Simultaneously cooperative, but serially antagonistic: a neuropsychological study of diagonistic dyspraxia in a case of Marchiafava-Bignami disease

We describe a patient with Marchiafava-Bignami disease who showed, in addition to signs of callosal interruption, a peculiar form of diagonistic dyspraxia. Unlike the typical diagonistic dyspraxia, both of the patient's hands could simultaneously cooperate in a sequence of bimanual actions. More specifically, his right hand could start a commanded action with the cooperation of his left hand. However, once the action was completed, his left hand started an antagonistic action, undoing the result, with the cooperation of his right hand. Once this countermanding action was completed, the original action started again. These antagonistic actions repeated themselves alternately unless he was restrained. The patient's diagonistic dyspraxia was apparent in only some bimanual actions, and he showed no diagonistic dyspraxia when performing voluntary actions; the antagonistic actions occurred in response to oral commands or by imitation. Magnetic resonance imaging showed symmetrical demyelination with partial necrosis in the genu, body, and anterior splenium of the corpus callosum. We speculate that the bimanual coordination is possible because part of the corpus callosum is intact, whereas the antagonistic actions may be caused by conflict between the two hemispheres due to interhemispheric disinhibition elicited by the demyelinated part of the corpus callosum.     

Homogeneity perception as a reaction to identity threat: effects of status difference in a simulated society game

The present study examined how members of low status groups would react to a threat to their social identity. Undergraduates participated in a ‘simulated society game,’ and were divided into four groups, each of which was assigned either a high or low status. During a series of game sessions with intergroup competition and cooperation, participants estimated the range of distributions among in‐ group and out‐group members regarding various traits. The central tendency and variability derived from each estimate were analysed. Members of the low status groups deprecated their in‐group with respect to a status‐defining trait, but showed in‐group favouritism regarding alternative, status‐irrelevant traits. Furthermore, the low status members judged their in‐group as more homogeneous than the out‐group regarding the alternative traits, particularly when they were compared to a high status group. The results were interpreted as an indication of a subtle form of maintaining positive in‐group evaluations. Theoretical and methodological implications for the study of status effects are discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

The influence of the response–stimulus interval on implicit and explicit learning of stimulus sequence

Three experiments investigated the influence of the response-stimulus interval (RSI) on implicit and explicit learning of stimulus sequences. Participants responded to numerals presented in predetermined positions with alternating long and short RSIs. Half of the participants were instructed explicitly to learn the position sequence. In the transfer phase of Experiments 1 and 2, changing RSI patterns reduced the expression of incidental and intentional learning of position sequence. In Experiment 3 the position sequence was transformed, except that sub-sequences demarcated by long RSIs remained unchanged; this greatly reduced the expression of intentional learning, and slightly reduced that of incidental learning. These results indicate that in implicit learning, stimulus sequences are learned under the constraints of RSIs, whereas in explicit learning, learning independent of RSIs, as well as learning constrained by RSIs, occurs.     

Japanese normative set of 359 pictures

This study provides Japanese normative measures for 359 line drawings, including 260 pictures (44 redrawn) taken from Snodgrass and Vanderwart (1980). The pictures have been standardized on voice key naming times, name agreement, age of acquisition, and familiarity. The data were compared with American, Spanish, French, and Icelandic samples reported in previous studies. In general, the correlations between variables in the present study and those in the other studies were relatively high, except for name agreement. Naming times were predicted in multiple regression analyses by name agreement. The full set of the norms and the new pictures may be downloaded from www.psychonomic.org/archive/.     

Word recognition reflects dimension-based statistical learning

Speech processing requires sensitivity to long-term regularities of the native language yet demands listeners to flexibly adapt to perturbations that arise from talker idiosyncrasies such as nonnative accent. The present experiments investigate whether listeners exhibit dimension-based statistical learning of correlations between acoustic dimensions defining perceptual space for a given speech segment. While engaged in a word recognition task guided by a perceptually unambiguous voice-onset time (VOT) acoustics to signal beer, pier, deer, or tear, listeners were exposed incidentally to an artificial "accent" deviating from English norms in its correlation of the pitch onset of the following vowel (F0) to VOT. Results across four experiments are indicative of rapid, dimension-based statistical learning; reliance on the F0 dimension in word recognition was rapidly down-weighted in response to the perturbation of the correlation between F0 and VOT dimensions. However, listeners did not simply mirror the short-term input statistics. Instead, response patterns were consistent with a lingering influence of sensitivity to the long-term regularities of English. This suggests that the very acoustic dimensions defining perceptual space are not fixed and, rather, are dynamically and rapidly adjusted to the idiosyncrasies of local experience, such as might arise from nonnative-accent, dialect, or dysarthria. The current findings extend demonstrations of "object-based" statistical learning across speech segments to include incidental, online statistical learning of regularities residing within a speech segment.     

Role models in self-esteem of college women

This study examined the relationship between self-esteem and the existence of role models among a sample of 36 female college students. Participants completed a questionnaire which included demographic questions, the Self-esteem Inventory, and questions concerning use of childhood and contemporary role models. Independent t-test results indicated that participants who reported having current role models had higher self-esteem scores than participants who did not, suggesting that role models may contribute to higher self-esteem in college-age women. No significant differences in self-esteem were by sex of the role model.     

Mechanisms and the current state of transcranial magnetic stimulation

Transcranial magnetic stimulation (TMS) is unique among the current brain stimulation techniques because it is relatively non-invasive. TMS markedly differs from vagus nerve stimulation, deep brain stimulation and magnetic seizure therapy, all of which require either an implanted prosthesis or general anesthesia, or both. Since its rebirth in its modern form in 1985, TMS has already shown potential usefulness in at least three important domains-as a basic neuroscience research instrument, as a potential clinical diagnostic tool, and as a therapy for several different neuropsychiatric conditions. The TMS scientific literature has now expanded beyond what a single summary article can adequately cover. This review highlights several new developments in combining TMS with functional brain imaging, using TMS as a psychiatric therapy, potentially using TMS to enhance performance, and finally recent advances in the core technology of TMS. TMS' ability to non-invasively and focally stimulate the brain of an awake human is proving to be a most important development for neuroscience in general, and neuropsychiatry in particular.     

Personality and Reaction Time after Sleep Deprivation

The relationship between reaction time and both state and trait personality variables was investigated in 37 participants after 30 h of sleep deprivation. Regression analyses suggested that endorsement of greater Novelty Seeking, anger/hostility, and depression/dejection, and less confusion, was associated with greater reaction time declines on one Multi-Attribute Task Battery index after sleep deprivation. Further, greater Novelty Seeking and depression/dejection, and less vigor/activity, was associated with greater reaction time declines after sleep deprivation on another Multi-Attribute Task Battery index. Additional correlational analyses indicated that better reaction times were associated with greater Novelty Seeking and lower anger/hostility prior to sleep deprivation, and less confusion/bewilderment following sleep deprivation. Findings suggest that both state and trait personality variables are associated with reaction time performance following sleep deprivation.