The effect of exercise on the selective performance of an instrumental response

Dogs were used to condition two instrumental reactions—bending of the left or of the right forepaw respectively. In the experimental situation a dish containing food was presented to the dog at a distance but could be drawn close and retained by lifting the forepaw to which (left or right) a lever had been attached. If both paws were simultaneously attached to levers, the dog had to choose between two reactions. Preliminary trials showed a right paw preference in spite of the equal effectiveness (food reinforcement) of the left paw. The aim of this experiment was to alter this right paw preference by a paradigm of differential practice with left paw dominance. The plan was to have ten training sessions followed by one test with choice. According to the probabilities, P_left = 0.8, P_right = 0.2, a random table was used to determine the order of the right-left paw attachments to the levers during training. In all, 1,000 training sessions and 100 tests with choice were carried out in each of three dogs. According to the training program, in every 100 training sessions the left paw had to perform the reaction a total of 80 times and 20 times by the right paw. An absolute alteration in paw preference occurred P_lelt = 1.0) even though both forepaws were equally effective in obtaining food reinforcement on the test trials. The present results indicate that not only the Law of Effect but Exercise is also important in instrumental conditioning.     

Coping as a mediator between personality and stress outcomes: a longitudinal study with cataract surgery patients

Personality and coping were specified as predictors of emotional outcomes of a mildly stressful medical procedure. Situation-specific coping was examined in contrast to dispositional coping, and it was tested whether one or the other would mediate the relationship between higher-order personality factors and stress outcomes. Cataract patients (N=110) participated at four measurement points in time during a six-week period surrounding their scheduled surgery. Dispositional coping did not mediate the personality–outcome relationship. In contrast, situation-specific coping acquired a mediator status between personality and adaptational criteria and accounted for independent outcome variance once personality traits were included as predictors in the models. Thus, the data suggest that whether or not coping mediates between personality factors and affective outcomes may be related to the methodological approaches of its operationalization. Copyright © 2005 John Wiley & Sons, Ltd.     

Defensive reactions of “wild-type” and “Domesticated” wild rats to approach and contact by a threat stimulus

Selective breeding of wild rats over many generations on the basis of low or high defensive threat and attack to human approach and contact has produced highly polarized “domesticated” and “wild-type” animals. Because the selection procedure selectively involves these two defense patterns, and these clearly differ in the two groups, it is of interest to determine if other, nonselected, defensive behaviors to threat stimuli also change. “Domesticated” and “wild-type” rats of the thirty-fifth generation were run in a fear defense test battery (F/DTB) to systematically evaluate defensive behaviors to a variety of present threat stimuli. “Domesticated” rats showed reduced avoidance and slower flight speed to an approaching experimenter, reduced jump/startle response to handelap and dorsal contact, less vocalization and boxing to vibrissae stimulation or to an anesthetized conspecific, and reduced defensiveness to an attempted pickup by the experimenter. These results indicate that selective bi-directional breeding for defensive threat and attack to human approach and contact produces group differences in a variety of defensive behaviors, and in defensiveness to stimuli other than those on which the selection was based. © 1994 Wiley-Liss, Inc.     

Getting older and living up to implicit followership theories: Implications for employee psychological health and job attitudes

Age discrimination at work is a widespread destructive phenomenon that often takes subtle forms. Based on negative stereotypes about older employees, we argue that older employees often experience that they are perceived as less ideal followers than younger employees. We propose that older and younger employees do not differ in what they assume their supervisors expect of an ideal follower (implicit followership theories, IFTs). Thus, we hypothesize that older employees perceive that they compare less favorably to their supervisors' IFTs than younger employees (i.e., worse IFT-fit). This should entail lower quality of the relationship between leader and follower (leader-member-exchange, LMX), which, in turn, should have detrimental effects on employees' health (i.e., burnout) and job attitudes (i.e., job satisfaction, turnover intentions, and identification). We tested our model in a field study with 379 employees. Results differed for ideal and counter-ideal follower attributes. Concerning counter-ideal follower attributes (e.g., being incompetent), age had the proposed negative effect on psychological health and job attitudes that mediated through IFT-fit and LMX. Concerning ideal follower attributes (e.g., thinking ahead), older employees expected their supervisors not only to think less of them than of their younger colleagues, but also expected them to have less demanding IFTs—contrary to our expectations. Employee age was negatively related to psychological health and job attitudes, mediated through lower perceived IFTs, worse perceived appraisal of the actual employee and their joint effects on LMX.     

Predatory aggression in the mink (Mustela vison): Roles of serotonin and food satiation

5-Hydroxytrypotophan at a dose of 50 mg/kg intraperitoneally (i.p.) sharply increased neural serotonin (5-HT) levels in mink and considerably inhibited that animal's predatory attack on rats. Intraperitoneal injection of 5-HT (10 and 20 mg/kg) did not influence such rat-killing. Neural levels of 5-HT or 5-hydroxyindoleacetic acid (5-HIAA) and subsequent aggression by the predator did not change to any great degree after ingestion of a single meal. Abundance of natural mink food for 3 days was associated with an increased level of 5-HIAA in the lateral hypothalamus and the amygdala as well as with an increased latency to attack and to kill rats. 5-HT seems to represent an endogenous factor that inhibits predatory attack by the mink; this effect appears to function through increased metabolism of 5-HT in some brain regions, which is evident after abundant intake of tryptophan with the natural diet.     

The effects of gendered information in stories on preschool children’s development of gender stereotypes

Social-cognitive theory posits that children learn gender stereotypes through gendered information. The present study examined whether children learn new gender stereotypes from stories when unknown words are linked to a gendered protagonist or context information. In Experiment 1, 40 3- to 6-year-old preschoolers were read stories with either a gendered protagonist embedded within a non-gendered context, or a non-gendered protagonist embedded within a gendered context. In Experiment 2, the same sample of children were read stories with the protagonist and the context displaying congruent or incongruent gender information. Each story featured an unknown activity linked with the stereotypical content. Both experiments indicate that the children rated the activity according to both the gender of the context and of the protagonist; however, the effect of the latter was stronger. In addition, children showed higher interest in the unknown activity if the protagonist’s gender matched their own sex. Thus, gender information in stories influences how children perceive unknown words.     

The utility of ground rule instructions with younger and older adult witnesses

This study examined the effectiveness of ground rules—simple instructions outlining the communication expectations of an investigative interview—with 73 younger (age 18–40) and 57 older (age 60+) adults. Participants watched a film depicting an implied sexual assault and were interviewed after a brief delay. One third received no ground rules, one third received ground rules as statements, and one third received the statements along with practice examples. The interview contained questions that required participants to apply one of the rules. Those who received ground rules were asked their perceptions of the rules. Results demonstrated that practicing ground rules improved response quality to problematic recognition questions, younger adults showed more variability in responses to different ground rules than older adults, and most participants found ground rule instructions useful in investigative interviews. Results provide support for the use of ground rules in interviews with adult witnesses.     

高低水平汉英二语者阅读难易英语句子的知觉广度

通过考察高、低水平汉英二语者阅读难易英语句子的知觉广度,本研究发现二语水平和句子难度调节汉英二语者的英语阅读速度,但不影响其阅读知觉广度,均表现为注视词左侧1个词至右侧1个词。该结果表明汉英二语者采用相对固定的注意分配策略来阅读英语,与中央凹加工负荷假说不一致。     

The effect of similarity between elemental stimuli and compounds in olfactory patterning discriminations

We studied the ability of honeybees to discriminate between single odorants and binary olfactory mixtures. We analyzed the effect of the number of common elements between these two stimulus classes on olfactory discrimination. We used olfactory conditioning of the honeybees' proboscis extension reflex (PER), a paradigm in which odors can be associated with a reinforcement of sucrose solution. Bees were asked to discriminate reinforced from nonreinforced olfactory stimuli. They were trained with two elemental odors (A and B) versus a binary olfactory mixture. The mixture was either AB (group 2CE, two common elements), AC (group 1CE, one common element A), or CD (group 0CE, no common element). Three groups followed a positive patterning schedule (mixture reinforced and elements nonreinforced: groups 2CE+, 1CE+, and 0CE+) and three other groups a negative patterning schedule (mixture nonreinforced and elements reinforced: groups 2CE-, 1CE-, and 0CE-). We showed that a reduction of similarity (number of common elements) between elemental odors and compounds enhanced the ability to discriminate elements from compounds and that the kind of compound processing used by the bees supports theories that assume nonelemental compound processing (i.e., that exclude the mere summation of the elemental associative strengths upon compound presentation).