The effect of timing of a perturbation on the execution of a lifting movement

Anticipation to the mass magnitude is important in lifting, but underestimation of a mass, in contrast to overestimation, does not cause major movement disturbances. This may be caused by corrections in muscle activity before the object is actually lifted. This study was designed to assess the importance of these corrections during the loading phase for the execution of a lifting movement when the mass is underestimated. Ten subjects lifted a box (1.6 kg), of which the mass was increased by 10 kg without them knowing so. The mass was added either before the box had been lifted from the ground (perturbation before lift-off, PBL) or right perturbation after lift-off (PAL). In the PBL condition back muscle activity was increased before lift-off. Even though this early corrective response could obviously not occur in the PAL condition, the lifting movement was executed without clear problems. In sum, corrections in muscle activity before lift-off are not necessary for adequate correction of a perturbation induced by an unexpected heavier object.     

(-)-9-Dehydrogalanthaminium bromide,a new cholinesterase inhibitor,enhances place and object recognition memory in young and old rats

In a previous study, we showed that (-)-9-dehydrogalanthaminium bromide, a synthetic galanthamine derivative, was more potent than galanthamine in inhibiting acetylcholinesterase. We studied here the action of this new compound on recognition memory in young and old rats, using a two-trial recognition task designed to test both place and object recognition. (-)-9-dehydrogalanthaminium bromide was injected (0.3, 1, and 3 mg/kg, i.p.) in young and old rats before the acquisition phase, immediately after it, or before the retrieval phase of the task, in order to determine the stage of information processing affected by the compound. (-)-9-dehydrogalanthaminium bromide improved both place and object recognition in young rats, via an enhancement of acquisition (3 mg/kg: place recognition; 1 and 3 mg/kg: object recognition) and consolidation (1 and 3 mg/kg) information processing. In old rats, (-)-9-dehydrogalanthaminium bromide improved performance by acting on the acquisition processes of place (0.3, 1, and 3 mg/kg) and object (1 and 3 mg/kg) recognition. These results provide information on the profile of activity of (-)-9-dehydrogalanthaminium bromide on memory processes, and suggest that this new compound could have utility in the treatment of cognitive dysfunction occurring in Alzheimer's disease or in the normal course of aging.     

A cross-linguistic data bank for oral picture naming in Dutch, English, German, French, Italian, Russian, Spanish, and Swedish (PEDOI)

The well established effect of word frequency on adult's picture naming performance is now called into question. This is particularly true for variables which are correlated with frequency, as is the case of age of word acquisition. Since the work of [Carrol and White, 1973] there is growing agreement among researchers to confer an important role in lexical access to this variable. Indeed, it has been shown ( [Hodgson and Ellis, 1998]) that for normal English-speaking adults only the variables 'age-of-acquisition' and 'name agreement' are independent predictors of naming success among the various variables considered. However, when brain-damaged subjects with and without degenerative pathologies are studied, word frequency and word length as well as concept familiarity all give significant effects ( [Hirsh and Funnell, 1995]; [Lambon Ralph et al., 1998]; [Nickels and Howard, 1995]). Finally, it has been suggested that the production of specific error types may be related to such variables. According to [Nickels and Howard, 1994] the production of semantic errors is specifically affected by 'imageability' and in the recent study by [Kremin et al., 2001] 'age of acquisition' predicts (frank) word finding difficulties.     

Direct versus indirect emotional consequences on the Iowa Gambling Task

The Iowa Gambling Task has been widely used in the assessment of neurological patients with ventro-mesial frontal lesions. The Iowa Group has claimed that the Gambling Task is too complex for participants to follow using cognition alone, so that participants must rely on emotion-based learning systems (somatic markers). The present study investigates whether similar tasks can be performed without direct somatic markers. In a 'Firefighter' task closely matched to the classic Gambling Task, participants evaluate the performance of others--so that they experience reward and punishment indirectly. In contrast to the gradual improvement in performance seen on the classic Iowa Gambling Task, participants on the Firefighter Task showed no learning effect, mirroring the performance of patients with ventro-mesial frontal lesions, and suggesting that the task is very difficult to perform without direct somatic marker information. The use of this task as empirical measure of 'empathy' are discussed.     

Social categorization and fear reactions to the September 11th terrorist attacks

Two experiments were run in The Netherlands and Belgium 1 week after the terrorist attacks against the World Trade Center in New York on September 11, 2001. The aim was to investigate whether social categorization affected emotional reactions, behavioral tendencies, and actual behaviors. Results showed that focusing participants' attention on an identity that included American victims into a common ingroup led them to report more fear and stronger fear-related behavioral tendencies and to engage more often in fear-related behaviors than when victims were categorized as outgroup members. Results are discussed with respect to appraisal theories of emotion and E. R. Smith's model of group-based emotions.     

Does social dominance generate prejudice? Integrating individual and contextual determinants of intergroup cognitions

Social dominance orientation (SDO) has been proposed as an important variable in the explanation of prejudice. We distinguish between three conceptualizations of SDO: SDO as a personality trait (personality model), SDO as a moderator of the effects of situational variables (Person x Situation model), and SDO as a mediator of the effect of social position on prejudice (group socialization model [GSM]). Four studies (N = 1.657) looking at the relations between social positions, SDO, and prejudice in a natural setting and in a laboratory setting provide strong support for the GSM. In contrast to previous correlational findings, there is evidence of a cause (dominant social position), an effect (prejudice increases), and a mediator (SDO). These results suggest new perspectives on the integration of individual and contextual determinants of prejudice.     

Political orientation and modern versus aversive racism: tests of Dovidio and Gaertner's (1998) integrated model

According to J. F. Dovidio and S. L. Gaertner's (1998) integrated model of racism, politically liberal European Americans tend to express racism differently than conservative European Americans, with liberals demonstrating aversive racism and conservatives, symbolic or modern racism. In support of the model, in Experiment 1 liberals showed bias in favor of a twice-prosecuted African American relative to a European American in their judgment of double jeopardy, whereas conservatives did the reverse. Experiment 2 replicated these effects while eliminating a confound in the design of Experiment 1. Experiment 3 found evidence for the intrapsychic conflict hypothesized to underlie aversive racism. Specifically, only liberals displayed greater physiological arousal to the touch of an African American versus a European American experimenter.     

Estimating sample-size requirements in research design: A study of intuitive statistical judgment

Subjects were given an experimental task in which they had to play the role of a quality-control researcher for a company. They had to consider a hypothetical experiment that involves testing a sample of batteries from a truck load, which may or may not be substandard. In the main experiment, subjects were given information about the prior probability of substandard truck loads (base rate), the degree of variability of battery life, and the mean difference between standard and substandard batteries, all of which are formally relevant to the decision, and they were also told the number of batteries in the truck (population size) that is formally irrelevant. The task was to decide (intuitively) how many batteries to test to achieve a specified error rate using a specified decision rule. In a second study, subjects were given a similar scenario, but asked to rate which pieces of information would be relevant to the decision. Subjects showed themselves to be sensitive to the effects of sample variability and base rate when making intuitive design decisions, though an odd effect of the mean difference factor was observed. There is also clear confirmation of a bias-to-weight sample size by population size as reported in earlier research using different kinds of judgmental tasks.