage of temporal processing as attention. The absence of an interaction of attention and KR is taken as evidence against this hypothesis. Experiments 2 and 3 further studied the effects of KR in a reproduction and a production task, respectively. The effects of KR were small in the reproduction and substantial in the production task. The results are interpreted in terms of a clock-based timing model and the findings taken together converge on the interpretation that KR affects the reference memory (RM), rather than the other components of the model.     

False memories and lexical decision: even twelve primes do not cause long-term semantic priming

Semantic priming effects are usually obtained only if the prime is presented shortly before the target stimulus. Recent evidence obtained with the so-called false memory paradigm suggests, however, that in both explicit and implicit memory tasks semantic relations between words can result in long-lasting effects when multiple 'primes' are presented. The aim of the present study was to investigate whether these effects would generalize to lexical decision. In four experiments we showed that even as many as 12 primes do not cause long-term semantic priming. In all experiments, however, a repetition priming effect was obtained. The present results are consistent with a number of other results showing that semantic information plays a minimal role in long-term priming in visual word recognition.     

Aging and rule learning: the case of the multiplicative law

This work examined the effect of age on the ability to learn multiplicative combination rules. Participants learned the multiplicative relationship between daily tobacco intake, daily alcohol intake, and risk of esophageal cancer. The hypothesis was that younger adults would learn to implement a multiplicative combination rule and older adults would not, despite feedback. Among the younger adults, complete rule learning took place. Before receiving feedback, they used an underadditive rule, a result consistent with previous studies. After only a limited amount of feedback, they learned to use a multiplicative rule. Even after receiving feedback, however, the older adults still showed difficulties in using the multiplicative rule. These results strengthen the proposition by Chasseigne, Mullet, and Stewart (1997) that the differences between younger and older adults in function learning are related mainly to flexibility of functioning.     

Context and the interpretation of likelihood information: the role of intergroup comparisons on perceived vulnerability

Four experiments investigated how people's perceptions about a group's (e.g., women's) vulnerability to a disease are influenced by information about the prevalence of the disease in a comparable group (e.g., men). Participants read symptom and prevalence infomation about fictitious diseases before answering questions regarding target group vulnerability. Participants used the prevalence rate for a nontarget group as an immediate comparison standard for intuitively interpreting the degree of vulnerability of a target group, resulting in robust contrast effects. Experiments 3 and 4 illustrated that these contrast effects can cause a person's intuitive perceptions about a group's vulnerability to selected diseases to conflict with his or her knowledge of the prevalence rates for the diseases. The results support a distinction between 2 components of psychological uncertainty-beliefs in objective probability and more intuitive perceptions of certainty.     

Ability evaluation by proxy: role of maximal performance and related attributes in social comparison

Four experiments tested the effects of information about a proxy's related attributes and maximal effort in social comparisons of ability. In Study 1, a proxy's prior performance at maximal effort exerted systematic effects on participants' personal performance predictions for a novel task. When information about the proxy's effort was ambiguous (Study 2). information about related attribute similarity was used in the formulation of performance predictions. In Studies 3 and 4, 2-way interaction terms revealed that participants used related attribute information in generating performance predictions when the proxy's maximum effort was unknown. However, related attribute information was disregarded when proxy's maximum effort was unambiguous. Results were consistent with the proxy comparison model of ability self-evaluation (L. Wheeler, R. Martin, & J. Suls, 1997).     

Visual habituation at five months: short-term reliability of measures obtained with a new polynomial regression criterion

Using a new polynomial regression criterion, the authors investigated empirically the short-term reliability of infants' visual habituation measures. Twenty-one 5-month-old infants were tested twice with a 1-day interval. Results revealed many reliable habituation measures, a reliable reaction to novelty measure, and a new reliable measure of interest. The 2nd-order polynomial regression criterion probably produced this improvement because it uses all of the available looking time data.